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Sequent calculus

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1603: 13373: 120:), and then the quantifiers are reintroduced. This very much parallels the way in which mathematical proofs are carried out in practice by mathematicians. Predicate calculus proofs are generally much easier to discover with this approach, and are often shorter. Natural deduction systems are more suited to practical theorem-proving. Sequent calculus systems are more suited to theoretical analysis. 11154: 8616: 10108: 12838:, p. 336, wrote in 1967 that "it was a major logical discovery by Gentzen 1934–5 that, when there is any (purely logical) proof of a proposition, there is a direct proof. The implications of this discovery are in theoretical logical investigations, rather than in building collections of proved formulas." 10985: 3247:): Every formula that can be proven in these has a reduction tree. This can be shown as follows: Every proof in propositional calculus uses only axioms and the inference rules. Each use of an axiom scheme yields a true logical formula, and can thus be proven in sequent calculus; examples for these are 11172:
These derivations also emphasize the strictly formal structure of the sequent calculus. For example, the logical rules as defined above always act on a formula immediately adjacent to the turnstile, such that the permutation rules are necessary. Note, however, that this is in part an artifact of the
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It is easy to see that the steps in the tree preserve the semantic truth value of the formulas implied by them, with conjunction understood between the tree's different branches whenever there is a split. It is also obvious that an axiom is provable if and only if it is true for every assignment of
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Weakening (W) allows the addition of arbitrary elements to a sequence. Intuitively, this is allowed in the antecedent because we can always restrict the scope of our proof (if all cars have wheels, then it's safe to say that all black cars have wheels); and in the succedent because we can always
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Starting with any formula in propositional logic, by a series of steps, the right side of the turnstile can be processed until it includes only atomic symbols. Then, the same is done for the left side. Since every logical operator appears in one of the rules above, and is removed by the rule, the
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In other words, natural deduction and sequent calculus systems are particular distinct kinds of Gentzen-style systems. Hilbert-style systems typically have a very small number of inference rules, relying more on sets of axioms. Gentzen-style systems typically have very few axioms, if any, relying
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in the classical natural deduction system NK is removed in the classical sequent calculus system LK. He said that the sequent calculus LJ gave more symmetry than natural deduction NJ in the case of intuitionistic logic, as also in the case of classical logic (LK versus NK). Then he said that in
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Note that, contrary to the rules for proceeding along the reduction tree presented above, the following rules are for moving in the opposite directions, from axioms to theorems. Thus they are exact mirror-images of the rules above, except that here symmetry is not implicitly assumed, and rules
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The items to the left of the turnstile are understood to be connected by conjunction, and those to the right by disjunction. Therefore, when both consist only of atomic symbols, the sequent is accepted axiomatically (and always true) if and only if at least one of the symbols on the right also
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At first sight, this extension of the judgment form may appear to be a strange complication—it is not motivated by an obvious shortcoming of natural deduction, and it is initially confusing that the comma seems to mean entirely different things on the two sides of the turnstile. However, in a
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Following are the rules by which one proceeds along the tree. Whenever one sequent is split into two, the tree vertex has two child vertices, and the tree is branched. Additionally, one may freely change the order of the arguments in each side; Γ and Δ stand for possible additional
2896: 10537: 12709:, p. 191. "Hiermit haben wir einige Gesichtspunkte zur BegrĂŒndung der Aufstellung der folgenden KalkĂŒle angegeben. Im wesentlichen ist ihre Form jedoch durch die RĂŒcksicht auf den nachher zu beweisenden 'Hauptsatz' bestimmt und kann daher vorlĂ€ufig nicht nĂ€her begrĂŒndet werden." 1101:
will also be true. Thus the empty sequent, having both cedents empty, is false. One way to express this is that a comma to the left of the turnstile should be thought of as an "and", and a comma to the right of the turnstile should be thought of as an (inclusive) "or". The sequents
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Gentzen asserted a sharp distinction between his single-output natural deduction systems (NK and NJ) and his multiple-output sequent calculus systems (LK and LJ). He wrote that the intuitionistic natural deduction system NJ was somewhat ugly. He said that the special role of the
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of formulas in the interpretation of the sequent, rather than sequences, eliminating the need for an explicit permutation rule. This corresponds to shifting commutativity of assumptions and derivations outside the sequent calculus, whereas LK embeds it within the system itself.
10829: 10683: 4168: 2592: 6268: 6129: 2697: 1548: 4792: 4685: 1563:, which manifests itself as logical negation on the semantic level, translates directly into a left–right symmetry of sequents—and indeed, the inference rules in sequent calculus for dealing with conjunction (∧) are mirror images of those dealing with disjunction (∹). 2990: 8473: 11560: 9927: 9788: 1412: 5010: 1558:
In these formulations, the only difference between formulae on either side of the turnstile is that one side is negated. Thus, swapping left for right in a sequent corresponds to negating all of the constituent formulae. This means that a symmetry such as
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Gentzen-style systems have significant practical and theoretical advantages compared to Hilbert-style systems. For example, both natural deduction and sequent calculus systems facilitate the elimination and introduction of universal and existential
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Instead of viewing the rules as descriptions for legal derivations in predicate logic, one may also consider them as instructions for the construction of a proof for a given statement. In this case the rules can be read bottom-up; for example,
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Next is the proof of a simple fact involving quantifiers. Note that the converse is not true, and its falsity can be seen when attempting to derive it bottom-up, because an existing free variable cannot be used in substitution in the rules
7058:. However, there are only finitely many possibilities to be checked since the antecedent by assumption is finite. This also illustrates how proof theory can be viewed as operating on proofs in a combinatorial fashion: given proofs for both 5800: 5719: 1280: 3267:(standing for Logistische KalkĂŒl) as introduced by Gentzen in 1934. A (formal) proof in this calculus is a sequence of sequents, where each of the sequents is derivable from sequents appearing earlier in the sequence by using one of the 9642: 1713: 286:). The theorems are those formulae that appear as the concluding judgment in a valid proof. A Hilbert-style system needs no distinction between formulae and judgments; we make one here solely for comparison with the cases that follow. 12680:
nahm der Satz vom ausgeschlossenen Dritten eine Sonderstellung unter den Schlußweisen ein , indem er sich der EinfĂŒhrungs- und Beseitigungssystematik nicht einfĂŒgte. Bei dem im folgenden anzugebenden logistischen klassichen KalkĂŒl
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makes the following comment on the translation into English: "Gentzen says 'Sequenz', which we translate as 'sequent', because we have already used 'sequence' for any succession of objects, where the German is 'Folge'."
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Many logicians feel that this symmetric presentation offers a deeper insight in the structure of the logic than other styles of proof system, where the classical duality of negation is not as apparent in the rules.
6398:. In contrast, the structural rules operate on the structure of the sequents, ignoring the exact shape of the formulae. The two exceptions to this general scheme are the axiom of identity (I) and the rule of (Cut). 1995: 10428: 7202:
The second rule that is somewhat special is the axiom of identity (I). The intuitive reading of this is obvious: every formula proves itself. Like the cut rule, the axiom of identity is somewhat redundant: the
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Thus, the sequents in the leaves of the trees include only atomic symbols, which are either provable by the axiom or not, according to whether one of the symbols on the right also appears on the left.
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Observe that all rules have mirror companions, except the ones for implication. This reflects the fact that the usual language of first-order logic does not include the "is not implied by" connective
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The price paid for the simple syntax of a Hilbert-style system is that complete formal proofs tend to get extremely long. Concrete arguments about proofs in such a system almost always appeal to the
12874:. Dort bestand er in Weglassung bzw. Hinzunahme des Satzes vom ausgeschlossenen Dritten, wĂ€hrend er hier durch die Sukzedensbedingung ausgedrĂŒckt wird." English translation: "The difference between 4584: 4056: 6800:
is true is not in general possible. If, however, the variable y is not mentioned elsewhere (i.e. it can still be chosen freely, without influencing the other formulae), then one may assume, that
2902: 8358: 7681: 11459: 377: 11652: 47:) instead of an unconditional tautology. Each conditional tautology is inferred from other conditional tautologies on earlier lines in a formal argument according to rules and procedures of 9834: 9695: 1301: 710: 11149:{\displaystyle \vdash \left(\left(A\rightarrow \left(B\lor C\right)\right)\rightarrow \left(\left(\left(B\rightarrow \lnot A\right)\land \lnot C\right)\rightarrow \lnot A\right)\right)} 2172: 2127: 11784: 11417: 3204: 12483:, pp. 440–516. This book is much more concerned with the theoretical, metamathematical implications of Gentzen-style sequent calculus than applications to practical logic proofs. 4919: 12898:. In the latter case, it consisted of the removal or addition respectively of the excluded middle rule, whereas in the former case, it is expressed through the succedent conditions." 9418: 3388: 2401: 13292: 7586: 7507: 10284: 10154: 9508: 8611:{\displaystyle {\left(\left(A\rightarrow \left(B\lor C\right)\right)\rightarrow \left(\left(\left(B\rightarrow \lnot A\right)\land \lnot C\right)\rightarrow \lnot A\right)\right)}} 2703: 11865: 7754: 7272: 3083: 2998: 7925: 2274: 11309: 9336: 9257: 11205:
Contraction (C) and Permutation (P) assure that neither the order (P) nor the multiplicity of occurrences (C) of elements of the sequences matters. Thus, one could instead of
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The resulting system is called LJ. It is sound and complete with respect to intuitionistic logic and admits a similar cut-elimination proof. This can be used in proving
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There is some freedom of choice regarding the technical details of how sequents and structural rules are formalized without changing what sequents the system derives.
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One may also change whether rules with more than one premise share the same context for each of those premises or split their contexts between them: For example,
11419:. Any weakening that appears in a derivation can then be moved to the beginning of the proof. This may be a convenient change when constructing proofs bottom-up. 9568: 9473: 9062: 8906: 8661: 7866: 7319: 1632: 7127:
When looking for some proof, most of the rules offer more or less direct recipes of how to do this. The rule of cut is different: it states that, when a formula
3943: 3920: 3897: 3874: 3851: 3828: 12267: 11254: 10980:{\displaystyle \left(A\rightarrow \left(B\lor C\right)\right)\vdash \left(\left(\left(B\rightarrow \lnot A\right)\land \lnot C\right)\rightarrow \lnot A\right)} 7185: 7165: 7145: 7096: 7076: 6996: 6956: 6835: 6798: 6674: 6594: 6477: 6356: 3803: 3766: 3746: 3726: 3706: 3686: 3666: 3646: 3626: 3540: 3520: 3498: 3354: 3334: 1013: 993: 973: 655: 528: 427: 268: 245: 11828:. To this end, one has to restrict to sequents with at most one formula on the right-hand side, and modify the rules to maintain this invariant. For example, 995:
are nonnegative integers, that is, the left-hand-side or the right-hand-side (or neither or both) may be empty. As in natural deduction, theorems are those
180:. Gentzen further demonstrated the power and flexibility of this technique a few years later, applying a cut-elimination argument to give a (transfinite) 59:, in which every line was an unconditional tautology. More subtle distinctions may exist; for example, propositions may implicitly depend upon non-logical 7234:
that would be the De Morgan dual of implication. Adding such a connective with its natural rules would make the calculus completely left–right symmetric.
12519:, pp. 184–244, compares natural deduction systems, denoted LA, and Gentzen systems, denoted LC. Curry's emphasis is more theoretical than practical. 12275: 11216:
The extra effort of using sequences, however, is justified since part or all of the structural rules may be omitted. Doing so, one obtains the so-called
1846: 4908:{\displaystyle {\cfrac {\Gamma \vdash A,\Delta \qquad \Sigma ,B\vdash \Pi }{\Gamma ,\Sigma ,A\rightarrow B\vdash \Delta ,\Pi }}\quad ({\rightarrow }L)} 12162: 8084: 2366:, as depicted on the right. The root of the tree is the formula we wish to prove; the leaves consist of atomic formulas only. The tree is known as a 1581:
addition to these reasons, the sequent calculus with multiple succedent formulas is intended particularly for his principal theorem ("Hauptsatz").
2891:{\displaystyle L\rightarrow {\text{rule: }}{\cfrac {\Gamma ,A\rightarrow B\vdash \Delta }{\Gamma \vdash \Delta ,A\qquad \Gamma ,B\vdash \Delta }}} 6401:
Although stated in a formal way, the above rules allow for a very intuitive reading in terms of classical logic. Consider, for example, the rule
116:. In a typical argument, quantifiers are eliminated, then propositional calculus is applied to unquantified expressions (which typically contain 10532:{\displaystyle \left(\left(B\rightarrow \lnot A\right)\land \lnot C\right),\left(A\rightarrow \left(B\lor C\right)\right)\vdash \lnot A,\lnot A} 12094:. When multi-formula consequents are interpreted as disjunctions, all of the other inference rules of LK are derivable in LJ, while the rules 1926: 13299: 721: 10824:{\displaystyle \left(A\rightarrow \left(B\lor C\right)\right),\left(\left(B\rightarrow \lnot A\right)\land \lnot C\right)\vdash \lnot A} 10678:{\displaystyle \left(\left(B\rightarrow \lnot A\right)\land \lnot C\right),\left(A\rightarrow \left(B\lor C\right)\right)\vdash \lnot A} 4163:{\displaystyle {\cfrac {\Gamma \vdash \Delta ,A\qquad A,\Sigma \vdash \Pi }{\Gamma ,\Sigma \vdash \Delta ,\Pi }}\quad ({\mathit {Cut}})} 1920:
Again the right hand side includes an implication, whose premise can further be assumed so that only its conclusion needs to be proven:
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This process can always be continued until there are only atomic formulas in each side. The process can be graphically described by a
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can be "cut out" and the respective derivations are joined. When constructing a proof bottom-up, this creates the problem of guessing
2587:{\displaystyle R\land {\text{rule: }}{\cfrac {\Gamma \vdash \Delta ,A\land B}{\Gamma \vdash \Delta ,A\qquad \Gamma \vdash \Delta ,B}}} 11186:
For certain formulations (i.e. variants) of the sequent calculus, a proof in such a calculus is isomorphic to an upside-down, closed
6263:{\displaystyle {\cfrac {\Gamma \vdash \Delta _{1},A,B,\Delta _{2}}{\Gamma \vdash \Delta _{1},B,A,\Delta _{2}}}\quad ({\mathit {PR}})} 6124:{\displaystyle {\cfrac {\Gamma _{1},A,B,\Gamma _{2}\vdash \Delta }{\Gamma _{1},B,A,\Gamma _{2}\vdash \Delta }}\quad ({\mathit {PL}})} 3239:
Sequent calculus is related to other axiomatizations of classical propositional calculus, such as Frege's propositional calculus or
2692:{\displaystyle L\lor {\text{rule: }}{\cfrac {\Gamma ,A\lor B\vdash \Delta }{\Gamma ,A\vdash \Delta \qquad \Gamma ,B\vdash \Delta }}} 796: 1543:{\displaystyle \vdash \neg (A_{1}\land A_{2}\land \cdots \land A_{n}\land \neg B_{1}\land \neg B_{2}\land \cdots \land \neg B_{k})} 1108: 580:
s and the turnstile are not written down explicitly; instead a two-dimensional notation from which they can be inferred is used.)
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Contraction and weakening make this version of the rule interderivable with the version above, although in their absence, as in
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allow for alternative conclusions (if all cars have wheels, then it's safe to say that all cars have either wheels or wings).
13224: 13202: 13180: 13131: 13109: 13087: 12961: 192:, and the general concepts relating to them, have been widely applied in the fields of proof theory, mathematical logic, and 7195:: it states that all uses of the cut rule can be eliminated from a proof, implying that any provable sequent can be given a 4002: 2985:{\displaystyle R\rightarrow {\text{rule: }}\quad {\cfrac {\Gamma \vdash \Delta ,A\rightarrow B}{\Gamma ,A\vdash \Delta ,B}}} 185: 13342: 12564:
Here, "whenever" is used as an informal abbreviation "for every assignment of values to the free variables in the judgment"
11972: 8468:{\displaystyle \exists y\left(\forall x\left(p(x,y)\right)\right)\vdash \forall x\left(\exists y\left(p(x,y)\right)\right)} 11555:{\displaystyle {\cfrac {\Gamma ,A\vdash \Delta \qquad \Sigma ,B\vdash \Pi }{\Gamma ,\Sigma ,A\lor B\vdash \Delta ,\Pi }}.} 12531:, pp. 25–150, is an introductory presentation of practical natural deduction of this kind. This became the basis of 12471:, pp. 189–244, calls Gentzen systems LC systems. Curry's emphasis is more on theory than on practical logic proofs. 7639: 13402: 3546: 317: 12507:, pp. 101–127, gives a brief theoretical presentation of Gentzen systems. He uses the tableau proof layout style. 9922:{\displaystyle \left(B\lor C\right),\left(\left(B\rightarrow \lnot A\right)\land \lnot C\right),\lnot C\vdash \lnot A} 9783:{\displaystyle \left(B\lor C\right),\lnot C,\left(\left(B\rightarrow \lnot A\right)\land \lnot C\right)\vdash \lnot A} 13153: 13061: 12939: 11611: 2082:
on the first argument on the left. Thus we may split the sequent to two, where we now have to prove each separately:
1407:{\displaystyle \vdash \neg A_{1}\lor \neg A_{2}\lor \cdots \lor \neg A_{n}\lor B_{1}\lor B_{2}\lor \cdots \lor B_{k}} 12547:
is an elementary introduction to practical natural deduction based on the convenient abbreviated proof layout style
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are equivalent in the strong sense that a proof of either sequent may be extended to a proof of the other sequent.
5005:{\displaystyle {\cfrac {\Gamma ,A\vdash B,\Delta }{\Gamma \vdash A\rightarrow B,\Delta }}\quad ({\rightarrow }R)} 663: 7147:
can be concluded and this formula may also serve as a premise for concluding other statements, then the formula
2484:{\displaystyle L\land {\text{rule: }}\quad {\cfrac {\Gamma ,A\land B\vdash \Delta }{\Gamma ,A,B\vdash \Delta }}} 2133: 2088: 11740: 11384: 3171: 181: 13267: 10363:{\displaystyle \left(\left(B\rightarrow \lnot A\right)\land \lnot C\right),\left(B\lor C\right)\vdash \lnot A} 10233:{\displaystyle \left(B\lor C\right),\left(\left(B\rightarrow \lnot A\right)\land \lnot C\right)\vdash \lnot A} 2786:{\displaystyle R\lor {\text{rule: }}\quad {\cfrac {\Gamma \vdash \Delta ,A\lor B}{\Gamma \vdash \Delta ,A,B}}} 13260: 11961:{\displaystyle {\cfrac {\Gamma ,A\vdash C\qquad \Gamma ,B\vdash C}{\Gamma ,A\lor B\vdash C}}\quad ({\lor }L)} 9382: 8618:. It is straightforward to find the derivation, which exemplifies the usefulness of LK in automated proving. 3945:: These six stand for the two versions of each of three structural rules; one for use on the left ('L') of a 3361: 3157:{\displaystyle R\lnot {\text{rule: }}\quad {\cfrac {\Gamma \vdash \Delta ,\lnot A}{\Gamma ,A\vdash \Delta }}} 3072:{\displaystyle L\lnot {\text{rule: }}\quad {\cfrac {\Gamma ,\lnot A\vdash \Delta }{\Gamma \vdash \Delta ,A}}} 293:. This leads to the idea of including the deduction theorem as a formal rule in the system, which happens in 212: 11800:
Alternatively, one may restrict or forbid the use of some of the structural rules. This yields a variety of
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This is written in the following form, where the proposition that needs to be proven is to the right of the
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Gentzen style. Every line is a conditional tautology (or theorem) with zero or more conditions on the left.
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ones. Each of the logical rules introduces a new logical formula either on the left or on the right of the
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on 2 November 2015, in his Keynote: "Propositions as Types". Minute 14:36 /55:28 of Code Mesh video clip
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sharing a certain style of inference and certain formal properties. The first sequent calculi systems,
13285: 13013: 12975: 11282: 9303: 9224: 5619:{\displaystyle {\cfrac {\Gamma \vdash A,\Delta }{\Gamma \vdash \exists xA,\Delta }}\quad ({\exists }R)} 5511:{\displaystyle {\cfrac {\Gamma ,A\vdash \Delta }{\Gamma ,\exists xA\vdash \Delta }}\quad ({\exists }L)} 5401:{\displaystyle {\cfrac {\Gamma \vdash A,\Delta }{\Gamma \vdash \forall xA,\Delta }}\quad ({\forall }R)} 5293:{\displaystyle {\cfrac {\Gamma ,A\vdash \Delta }{\Gamma ,\forall xA\vdash \Delta }}\quad ({\forall }L)} 4473:{\displaystyle {\cfrac {\Gamma ,B\vdash \Delta }{\Gamma ,A\land B\vdash \Delta }}\quad ({\land }L_{2})} 4275:{\displaystyle {\cfrac {\Gamma ,A\vdash \Delta }{\Gamma ,A\land B\vdash \Delta }}\quad ({\land }L_{1})} 3410:
are finite (possibly empty) sequences of formulae (in fact, the order of formulae does not matter; see
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are equivalent in the strong sense that a proof of either one may be extended to a proof of the other.
13250: 12697:, p. 191. "Die damit erreichte Symmetrie erweist sich als fĂŒr die klassische Logik angemessener." 8809: 8736: 7394: 7217: 12980: 11317: 10999: 10843: 10396: 9536: 8307:{\displaystyle \exists y\left(\forall x\left(p(x,y)\right)\right)\vdash \exists y\left(p(x,y)\right)} 6404: 4571:{\displaystyle {\cfrac {\Gamma \vdash B,\Delta }{\Gamma \vdash A\lor B,\Delta }}\quad ({\lor }R_{2})} 4373:{\displaystyle {\cfrac {\Gamma \vdash A,\Delta }{\Gamma \vdash A\lor B,\Delta }}\quad ({\lor }R_{1})} 11374:. In this case, the rules for permuting and (when using sets) contracting formulae are unnecessary. 2180: 13397: 12128: 12066: 9941: 9656: 6707: 6310: 6279: 5983:{\displaystyle {\cfrac {\Gamma \vdash A,A,\Delta }{\Gamma \vdash A,\Delta }}\quad ({\mathit {CR}})} 5890:{\displaystyle {\cfrac {\Gamma ,A,A\vdash \Delta }{\Gamma ,A\vdash \Delta }}\quad ({\mathit {CL}})} 3356:
denote formulae of first-order predicate logic (one may also restrict this to propositional logic),
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so that unquantified logical expressions can be manipulated according to the much simpler rules of
7600: 7435: 6738: 5183:{\displaystyle {\cfrac {\Gamma ,A\vdash \Delta }{\Gamma \vdash \lnot A,\Delta }}\quad ({\lnot }R)} 5095:{\displaystyle {\cfrac {\Gamma \vdash A,\Delta }{\Gamma ,\lnot A\vdash \Delta }}\quad ({\lnot }L)} 13337: 13172: 12390: 11813: 9137: 8981: 8326: 8181: 8052: 7939: 7805: 7776: 7188: 6844: 169: 12811: 11831: 11425: 6528: 12097: 11981: 11824:
Surprisingly, some small changes in the rules of LK suffice to turn it into a proof system for
11598: 9350: 9070: 8914: 8704: 8669: 7362: 7327: 7276: 7018:, respectively. Note that, given some antecedent, it is not clear how this is to be split into 5795:{\displaystyle {\cfrac {\Gamma \vdash \Delta }{\Gamma \vdash A,\Delta }}\quad ({\mathit {WR}})} 5714:{\displaystyle {\cfrac {\Gamma \vdash \Delta }{\Gamma ,A\vdash \Delta }}\quad ({\mathit {WL}})} 1577: 1275:{\displaystyle \vdash (A_{1}\land \cdots \land A_{n})\rightarrow (B_{1}\lor \cdots \lor B_{k})} 113: 109: 97:
Sequent calculus. Every (conditional) line has zero or more asserted propositions on the right.
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The usual term for the horizontal line used in Gentzen-style layouts for natural deduction is
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presentation, in the original style of Gentzen. A common simplification involves the use of
9637:{\displaystyle \left(B\lor C\right),\lnot C,\left(B\rightarrow \lnot A\right)\vdash \lnot A} 1708:{\displaystyle ((p\rightarrow r)\lor (q\rightarrow r))\rightarrow ((p\land q)\rightarrow r)} 13322: 11978:
In fact, the only rules in LK that need to be restricted to single-formula consequents are
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The standard semantics of a judgment in natural deduction is that it asserts that whenever
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the semantics of the sequent can also (by propositional tautology) be expressed either as
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An Introduction to Proof Theory — Normalization, Cut-Elimination, and Consistency Proofs
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Now, instead of proving this from the axioms, it is enough to assume the premise of the
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Or if, as described above, weakening is to be an admissible rule, then with the axiom:
11239: 7170: 7150: 7130: 7081: 7061: 6981: 6941: 6803: 6766: 6659: 6579: 6462: 6376: 6341: 3983: 3771: 3751: 3731: 3711: 3691: 3671: 3651: 3631: 3594: 3525: 3505: 3483: 3339: 3319: 3303: 1719: 998: 978: 958: 878: 640: 513: 460: 412: 279: 253: 230: 133: 20: 12909:
Proceedings Of The Third Annual Symposium On Logic In Computer Science, July 5-8, 1988
12777: 1602: 13220: 13198: 13176: 13149: 13127: 13105: 13083: 13057: 13037: 13001: 12957: 12935: 12929: 12593: 12574: 12385: 11210: 3268: 306: 294: 290: 153: 149: 91: 68: 36: 13056:. Cambridge University Press (Cambridge Tracts in Theoretical Computer Science, 7). 210:
One way to classify different styles of deduction systems is to look at the form of
13190: 13045: 13025: 12989: 12366:{\displaystyle {\cfrac {\Gamma \vdash A\lor C}{\Gamma \vdash (\forall xA)\lor C}}.} 11809: 11370:
First of all, as mentioned above, the sequents can be viewed to consist of sets or
1910:{\displaystyle (p\rightarrow r)\lor (q\rightarrow r)\vdash (p\land q)\rightarrow r} 13050: 12612:
For explanations of the disjunctive semantics for the right side of sequents, see
12582: 790:
Finally, sequent calculus generalizes the form of a natural deduction judgment to
13327: 13272: 13009: 12971: 11378: 11344: 6837:
holds for any value of y. The other rules should then be pretty straightforward.
1555:(it cannot be the case that all of the As are true and all of the Bs are false). 1290: 157: 44: 12239:{\displaystyle {\cfrac {\Gamma ,A\vdash B\lor C}{\Gamma \vdash (A\to B)\lor C}}} 11737:, negation can be subsumed as a special case of implication, via the definition 1840:
and then try to prove its conclusion. Hence one moves to the following sequent:
13212: 12925: 12812:
An Introduction to the Theory and Applications of Propositional Sequent Calculi
11311: 8162:{\displaystyle \forall x\left(p(x,y)\right)\vdash \exists y\left(p(x,y)\right)} 7208: 3244: 221: 205: 82: 75: 2318:
The second sequent is done; the first sequent can be further simplified into:
13386: 13071: 12949: 12760: 12748: 1589:
The word "sequent" is taken from the word "Sequenz" in Gentzen's 1934 paper.
1570: 483:", with a single formula on the right-hand side, (though permutations of the 137: 117: 94:. Every (conditional) line has exactly one asserted proposition on the right. 52: 13332: 13317: 13164: 13075: 12400: 11566: 3252: 877:
a syntactic object called a sequent. The formulas on left-hand side of the
129: 56: 32: 9440: 9030: 8874: 8870: 8866: 8862: 8858: 8628: 8624: 8620: 7833: 7286: 3212:
process terminates when no logical operators remain: The formula has been
13352: 13141: 12578: 3476:(at least one of the formulas must hold for any assignment of variables), 283: 274:
of first-order logic (or whatever logic the deduction system applies to,
177: 148:, were introduced in 1934/1935 by Gerhard Gentzen as a tool for studying 13372: 13244: 12814:(2021, chapter "Gentzen's Sequent Calculus LK"). Accessed 3 August 2022. 12459:, pp. 453, gives a very brief proof of the cut-elimination theorem. 1990:{\displaystyle (p\rightarrow r)\lor (q\rightarrow r),(p\land q)\vdash r} 13029: 12993: 12756: 2000:
Since the arguments in the left-hand side are assumed to be related by
173: 3965:, and the other on its right ('R'). The rules are abbreviated 'W' for 1606:
A rooted tree describing a proof finding procedure by sequent calculus
11257: 11229: 3224: 48: 13277: 12928:(1998). "An introduction to proof theory". In Samuel R. Buss (ed.). 12548: 12532: 11371: 11206: 11174: 772:{\displaystyle \vdash (A_{1}\land \cdots \land A_{n})\rightarrow B} 28: 2078:
This is equivalent to proving the conclusion in both cases of the
1041:
The standard semantics of a sequent is an assertion that whenever
12573: 2068:{\displaystyle (p\rightarrow r)\lor (q\rightarrow r),p,q\vdash r} 64: 40: 6704:
For an intuition about the quantifier rules, consider the rule
1615:
Sequent calculus can be seen as a tool for proving formulas in
11859:
is reformulated as follows (where C is an arbitrary formula):
11381:
if the axiom (I) is changed to derive any sequent of the form
6358:
must not occur free anywhere in the respective lower sequents.
3628:
denotes the formula that is obtained by substituting the term
867:{\displaystyle A_{1},\ldots ,A_{n}\vdash B_{1},\ldots ,B_{k},} 164:
versions, respectively). Gentzen's so-called "Main Theorem" (
11819: 6459:
can be concluded from some sequence of formulae that contain
1419:(at least one of the As is false, or one of the Bs is true) 1176:{\displaystyle A_{1},\ldots ,A_{n}\vdash B_{1},\ldots ,B_{k}} 60: 13044: 3251:. The only inference rule in the systems mentioned above is 7191:
is thus crucial to the applications of sequent calculus in
12778:"Gentzen's original consistency proof and the Bar Theorem" 3263:
This section introduces the rules of the sequent calculus
1571:
Distinction between natural deduction and sequent calculus
510:'s are often immaterial). The theorems are those formulae 11198:
The structural rules deserve some additional discussion.
8033:{\displaystyle \forall x\left(p(x,y)\right)\vdash p(x,y)} 6252: 6113: 5972: 5879: 5784: 5703: 4152: 4149: 12452: 12450: 11707:{\displaystyle {\cfrac {}{\Gamma ,\bot \vdash \Delta }}} 3223:
truth values to the atomic symbols. Thus this system is
459:(possibly empty) of formulae on the left-hand side of a 85:. Every line is an unconditional tautology (or theorem). 12890:
of an extremely, totally different kind to the case of
12437: 12435: 12323: 12282: 12199: 12169: 11912: 11872: 11679: 11670: 11627: 11618: 11506: 11466: 6192: 6142: 6053: 6003: 5938: 5908: 5845: 5815: 5750: 5732: 5669: 5651: 5570: 5529: 5462: 5421: 5352: 5311: 5244: 5203: 5137: 5113: 5049: 5025: 4956: 4926: 4847: 4807: 4738: 4698: 4631: 4591: 4515: 4491: 4417: 4393: 4317: 4293: 4219: 4195: 4109: 4069: 4019: 4009: 3234: 3129: 3102: 3044: 3017: 2951: 2921: 2847: 2817: 2752: 2722: 2648: 2618: 2543: 2513: 2450: 2420: 188:. Since this early work, sequent calculi, also called 13082:(Second ed.). Berlin, New York: Springer-Verlag. 12326: 12285: 12202: 12172: 11915: 11875: 11682: 11673: 11630: 11621: 11509: 11469: 6367:
The above rules can be divided into two major groups:
6195: 6145: 6056: 6006: 5941: 5911: 5848: 5818: 5753: 5735: 5672: 5654: 5573: 5532: 5465: 5424: 5355: 5314: 5247: 5206: 5140: 5116: 5052: 5028: 4959: 4929: 4850: 4810: 4741: 4701: 4634: 4594: 4518: 4494: 4420: 4396: 4320: 4296: 4222: 4198: 4112: 4072: 4051:{\displaystyle {\cfrac {\qquad }{A\vdash A}}\quad (I)} 4022: 4012: 3132: 3105: 3047: 3020: 2954: 2924: 2850: 2820: 2755: 2725: 2651: 2621: 2546: 2516: 2453: 2423: 12447: 12278: 12255: 12165: 12131: 12100: 12069: 12044: 12015: 11984: 11868: 11834: 11743: 11723: 11666: 11614: 11583: 11462: 11428: 11387: 11320: 11285: 11266: 11242: 11034: 11002: 10878: 10846: 10732: 10700: 10586: 10554: 10431: 10399: 10287: 10255: 10157: 10125: 9983: 9944: 9837: 9805: 9698: 9659: 9571: 9539: 9484: 9455: 9385: 9353: 9306: 9274: 9227: 9195: 9140: 9108: 9073: 9044: 8984: 8952: 8917: 8888: 8812: 8780: 8739: 8707: 8672: 8643: 8497: 8361: 8329: 8216: 8184: 8087: 8055: 7974: 7942: 7877: 7848: 7808: 7779: 7730: 7698: 7642: 7603: 7556: 7524: 7477: 7438: 7397: 7365: 7330: 7301: 7248: 7220: 7173: 7153: 7133: 7104: 7084: 7064: 7044: 7024: 7004: 6984: 6964: 6944: 6924: 6904: 6878: 6847: 6806: 6769: 6741: 6710: 6701:
holds. All the rules can be interpreted in this way.
6682: 6662: 6642: 6622: 6602: 6582: 6562: 6531: 6505: 6485: 6465: 6445: 6407: 6384: 6344: 6313: 6282: 6138: 5999: 5904: 5811: 5728: 5647: 5525: 5417: 5307: 5199: 5109: 5021: 4922: 4803: 4694: 4587: 4487: 4389: 4289: 4191: 4065: 4005: 3951: 3928: 3905: 3882: 3859: 3836: 3813: 3774: 3754: 3734: 3714: 3694: 3674: 3654: 3634: 3597: 3575: 3555: 3528: 3508: 3486: 3458: 3427: 3396: 3364: 3342: 3322: 3288: 3174: 3086: 3001: 2905: 2802: 2706: 2603: 2498: 2404: 2327: 2283: 2241: 2209: 2183: 2136: 2091: 2013: 1929: 1849: 1750: 1727: 1635: 1584: 1431: 1304: 1195: 1111: 1080: 1050: 1021: 1001: 981: 961: 934: 907: 885:, and the formulas on right-hand side are called the 799: 724: 666: 643: 616: 589: 559: 536: 516: 489: 469: 435: 415: 388: 320: 256: 233: 12432: 11236:
with respect to first-order logic, i.e. a statement
74:
Sequent calculus is one of several extant styles of
12907:M. Tiomkin, "Proving unprovability", pp.22--26. In 3549:within a formula if it is not bound by quantifiers 13049: 12365: 12261: 12238: 12148: 12117: 12086: 12055: 12030: 12001: 11960: 11851: 11778: 11729: 11706: 11646: 11589: 11554: 11445: 11411: 11332: 11303: 11272: 11248: 11148: 11017: 10979: 10861: 10823: 10715: 10677: 10569: 10531: 10414: 10362: 10270: 10232: 10140: 10102: 9966: 9921: 9820: 9782: 9681: 9636: 9554: 9502: 9467: 9412: 9368: 9330: 9289: 9251: 9210: 9158: 9123: 9085: 9056: 9002: 8967: 8929: 8900: 8830: 8795: 8757: 8722: 8684: 8655: 8610: 8467: 8344: 8306: 8199: 8161: 8070: 8032: 7957: 7919: 7860: 7823: 7794: 7748: 7713: 7676:{\displaystyle \vdash A\lor \lnot A,A\lor \lnot A} 7675: 7625: 7580: 7539: 7501: 7460: 7415: 7380: 7342: 7313: 7266: 7226: 7179: 7159: 7139: 7116: 7090: 7070: 7050: 7030: 7010: 6990: 6970: 6950: 6930: 6910: 6890: 6864: 6829: 6792: 6755: 6727: 6693: 6668: 6648: 6628: 6608: 6588: 6568: 6548: 6517: 6491: 6471: 6451: 6431: 6390: 6350: 6330: 6299: 6262: 6123: 5982: 5889: 5794: 5713: 5618: 5510: 5400: 5292: 5182: 5094: 5004: 4907: 4786: 4679: 4570: 4472: 4372: 4274: 4162: 4050: 3957: 3937: 3914: 3891: 3868: 3845: 3822: 3797: 3760: 3740: 3720: 3700: 3680: 3660: 3640: 3620: 3581: 3561: 3534: 3514: 3492: 3464: 3433: 3402: 3382: 3348: 3328: 3294: 3198: 3156: 3071: 2984: 2890: 2785: 2691: 2586: 2483: 2351: 2307: 2268: 2224: 2195: 2166: 2121: 2067: 1989: 1909: 1825: 1733: 1707: 1542: 1406: 1274: 1175: 1093: 1063: 1030: 1007: 987: 967: 947: 920: 866: 771: 704: 649: 629: 602: 572: 545: 522: 502: 475: 447: 421: 401: 371: 262: 239: 199: 13162: 12418: 12416: 11359:The above rules can be modified in various ways: 372:{\displaystyle A_{1},A_{2},\ldots ,A_{n}\vdash B} 13384: 13014:"Untersuchungen ĂŒber das logische Schließen. II" 12850:, p. 194, wrote: "Der Unterschied zwischen 11362: 11181: 12976:"Untersuchungen ĂŒber das logische Schließen. I" 11647:{\displaystyle {\cfrac {}{\bot \vdash \quad }}} 11347:. This result is also referred to as Gentzen's 311:In natural deduction, judgments have the shape 78:for expressing line-by-line logical arguments. 13070: 12785:Gentzen's Centenary: The Quest for Consistency 12625: 12581:; Stringer-Calvert, David W. J. (2001-11-01). 12413: 12376:These rules are not intuitionistically valid. 11223: 8491:For something more interesting we shall prove 2177:In the case of the first judgment, we rewrite 13293: 11228:This system of rules can be shown to be both 7187:(since it does not appear at all below). The 63:. In that case, sequents signify conditional 13273:Interactive tutorial of the Sequent Calculus 12731: 12729: 12727: 11804:systems. They are generally weaker than LK ( 11569:, these rules define different connectives. 6439:. It says that, whenever one can prove that 300: 182:proof of the consistency of Peano arithmetic 12269:does not occur free in the bottom sequent) 6362: 1597: 785: 705:{\displaystyle A_{1},\ldots ,A_{n}\vdash B} 455:. In other words, a judgment consists of a 13300: 13286: 12801:, Cambridge University Press, 2014, p. 32. 12736:Applied Logic, Univ. of Cornell: Lecture 9 12676:, p. 191. "In dem klassischen KalkĂŒl 12567: 11820:Intuitionistic sequent calculus: System LJ 11760: 11756: 7207:states that the rule can be restricted to 3648:for every free occurrence of the variable 2167:{\displaystyle q\rightarrow r,p,q\vdash r} 2122:{\displaystyle p\rightarrow r,p,q\vdash r} 13219:. Mineola, New York: Dover Publications. 13126:. Mineola, New York: Dover Publications. 12724: 11779:{\displaystyle (\neg A)\iff (A\to \bot )} 11412:{\displaystyle \Gamma ,A\vdash A,\Delta } 10393: 9533: 9189: 3472:, the sequence of formulas is considered 3441:, the sequence of formulas is considered 3199:{\displaystyle \Gamma ,A\vdash \Delta ,A} 2004:, this can be replaced by the following: 13189: 12823: 12629: 12504: 12038:(which can be seen as a special case of 11028: 10872: 10726: 10580: 10425: 10281: 10151: 9977: 9831: 9692: 9565: 9478: 9379: 9300: 9221: 9134: 9067: 8978: 8911: 8806: 8733: 8666: 8355: 8210: 8081: 7968: 7871: 7724: 7636: 7550: 7471: 7391: 7324: 3748:(i.e., no occurrence of any variable in 3255:, which is implemented by the cut rule. 3248: 1601: 13008: 12970: 12847: 12787:. New York: Springer. pp. 213–228. 12706: 12694: 12673: 12657: 12633: 12426: 12422: 11789: 9413:{\displaystyle B\lor C,\lnot C\vdash B} 7205:completeness of atomic initial sequents 3445:(all assumed to hold at the same time), 3383:{\displaystyle \Gamma ,\Delta ,\Sigma } 13385: 13211: 13140: 13118: 13096: 12835: 12741: 12718: 12685:wird diese Sonderstellung aufgehoben." 12621: 12617: 12552: 12544: 12528: 12492: 12480: 12456: 7581:{\displaystyle \vdash A,A\lor \lnot A} 7502:{\displaystyle \vdash A\lor \lnot A,A} 7237: 13307: 13281: 12948: 12613: 12516: 12468: 12441: 11343:In the sequent calculus, the rule of 9503:{\displaystyle \lnot A\vdash \lnot A} 3411: 3279:The following notation will be used: 71:rather than conditional tautologies. 16:Style of formal logical argumentation 13343:Propositional directed acyclic graph 13048:; Paul Taylor; Yves Lafont (1990) . 12956:. New York: Dover Publications Inc. 12924: 12882:logic is in the case of the calculi 12775: 12769: 12645: 11973:disjunction and existence properties 7749:{\displaystyle \vdash A\lor \lnot A} 7267:{\displaystyle \vdash A\lor \lnot A} 6636:alone one can either still conclude 6499:from the (stronger) assumption that 3235:Relation to standard axiomatizations 2232:and split the sequent again to get: 1038:is the conclusion of a valid proof. 13268:A Brief Diversion: Sequent Calculus 13245:Stanford Encyclopedia of Philosophy 12866:Ă€ußerlich ganz anderer Art als bei 11340:can be derived by the above rules. 11193: 7920:{\displaystyle p(x,y)\vdash p(x,y)} 3688:with the restriction that the term 3231:for classical propositional logic. 2269:{\displaystyle \lnot p,p,q\vdash r} 13: 12664:hat manche formale Unschönheiten." 12337: 12328: 12287: 12204: 12174: 12136: 12074: 12019: 11917: 11893: 11877: 11770: 11747: 11724: 11696: 11690: 11684: 11632: 11584: 11541: 11535: 11517: 11511: 11499: 11487: 11483: 11471: 11406: 11388: 11321: 11289: 11267: 11130: 11116: 11102: 10966: 10952: 10938: 10815: 10801: 10787: 10669: 10617: 10603: 10523: 10514: 10462: 10448: 10354: 10318: 10304: 10224: 10210: 10196: 10094: 10080: 10066: 10036: 10022: 9913: 9904: 9890: 9876: 9774: 9760: 9746: 9721: 9628: 9614: 9594: 9494: 9485: 9398: 9357: 8822: 8743: 8711: 8591: 8577: 8563: 8426: 8415: 8373: 8362: 8333: 8270: 8228: 8217: 8188: 8125: 8088: 8059: 7975: 7946: 7812: 7783: 7740: 7667: 7652: 7572: 7487: 7401: 7369: 7258: 7045: 7025: 7005: 6965: 6925: 6905: 6742: 6715: 6684: 6643: 6623: 6603: 6563: 6536: 6486: 6446: 6318: 6287: 6249: 6229: 6204: 6197: 6179: 6154: 6147: 6110: 6096: 6084: 6059: 6046: 6034: 6009: 5969: 5955: 5943: 5931: 5913: 5876: 5862: 5850: 5838: 5820: 5781: 5767: 5755: 5743: 5737: 5700: 5686: 5674: 5662: 5656: 5606: 5593: 5581: 5575: 5563: 5534: 5498: 5485: 5473: 5467: 5455: 5426: 5388: 5375: 5363: 5357: 5345: 5316: 5280: 5267: 5255: 5249: 5237: 5208: 5170: 5157: 5148: 5142: 5130: 5118: 5082: 5069: 5060: 5054: 5042: 5030: 4979: 4961: 4949: 4931: 4882: 4876: 4858: 4852: 4840: 4828: 4824: 4812: 4761: 4743: 4731: 4719: 4715: 4703: 4654: 4636: 4624: 4612: 4608: 4596: 4538: 4520: 4508: 4496: 4440: 4422: 4410: 4398: 4340: 4322: 4310: 4298: 4242: 4224: 4212: 4200: 4146: 4132: 4126: 4120: 4114: 4102: 4096: 4080: 4074: 3576: 3556: 3397: 3377: 3371: 3365: 3274: 3187: 3175: 3146: 3134: 3119: 3113: 3107: 3090: 3055: 3049: 3037: 3028: 3022: 3005: 2968: 2956: 2932: 2926: 2880: 2868: 2858: 2852: 2840: 2822: 2763: 2757: 2733: 2727: 2681: 2669: 2665: 2653: 2641: 2623: 2570: 2564: 2554: 2548: 2524: 2518: 2473: 2455: 2443: 2425: 2242: 2210: 1610: 1524: 1502: 1486: 1435: 1346: 1324: 1308: 136:, sequent calculus is a family of 14: 13414: 13234: 12954:Foundations of mathematical logic 12911:(1988), IEEE. ISBN 0-8186-0853-6. 11304:{\displaystyle (\Gamma \vDash A)} 9331:{\displaystyle B\lor C\vdash C,B} 9252:{\displaystyle B\lor C\vdash B,C} 7211:without any loss of provability. 657:will also be true. The judgments 13371: 13197:. New York: Dover Publications. 13163:Mancosu, Paolo; Galvan, Sergio; 12783:. In Kahle R, Rathjen M (eds.). 8831:{\displaystyle \vdash A,\lnot A} 8758:{\displaystyle \vdash \lnot A,A} 7416:{\displaystyle \vdash \lnot A,A} 7227:{\displaystyle \not \leftarrow } 7098:, one can construct a proof for 3258: 3241:Jan Ɓukasiewicz's axiomatization 1626:Consider the following formula: 224:, where a judgment has the form 13102:Introduction to metamathematics 12901: 12841: 12829: 12817: 12804: 12791: 12712: 12700: 12688: 12667: 12651: 12639: 12606: 12558: 12538: 11943: 11892: 11638: 11486: 11333:{\displaystyle \Gamma \vdash A} 11018:{\displaystyle (\rightarrow R)} 10862:{\displaystyle (\rightarrow R)} 10415:{\displaystyle (\rightarrow L)} 9555:{\displaystyle (\rightarrow L)} 6432:{\displaystyle ({\land }L_{1})} 6243: 6104: 5963: 5870: 5775: 5694: 5601: 5493: 5383: 5275: 5165: 5077: 4987: 4890: 4827: 4769: 4718: 4662: 4611: 4546: 4448: 4348: 4250: 4140: 4089: 4038: 4014: 3243:(itself a part of the standard 3098: 3013: 2917: 2867: 2718: 2668: 2563: 2416: 222:Hilbert-style deduction systems 200:Hilbert-style deduction systems 186:Gödel's incompleteness theorems 13241:Proof Theory (Sequent Calculi) 12522: 12510: 12498: 12486: 12474: 12462: 12346: 12334: 12310: 12296: 12222: 12216: 12210: 12143: 12132: 12112: 12105: 12101: 12081: 12070: 12046: 12025: 12016: 11996: 11989: 11985: 11955: 11944: 11846: 11835: 11773: 11767: 11761: 11757: 11753: 11744: 11440: 11429: 11377:The rule of weakening becomes 11298: 11286: 11127: 11099: 11078: 11051: 11012: 11006: 11003: 10963: 10935: 10887: 10856: 10850: 10847: 10784: 10741: 10710: 10701: 10639: 10600: 10564: 10555: 10484: 10445: 10409: 10403: 10400: 10301: 10265: 10256: 10193: 10135: 10126: 10063: 10019: 9961: 9945: 9873: 9815: 9806: 9743: 9676: 9660: 9611: 9549: 9543: 9540: 9462: 9456: 9363: 9354: 9284: 9275: 9205: 9196: 9118: 9109: 9051: 9045: 8962: 8953: 8895: 8889: 8790: 8781: 8717: 8708: 8650: 8644: 8588: 8560: 8539: 8512: 8452: 8440: 8399: 8387: 8339: 8330: 8296: 8284: 8254: 8242: 8194: 8185: 8151: 8139: 8114: 8102: 8065: 8056: 8027: 8015: 8001: 7989: 7952: 7943: 7914: 7902: 7893: 7881: 7855: 7849: 7818: 7809: 7789: 7780: 7708: 7699: 7620: 7604: 7534: 7525: 7455: 7439: 7375: 7366: 7308: 7302: 6859: 6848: 6824: 6810: 6787: 6773: 6763:holds just from the fact that 6722: 6711: 6543: 6532: 6426: 6408: 6325: 6314: 6294: 6283: 6257: 6244: 6118: 6105: 5977: 5964: 5884: 5871: 5789: 5776: 5708: 5695: 5613: 5602: 5557: 5543: 5505: 5494: 5449: 5435: 5395: 5384: 5339: 5325: 5287: 5276: 5231: 5217: 5177: 5166: 5089: 5078: 4999: 4992: 4988: 4970: 4902: 4895: 4891: 4867: 4781: 4770: 4674: 4663: 4565: 4547: 4467: 4449: 4367: 4349: 4269: 4251: 4157: 4141: 4045: 4039: 3792: 3778: 3708:must be free for the variable 3615: 3601: 2941: 2909: 2831: 2806: 2196:{\displaystyle p\rightarrow r} 2187: 2140: 2095: 2044: 2038: 2032: 2026: 2020: 2014: 1978: 1966: 1960: 1954: 1948: 1942: 1936: 1930: 1901: 1898: 1886: 1880: 1874: 1868: 1862: 1856: 1850: 1820: 1814: 1811: 1799: 1796: 1793: 1790: 1787: 1781: 1775: 1769: 1763: 1757: 1754: 1702: 1696: 1693: 1681: 1678: 1675: 1672: 1669: 1663: 1657: 1651: 1645: 1639: 1636: 1537: 1438: 1269: 1237: 1234: 1231: 1199: 763: 760: 728: 278:, propositional calculus or a 1: 12918: 12799:Elements of Logical Reasoning 12149:{\displaystyle ({\forall }R)} 12087:{\displaystyle ({\forall }R)} 11453:may be instead formulated as 11363:Minor structural alternatives 11182:Relation to analytic tableaux 9967:{\displaystyle (\land L_{2})} 9682:{\displaystyle (\land L_{1})} 9439: 9029: 8873: 8865: 8857: 8627: 6898:follows from the assumptions 6728:{\displaystyle ({\forall }R)} 6479:, then one can also conclude 6331:{\displaystyle ({\exists }L)} 6300:{\displaystyle ({\forall }R)} 2352:{\displaystyle p,q\vdash p,r} 2308:{\displaystyle r,p,q\vdash r} 2225:{\displaystyle \lnot p\lor r} 172:, a result with far-reaching 27:is a style of formal logical 13104:. Ishi Press International. 13080:Grundlagen der Mathematik II 12747:"Remember, the way that you 12738:. Last Retrieved: 2016-06-25 11572: 7626:{\displaystyle (\lor R_{1})} 7461:{\displaystyle (\lor R_{2})} 6938:, it suffices to prove that 6756:{\displaystyle \forall {x}A} 6735:. Of course concluding that 3545:a variable is said to occur 184:, in surprising response to 7: 13363:Method of analytic tableaux 13348:Sentential decision diagram 13256:Encyclopedia of Mathematics 13010:Gentzen, Gerhard Karl Erich 12972:Gentzen, Gerhard Karl Erich 12934:. Elsevier. pp. 1–78. 12858:Logik ist bei den KalkĂŒlen 12660:, p. 188. "Der KalkĂŒl 12379: 11354: 11224:Properties of the system LK 9159:{\displaystyle C\vdash B,C} 9003:{\displaystyle B\vdash B,C} 8345:{\displaystyle (\forall R)} 8200:{\displaystyle (\exists L)} 8071:{\displaystyle (\exists R)} 7958:{\displaystyle (\forall L)} 7824:{\displaystyle (\exists L)} 7795:{\displaystyle (\forall R)} 7242:Here is the derivation of " 6865:{\displaystyle ({\land }R)} 6276:Restrictions: In the rules 1621:method of analytic tableaux 893:; together they are called 123: 10: 13419: 12626:Hilbert & Bernays 1970 12063:, as described above) and 11852:{\displaystyle ({\lor }L)} 11793: 11446:{\displaystyle ({\lor }L)} 6549:{\displaystyle ({\neg }R)} 6525:holds. Likewise, the rule 3500:denotes an arbitrary term, 304: 203: 168:) about LK and LJ was the 13403:Automated theorem proving 13369: 13313: 13191:Smullyan, Raymond Merrill 13018:Mathematische Zeitschrift 12981:Mathematische Zeitschrift 12118:{\displaystyle ({\to }R)} 12002:{\displaystyle ({\to }R)} 10996: 10840: 10694: 10548: 10249: 10119: 9938: 9799: 9653: 9449: 9369:{\displaystyle (\lnot L)} 9347: 9268: 9102: 9086:{\displaystyle C\vdash C} 9038: 8946: 8930:{\displaystyle B\vdash B} 8882: 8774: 8723:{\displaystyle (\lnot R)} 8701: 8685:{\displaystyle A\vdash A} 8637: 8323: 8178: 8049: 7936: 7842: 7692: 7597: 7518: 7432: 7381:{\displaystyle (\lnot R)} 7359: 7343:{\displaystyle A\vdash A} 7295: 6872:says that, to prove that 3167: 301:Natural deduction systems 31:in which every line of a 12931:Handbook of proof theory 12406: 12031:{\displaystyle (\neg R)} 9211:{\displaystyle (\lor L)} 7117:{\displaystyle A\land B} 6891:{\displaystyle A\land B} 6694:{\displaystyle {\neg }A} 6518:{\displaystyle A\land B} 6363:An intuitive explanation 3582:{\displaystyle \exists } 3562:{\displaystyle \forall } 1598:Proving logical formulas 1585:Origin of word "sequent" 1031:{\displaystyle \vdash B} 786:Sequent calculus systems 546:{\displaystyle \vdash B} 176:consequences, including 13338:Binary decision diagram 13213:Suppes, Patrick Colonel 13173:Oxford University Press 12632:, pp. 104–105 and 12391:Nested sequent calculus 12056:{\displaystyle {\to }R} 11814:artificial intelligence 11273:{\displaystyle \Gamma } 11260:from a set of premises 7189:cut-elimination theorem 7051:{\displaystyle \Sigma } 7031:{\displaystyle \Gamma } 7011:{\displaystyle \Sigma } 6971:{\displaystyle \Gamma } 6931:{\displaystyle \Sigma } 6911:{\displaystyle \Gamma } 6649:{\displaystyle \Delta } 6629:{\displaystyle \Gamma } 6609:{\displaystyle \Delta } 6569:{\displaystyle \Gamma } 6492:{\displaystyle \Delta } 6452:{\displaystyle \Delta } 6391:{\displaystyle \vdash } 5637:Right structural rules 3958:{\displaystyle \vdash } 3465:{\displaystyle \vdash } 3434:{\displaystyle \vdash } 3412:§ Structural rules 3295:{\displaystyle \vdash } 1734:{\displaystyle \vdash } 476:{\displaystyle \vdash } 448:{\displaystyle n\geq 0} 429:are again formulae and 170:cut-elimination theorem 104:more on sets of rules. 12367: 12263: 12240: 12150: 12119: 12088: 12057: 12032: 12003: 11962: 11853: 11780: 11731: 11708: 11648: 11591: 11556: 11447: 11413: 11334: 11305: 11274: 11250: 11150: 11019: 10981: 10863: 10825: 10717: 10679: 10571: 10533: 10416: 10364: 10272: 10234: 10142: 10104: 9968: 9923: 9822: 9784: 9683: 9638: 9556: 9504: 9469: 9414: 9370: 9332: 9291: 9253: 9212: 9160: 9125: 9087: 9058: 9004: 8969: 8931: 8902: 8832: 8797: 8759: 8724: 8686: 8657: 8612: 8469: 8346: 8308: 8201: 8163: 8072: 8034: 7959: 7921: 7862: 7825: 7796: 7750: 7715: 7677: 7627: 7582: 7541: 7503: 7462: 7417: 7382: 7344: 7315: 7277:Law of excluded middle 7268: 7228: 7181: 7161: 7141: 7118: 7092: 7072: 7052: 7032: 7012: 6998:can be concluded from 6992: 6972: 6958:can be concluded from 6952: 6932: 6912: 6892: 6866: 6831: 6794: 6757: 6729: 6695: 6670: 6650: 6630: 6610: 6590: 6570: 6550: 6519: 6493: 6473: 6453: 6433: 6392: 6352: 6332: 6301: 6264: 6125: 5984: 5891: 5796: 5715: 5634:Left structural rules 5620: 5512: 5402: 5294: 5184: 5096: 5006: 4909: 4788: 4681: 4572: 4474: 4374: 4276: 4164: 4052: 3967:Weakening (Left/Right) 3959: 3939: 3916: 3893: 3870: 3847: 3824: 3799: 3762: 3742: 3722: 3702: 3682: 3662: 3642: 3622: 3583: 3563: 3536: 3516: 3494: 3466: 3435: 3404: 3384: 3350: 3330: 3296: 3200: 3158: 3073: 2986: 2892: 2787: 2693: 2588: 2485: 2353: 2309: 2270: 2226: 2197: 2168: 2123: 2069: 1991: 1911: 1827: 1735: 1709: 1607: 1544: 1408: 1276: 1177: 1095: 1065: 1032: 1009: 989: 969: 949: 922: 868: 773: 706: 651: 637:, etc., are all true, 631: 604: 574: 547: 524: 504: 477: 449: 423: 403: 373: 264: 241: 114:propositional calculus 13217:Introduction to logic 12950:Curry, Haskell Brooks 12810:Andrzej-Indrzejczak, 12620:, pp. 290, 297, 12368: 12264: 12241: 12151: 12120: 12089: 12058: 12033: 12004: 11963: 11854: 11781: 11732: 11730:{\displaystyle \bot } 11709: 11649: 11592: 11590:{\displaystyle \bot } 11557: 11448: 11414: 11335: 11306: 11275: 11251: 11151: 11020: 10982: 10864: 10826: 10718: 10680: 10572: 10534: 10417: 10365: 10273: 10235: 10143: 10105: 9969: 9924: 9823: 9785: 9684: 9639: 9557: 9505: 9470: 9415: 9371: 9333: 9292: 9254: 9213: 9161: 9126: 9088: 9059: 9005: 8970: 8932: 8903: 8833: 8798: 8760: 8725: 8687: 8658: 8613: 8470: 8347: 8309: 8202: 8164: 8073: 8035: 7960: 7922: 7863: 7826: 7797: 7751: 7716: 7678: 7628: 7583: 7542: 7504: 7463: 7418: 7383: 7345: 7316: 7269: 7229: 7182: 7162: 7142: 7119: 7093: 7073: 7053: 7033: 7013: 6993: 6973: 6953: 6933: 6913: 6893: 6867: 6832: 6795: 6758: 6730: 6696: 6671: 6651: 6631: 6611: 6591: 6571: 6551: 6520: 6494: 6474: 6454: 6434: 6393: 6353: 6333: 6302: 6265: 6126: 5985: 5892: 5797: 5716: 5621: 5513: 5403: 5295: 5185: 5097: 5007: 4910: 4789: 4682: 4573: 4475: 4375: 4277: 4165: 4053: 3960: 3940: 3917: 3894: 3871: 3848: 3825: 3800: 3763: 3743: 3723: 3703: 3683: 3663: 3643: 3623: 3584: 3564: 3537: 3517: 3495: 3467: 3436: 3414:), called contexts, 3405: 3385: 3351: 3331: 3310:on the left from the 3297: 3201: 3159: 3074: 2987: 2893: 2788: 2694: 2589: 2486: 2374:appears on the left. 2354: 2310: 2271: 2227: 2198: 2169: 2124: 2070: 1992: 1912: 1828: 1736: 1710: 1605: 1545: 1409: 1277: 1178: 1096: 1094:{\displaystyle B_{i}} 1066: 1064:{\displaystyle A_{i}} 1033: 1010: 990: 970: 950: 948:{\displaystyle B_{i}} 923: 921:{\displaystyle A_{i}} 869: 774: 707: 652: 632: 630:{\displaystyle A_{2}} 605: 603:{\displaystyle A_{1}} 575: 573:{\displaystyle A_{i}} 548: 525: 505: 503:{\displaystyle A_{i}} 478: 450: 424: 404: 402:{\displaystyle A_{i}} 374: 265: 242: 13323:Square of opposition 13120:Kleene, Stephen Cole 13098:Kleene, Stephen Cole 12616:, pp. 189–190, 12276: 12253: 12163: 12129: 12098: 12067: 12042: 12013: 11982: 11866: 11832: 11826:intuitionistic logic 11790:Substructural logics 11741: 11721: 11664: 11612: 11581: 11460: 11426: 11385: 11318: 11283: 11264: 11240: 11218:substructural logics 11032: 11000: 10876: 10844: 10730: 10716:{\displaystyle (PL)} 10698: 10584: 10570:{\displaystyle (CR)} 10552: 10429: 10397: 10285: 10271:{\displaystyle (PL)} 10253: 10155: 10141:{\displaystyle (CL)} 10123: 9981: 9942: 9835: 9821:{\displaystyle (PL)} 9803: 9696: 9657: 9569: 9537: 9482: 9453: 9383: 9351: 9304: 9290:{\displaystyle (PR)} 9272: 9225: 9193: 9138: 9124:{\displaystyle (WR)} 9106: 9071: 9042: 8982: 8968:{\displaystyle (WR)} 8950: 8915: 8886: 8810: 8796:{\displaystyle (PR)} 8778: 8737: 8705: 8670: 8641: 8495: 8359: 8327: 8214: 8182: 8085: 8053: 7972: 7940: 7875: 7846: 7806: 7777: 7728: 7714:{\displaystyle (CR)} 7696: 7640: 7601: 7554: 7540:{\displaystyle (PR)} 7522: 7475: 7436: 7395: 7363: 7328: 7299: 7246: 7218: 7171: 7151: 7131: 7102: 7082: 7062: 7042: 7022: 7002: 6982: 6962: 6942: 6922: 6902: 6876: 6845: 6804: 6767: 6739: 6708: 6680: 6676:must be false, i.e. 6660: 6640: 6620: 6600: 6596:suffice to conclude 6580: 6560: 6529: 6503: 6483: 6463: 6443: 6405: 6382: 6342: 6311: 6280: 6136: 5997: 5902: 5809: 5726: 5645: 5523: 5415: 5305: 5197: 5107: 5019: 4920: 4801: 4692: 4585: 4485: 4387: 4287: 4189: 4181:Right logical rules 4063: 4003: 3949: 3926: 3903: 3880: 3857: 3834: 3811: 3772: 3752: 3732: 3712: 3692: 3672: 3652: 3632: 3595: 3573: 3553: 3526: 3506: 3484: 3456: 3425: 3403:{\displaystyle \Pi } 3394: 3362: 3340: 3320: 3286: 3172: 3084: 2999: 2903: 2800: 2704: 2601: 2496: 2402: 2325: 2281: 2239: 2207: 2181: 2134: 2089: 2011: 1927: 1847: 1748: 1725: 1633: 1429: 1302: 1193: 1109: 1078: 1048: 1019: 999: 979: 959: 932: 905: 797: 722: 664: 641: 614: 587: 557: 534: 514: 487: 467: 433: 413: 386: 318: 254: 231: 69:first-order language 13142:Lemmon, Edward John 12755:is by assuming the 12325: 12284: 12201: 12171: 11914: 11874: 11802:substructural logic 11796:Substructural logic 11681: 11672: 11629: 11620: 11508: 11468: 9468:{\displaystyle (I)} 9057:{\displaystyle (I)} 8901:{\displaystyle (I)} 8656:{\displaystyle (I)} 7861:{\displaystyle (I)} 7314:{\displaystyle (I)} 7238:Example derivations 7193:automated deduction 6194: 6144: 6055: 6005: 5940: 5910: 5847: 5817: 5752: 5734: 5671: 5653: 5572: 5531: 5464: 5423: 5354: 5313: 5246: 5205: 5139: 5115: 5051: 5027: 4958: 4928: 4849: 4809: 4740: 4700: 4633: 4593: 4517: 4493: 4419: 4395: 4319: 4295: 4221: 4197: 4178:Left logical rules 4111: 4071: 4021: 4011: 3131: 3104: 3046: 3019: 2953: 2923: 2849: 2819: 2754: 2724: 2650: 2620: 2545: 2515: 2452: 2422: 1617:propositional logic 194:automated deduction 13251:"Sequent calculus" 13124:Mathematical logic 13030:10.1007/bf01201363 12994:10.1007/BF01201353 12852:intuitionistischer 12583:"PVS Prover Guide" 12575:Shankar, Natarajan 12555:, pp. 25–150. 12396:Resolution (logic) 12363: 12356: 12320: 12259: 12236: 12232: 12196: 12146: 12115: 12084: 12053: 12028: 11999: 11958: 11939: 11909: 11849: 11776: 11727: 11704: 11700: 11676: 11644: 11640: 11624: 11605:, with the axiom: 11599:absurdity constant 11587: 11577:One can introduce 11552: 11545: 11503: 11443: 11409: 11351:("Main Theorem"). 11330: 11301: 11270: 11246: 11146: 11015: 10977: 10859: 10821: 10713: 10675: 10567: 10529: 10412: 10360: 10268: 10230: 10138: 10100: 9964: 9919: 9818: 9780: 9679: 9634: 9552: 9500: 9465: 9410: 9366: 9328: 9287: 9249: 9208: 9156: 9121: 9083: 9054: 9000: 8965: 8927: 8898: 8828: 8793: 8755: 8720: 8682: 8653: 8608: 8465: 8342: 8304: 8197: 8159: 8068: 8030: 7955: 7917: 7858: 7821: 7792: 7746: 7711: 7673: 7623: 7578: 7537: 7499: 7458: 7413: 7378: 7340: 7311: 7264: 7224: 7177: 7157: 7137: 7114: 7088: 7068: 7048: 7028: 7008: 6988: 6968: 6948: 6928: 6908: 6888: 6862: 6827: 6790: 6753: 6725: 6691: 6666: 6646: 6626: 6606: 6586: 6566: 6546: 6515: 6489: 6469: 6449: 6429: 6388: 6348: 6328: 6297: 6260: 6239: 6189: 6121: 6100: 6050: 5980: 5959: 5935: 5887: 5866: 5842: 5792: 5771: 5747: 5711: 5690: 5666: 5616: 5597: 5567: 5508: 5489: 5459: 5398: 5379: 5349: 5290: 5271: 5241: 5180: 5161: 5134: 5092: 5073: 5046: 5002: 4983: 4953: 4905: 4886: 4844: 4784: 4765: 4735: 4677: 4658: 4628: 4568: 4542: 4512: 4470: 4444: 4414: 4370: 4344: 4314: 4272: 4246: 4216: 4160: 4136: 4106: 4048: 4034: 4016: 3955: 3938:{\displaystyle PR} 3935: 3915:{\displaystyle PL} 3912: 3892:{\displaystyle CR} 3889: 3869:{\displaystyle CL} 3866: 3846:{\displaystyle WR} 3843: 3823:{\displaystyle WL} 3820: 3795: 3758: 3738: 3718: 3698: 3678: 3658: 3638: 3618: 3579: 3559: 3532: 3512: 3490: 3462: 3431: 3400: 3380: 3346: 3326: 3292: 3196: 3154: 3150: 3126: 3069: 3065: 3041: 2982: 2978: 2948: 2888: 2884: 2844: 2783: 2779: 2749: 2689: 2685: 2645: 2584: 2580: 2540: 2481: 2477: 2447: 2349: 2305: 2266: 2222: 2193: 2164: 2119: 2065: 1987: 1907: 1823: 1731: 1705: 1608: 1540: 1404: 1272: 1173: 1091: 1061: 1028: 1005: 985: 965: 955:are formulae, and 945: 918: 864: 769: 702: 647: 627: 600: 570: 543: 520: 500: 473: 445: 419: 399: 369: 280:higher-order logic 260: 237: 134:mathematical logic 21:mathematical logic 13380: 13379: 13308:Diagrams in logic 13226:978-0-486-40687-9 13204:978-0-486-68370-6 13195:First-order logic 13182:978-0-19-289593-6 13148:. Thomas Nelson. 13133:978-0-486-42533-7 13111:978-0-923891-57-2 13089:978-3-642-86897-9 13046:Girard, Jean-Yves 12963:978-0-486-63462-3 12594:SRI International 12386:Cirquent calculus 12358: 12324: 12283: 12262:{\displaystyle y} 12234: 12200: 12170: 11941: 11913: 11873: 11702: 11680: 11671: 11642: 11628: 11619: 11547: 11507: 11467: 11345:cut is admissible 11249:{\displaystyle A} 11170: 11169: 10388: 10387: 10384: 10383: 9528: 9527: 9524: 9523: 9434: 9433: 9184: 9183: 9180: 9179: 9024: 9023: 8852: 8851: 8489: 8488: 7770: 7769: 7282:tertium non datur 7180:{\displaystyle A} 7160:{\displaystyle A} 7140:{\displaystyle A} 7091:{\displaystyle B} 7071:{\displaystyle A} 6991:{\displaystyle B} 6951:{\displaystyle A} 6830:{\displaystyle A} 6793:{\displaystyle A} 6669:{\displaystyle A} 6589:{\displaystyle A} 6472:{\displaystyle A} 6351:{\displaystyle y} 6273: 6272: 6241: 6193: 6143: 6102: 6054: 6004: 5961: 5939: 5909: 5868: 5846: 5816: 5773: 5751: 5733: 5692: 5670: 5652: 5629: 5628: 5599: 5571: 5530: 5491: 5463: 5422: 5381: 5353: 5312: 5273: 5245: 5204: 5163: 5138: 5114: 5075: 5050: 5026: 4985: 4957: 4927: 4888: 4848: 4808: 4767: 4739: 4699: 4660: 4632: 4592: 4544: 4516: 4492: 4446: 4418: 4394: 4346: 4318: 4294: 4248: 4220: 4196: 4173: 4172: 4138: 4110: 4070: 4036: 4020: 4010: 3798:{\displaystyle A} 3768:becomes bound in 3761:{\displaystyle t} 3741:{\displaystyle A} 3721:{\displaystyle x} 3701:{\displaystyle t} 3681:{\displaystyle A} 3661:{\displaystyle x} 3641:{\displaystyle t} 3621:{\displaystyle A} 3542:denote variables. 3535:{\displaystyle y} 3515:{\displaystyle x} 3493:{\displaystyle t} 3349:{\displaystyle B} 3329:{\displaystyle A} 3209: 3208: 3152: 3130: 3103: 3096: 3067: 3045: 3018: 3011: 2980: 2952: 2922: 2915: 2886: 2848: 2818: 2812: 2781: 2753: 2723: 2716: 2687: 2649: 2619: 2613: 2582: 2544: 2514: 2508: 2479: 2451: 2421: 2414: 1619:, similar to the 1291:classical context 1008:{\displaystyle B} 988:{\displaystyle k} 968:{\displaystyle n} 650:{\displaystyle B} 523:{\displaystyle B} 422:{\displaystyle B} 307:Natural deduction 295:natural deduction 291:deduction theorem 263:{\displaystyle B} 240:{\displaystyle B} 154:first-order logic 150:natural deduction 92:Natural deduction 55:earlier style of 35:is a conditional 13410: 13375: 13358:Sequent calculus 13302: 13295: 13288: 13279: 13278: 13264: 13230: 13208: 13186: 13159: 13137: 13115: 13093: 13067: 13055: 13052:Proofs and Types 13041: 13005: 12967: 12945: 12912: 12905: 12899: 12845: 12839: 12833: 12827: 12821: 12815: 12808: 12802: 12795: 12789: 12788: 12782: 12776:Tait WW (2010). 12773: 12767: 12745: 12739: 12733: 12722: 12716: 12710: 12704: 12698: 12692: 12686: 12671: 12665: 12655: 12649: 12643: 12637: 12610: 12604: 12603: 12601: 12600: 12587: 12571: 12565: 12562: 12556: 12542: 12536: 12526: 12520: 12514: 12508: 12502: 12496: 12490: 12484: 12478: 12472: 12466: 12460: 12454: 12445: 12439: 12430: 12420: 12372: 12370: 12369: 12364: 12359: 12357: 12355: 12321: 12319: 12306: 12280: 12268: 12266: 12265: 12260: 12245: 12243: 12242: 12237: 12235: 12233: 12231: 12197: 12195: 12167: 12155: 12153: 12152: 12147: 12139: 12124: 12122: 12121: 12116: 12108: 12093: 12091: 12090: 12085: 12077: 12062: 12060: 12059: 12054: 12049: 12037: 12035: 12034: 12029: 12008: 12006: 12005: 12000: 11992: 11967: 11965: 11964: 11959: 11951: 11942: 11940: 11938: 11910: 11908: 11870: 11858: 11856: 11855: 11850: 11842: 11810:computer science 11785: 11783: 11782: 11777: 11736: 11734: 11733: 11728: 11713: 11711: 11710: 11705: 11703: 11701: 11699: 11677: 11675: 11668: 11653: 11651: 11650: 11645: 11643: 11641: 11639: 11625: 11623: 11616: 11596: 11594: 11593: 11588: 11561: 11559: 11558: 11553: 11548: 11546: 11544: 11504: 11502: 11464: 11452: 11450: 11449: 11444: 11436: 11418: 11416: 11415: 11410: 11339: 11337: 11336: 11331: 11310: 11308: 11307: 11302: 11279: 11277: 11276: 11271: 11255: 11253: 11252: 11247: 11194:Structural rules 11188:analytic tableau 11155: 11153: 11152: 11147: 11145: 11141: 11140: 11136: 11126: 11122: 11112: 11108: 11077: 11073: 11072: 11068: 11024: 11022: 11021: 11016: 10986: 10984: 10983: 10978: 10976: 10972: 10962: 10958: 10948: 10944: 10913: 10909: 10908: 10904: 10868: 10866: 10865: 10860: 10830: 10828: 10827: 10822: 10811: 10807: 10797: 10793: 10767: 10763: 10762: 10758: 10722: 10720: 10719: 10714: 10684: 10682: 10681: 10676: 10665: 10661: 10660: 10656: 10627: 10623: 10613: 10609: 10576: 10574: 10573: 10568: 10538: 10536: 10535: 10530: 10510: 10506: 10505: 10501: 10472: 10468: 10458: 10454: 10421: 10419: 10418: 10413: 10369: 10367: 10366: 10361: 10350: 10346: 10328: 10324: 10314: 10310: 10277: 10275: 10274: 10269: 10239: 10237: 10236: 10231: 10220: 10216: 10206: 10202: 10176: 10172: 10147: 10145: 10144: 10139: 10109: 10107: 10106: 10101: 10090: 10086: 10076: 10072: 10046: 10042: 10032: 10028: 10002: 9998: 9973: 9971: 9970: 9965: 9960: 9959: 9928: 9926: 9925: 9920: 9900: 9896: 9886: 9882: 9856: 9852: 9827: 9825: 9824: 9819: 9789: 9787: 9786: 9781: 9770: 9766: 9756: 9752: 9717: 9713: 9688: 9686: 9685: 9680: 9675: 9674: 9643: 9641: 9640: 9635: 9624: 9620: 9590: 9586: 9561: 9559: 9558: 9553: 9509: 9507: 9506: 9501: 9474: 9472: 9471: 9466: 9441: 9419: 9417: 9416: 9411: 9375: 9373: 9372: 9367: 9337: 9335: 9334: 9329: 9296: 9294: 9293: 9288: 9258: 9256: 9255: 9250: 9217: 9215: 9214: 9209: 9165: 9163: 9162: 9157: 9130: 9128: 9127: 9122: 9092: 9090: 9089: 9084: 9063: 9061: 9060: 9055: 9031: 9009: 9007: 9006: 9001: 8974: 8972: 8971: 8966: 8936: 8934: 8933: 8928: 8907: 8905: 8904: 8899: 8875: 8871: 8867: 8863: 8859: 8837: 8835: 8834: 8829: 8802: 8800: 8799: 8794: 8764: 8762: 8761: 8756: 8729: 8727: 8726: 8721: 8691: 8689: 8688: 8683: 8662: 8660: 8659: 8654: 8629: 8625: 8621: 8617: 8615: 8614: 8609: 8607: 8606: 8602: 8601: 8597: 8587: 8583: 8573: 8569: 8538: 8534: 8533: 8529: 8474: 8472: 8471: 8466: 8464: 8460: 8459: 8455: 8411: 8407: 8406: 8402: 8351: 8349: 8348: 8343: 8313: 8311: 8310: 8305: 8303: 8299: 8266: 8262: 8261: 8257: 8206: 8204: 8203: 8198: 8168: 8166: 8165: 8160: 8158: 8154: 8121: 8117: 8077: 8075: 8074: 8069: 8039: 8037: 8036: 8031: 8008: 8004: 7964: 7962: 7961: 7956: 7926: 7924: 7923: 7918: 7867: 7865: 7864: 7859: 7834: 7830: 7828: 7827: 7822: 7801: 7799: 7798: 7793: 7755: 7753: 7752: 7747: 7720: 7718: 7717: 7712: 7682: 7680: 7679: 7674: 7632: 7630: 7629: 7624: 7619: 7618: 7587: 7585: 7584: 7579: 7546: 7544: 7543: 7538: 7508: 7506: 7505: 7500: 7467: 7465: 7464: 7459: 7454: 7453: 7422: 7420: 7419: 7414: 7387: 7385: 7384: 7379: 7349: 7347: 7346: 7341: 7320: 7318: 7317: 7312: 7287: 7274:", known as the 7273: 7271: 7270: 7265: 7233: 7231: 7230: 7225: 7186: 7184: 7183: 7178: 7166: 7164: 7163: 7158: 7146: 7144: 7143: 7138: 7123: 7121: 7120: 7115: 7097: 7095: 7094: 7089: 7077: 7075: 7074: 7069: 7057: 7055: 7054: 7049: 7037: 7035: 7034: 7029: 7017: 7015: 7014: 7009: 6997: 6995: 6994: 6989: 6977: 6975: 6974: 6969: 6957: 6955: 6954: 6949: 6937: 6935: 6934: 6929: 6917: 6915: 6914: 6909: 6897: 6895: 6894: 6889: 6871: 6869: 6868: 6863: 6855: 6836: 6834: 6833: 6828: 6820: 6799: 6797: 6796: 6791: 6783: 6762: 6760: 6759: 6754: 6749: 6734: 6732: 6731: 6726: 6718: 6700: 6698: 6697: 6692: 6687: 6675: 6673: 6672: 6667: 6655: 6653: 6652: 6647: 6635: 6633: 6632: 6627: 6615: 6613: 6612: 6607: 6595: 6593: 6592: 6587: 6575: 6573: 6572: 6567: 6556:states that, if 6555: 6553: 6552: 6547: 6539: 6524: 6522: 6521: 6516: 6498: 6496: 6495: 6490: 6478: 6476: 6475: 6470: 6458: 6456: 6455: 6450: 6438: 6436: 6435: 6430: 6425: 6424: 6415: 6397: 6395: 6394: 6389: 6357: 6355: 6354: 6349: 6337: 6335: 6334: 6329: 6321: 6306: 6304: 6303: 6298: 6290: 6269: 6267: 6266: 6261: 6256: 6255: 6242: 6240: 6238: 6237: 6236: 6212: 6211: 6190: 6188: 6187: 6186: 6162: 6161: 6140: 6130: 6128: 6127: 6122: 6117: 6116: 6103: 6101: 6099: 6092: 6091: 6067: 6066: 6051: 6049: 6042: 6041: 6017: 6016: 6001: 5989: 5987: 5986: 5981: 5976: 5975: 5962: 5960: 5958: 5936: 5934: 5906: 5896: 5894: 5893: 5888: 5883: 5882: 5869: 5867: 5865: 5843: 5841: 5813: 5801: 5799: 5798: 5793: 5788: 5787: 5774: 5772: 5770: 5748: 5746: 5730: 5720: 5718: 5717: 5712: 5707: 5706: 5693: 5691: 5689: 5667: 5665: 5649: 5631: 5630: 5625: 5623: 5622: 5617: 5609: 5600: 5598: 5596: 5568: 5566: 5553: 5527: 5517: 5515: 5514: 5509: 5501: 5492: 5490: 5488: 5460: 5458: 5445: 5419: 5407: 5405: 5404: 5399: 5391: 5382: 5380: 5378: 5350: 5348: 5335: 5309: 5299: 5297: 5296: 5291: 5283: 5274: 5272: 5270: 5242: 5240: 5227: 5201: 5189: 5187: 5186: 5181: 5173: 5164: 5162: 5160: 5135: 5133: 5111: 5101: 5099: 5098: 5093: 5085: 5076: 5074: 5072: 5047: 5045: 5023: 5011: 5009: 5008: 5003: 4995: 4986: 4984: 4982: 4954: 4952: 4924: 4914: 4912: 4911: 4906: 4898: 4889: 4887: 4885: 4845: 4843: 4805: 4793: 4791: 4790: 4785: 4777: 4768: 4766: 4764: 4736: 4734: 4696: 4686: 4684: 4683: 4678: 4670: 4661: 4659: 4657: 4629: 4627: 4589: 4577: 4575: 4574: 4569: 4564: 4563: 4554: 4545: 4543: 4541: 4513: 4511: 4489: 4479: 4477: 4476: 4471: 4466: 4465: 4456: 4447: 4445: 4443: 4415: 4413: 4391: 4379: 4377: 4376: 4371: 4366: 4365: 4356: 4347: 4345: 4343: 4315: 4313: 4291: 4281: 4279: 4278: 4273: 4268: 4267: 4258: 4249: 4247: 4245: 4217: 4215: 4193: 4175: 4174: 4169: 4167: 4166: 4161: 4156: 4155: 4139: 4137: 4135: 4107: 4105: 4067: 4057: 4055: 4054: 4049: 4037: 4035: 4033: 4017: 4015: 4007: 3989: 3988: 3964: 3962: 3961: 3956: 3944: 3942: 3941: 3936: 3921: 3919: 3918: 3913: 3898: 3896: 3895: 3890: 3875: 3873: 3872: 3867: 3852: 3850: 3849: 3844: 3829: 3827: 3826: 3821: 3804: 3802: 3801: 3796: 3788: 3767: 3765: 3764: 3759: 3747: 3745: 3744: 3739: 3727: 3725: 3724: 3719: 3707: 3705: 3704: 3699: 3687: 3685: 3684: 3679: 3667: 3665: 3664: 3659: 3647: 3645: 3644: 3639: 3627: 3625: 3624: 3619: 3611: 3588: 3586: 3585: 3580: 3568: 3566: 3565: 3560: 3541: 3539: 3538: 3533: 3521: 3519: 3518: 3513: 3499: 3497: 3496: 3491: 3471: 3469: 3468: 3463: 3440: 3438: 3437: 3432: 3409: 3407: 3406: 3401: 3389: 3387: 3386: 3381: 3355: 3353: 3352: 3347: 3335: 3333: 3332: 3327: 3306:, separates the 3301: 3299: 3298: 3293: 3205: 3203: 3202: 3197: 3163: 3161: 3160: 3155: 3153: 3151: 3149: 3127: 3125: 3100: 3097: 3094: 3078: 3076: 3075: 3070: 3068: 3066: 3064: 3042: 3040: 3015: 3012: 3009: 2991: 2989: 2988: 2983: 2981: 2979: 2977: 2949: 2947: 2919: 2916: 2913: 2897: 2895: 2894: 2889: 2887: 2885: 2883: 2845: 2843: 2815: 2813: 2810: 2792: 2790: 2789: 2784: 2782: 2780: 2778: 2750: 2748: 2720: 2717: 2714: 2698: 2696: 2695: 2690: 2688: 2686: 2684: 2646: 2644: 2616: 2614: 2611: 2593: 2591: 2590: 2585: 2583: 2581: 2579: 2541: 2539: 2511: 2509: 2506: 2490: 2488: 2487: 2482: 2480: 2478: 2476: 2448: 2446: 2418: 2415: 2412: 2388: 2387: 2358: 2356: 2355: 2350: 2314: 2312: 2311: 2306: 2275: 2273: 2272: 2267: 2231: 2229: 2228: 2223: 2202: 2200: 2199: 2194: 2173: 2171: 2170: 2165: 2128: 2126: 2125: 2120: 2074: 2072: 2071: 2066: 1996: 1994: 1993: 1988: 1916: 1914: 1913: 1908: 1832: 1830: 1829: 1824: 1740: 1738: 1737: 1732: 1720:turnstile symbol 1714: 1712: 1711: 1706: 1561:De Morgan's laws 1549: 1547: 1546: 1541: 1536: 1535: 1514: 1513: 1498: 1497: 1482: 1481: 1463: 1462: 1450: 1449: 1413: 1411: 1410: 1405: 1403: 1402: 1384: 1383: 1371: 1370: 1358: 1357: 1336: 1335: 1320: 1319: 1281: 1279: 1278: 1273: 1268: 1267: 1249: 1248: 1230: 1229: 1211: 1210: 1182: 1180: 1179: 1174: 1172: 1171: 1153: 1152: 1140: 1139: 1121: 1120: 1100: 1098: 1097: 1092: 1090: 1089: 1070: 1068: 1067: 1062: 1060: 1059: 1037: 1035: 1034: 1029: 1014: 1012: 1011: 1006: 994: 992: 991: 986: 974: 972: 971: 966: 954: 952: 951: 946: 944: 943: 927: 925: 924: 919: 917: 916: 873: 871: 870: 865: 860: 859: 841: 840: 828: 827: 809: 808: 778: 776: 775: 770: 759: 758: 740: 739: 711: 709: 708: 703: 695: 694: 676: 675: 656: 654: 653: 648: 636: 634: 633: 628: 626: 625: 609: 607: 606: 601: 599: 598: 579: 577: 576: 571: 569: 568: 552: 550: 549: 544: 529: 527: 526: 521: 509: 507: 506: 501: 499: 498: 482: 480: 479: 474: 454: 452: 451: 446: 428: 426: 425: 420: 408: 406: 405: 400: 398: 397: 378: 376: 375: 370: 362: 361: 343: 342: 330: 329: 269: 267: 266: 261: 246: 244: 243: 238: 25:sequent calculus 13418: 13417: 13413: 13412: 13411: 13409: 13408: 13407: 13398:Logical calculi 13383: 13382: 13381: 13376: 13367: 13328:Porphyrian tree 13309: 13306: 13249: 13237: 13227: 13205: 13183: 13175:. p. 431. 13156: 13146:Beginning logic 13134: 13112: 13090: 13064: 12964: 12942: 12926:Buss, Samuel R. 12921: 12916: 12915: 12906: 12902: 12846: 12842: 12834: 12830: 12822: 12818: 12809: 12805: 12797:Jan von Plato, 12796: 12792: 12780: 12774: 12770: 12746: 12742: 12734: 12725: 12717: 12713: 12705: 12701: 12693: 12689: 12672: 12668: 12656: 12652: 12644: 12640: 12628:, p. 385, 12624:, p. 441, 12611: 12607: 12598: 12596: 12585: 12579:Rushby, John M. 12572: 12568: 12563: 12559: 12543: 12539: 12527: 12523: 12515: 12511: 12503: 12499: 12491: 12487: 12479: 12475: 12467: 12463: 12455: 12448: 12440: 12433: 12421: 12414: 12409: 12382: 12327: 12322: 12302: 12286: 12281: 12279: 12277: 12274: 12273: 12254: 12251: 12250: 12203: 12198: 12173: 12168: 12166: 12164: 12161: 12160: 12135: 12130: 12127: 12126: 12104: 12099: 12096: 12095: 12073: 12068: 12065: 12064: 12045: 12043: 12040: 12039: 12014: 12011: 12010: 11988: 11983: 11980: 11979: 11947: 11916: 11911: 11876: 11871: 11869: 11867: 11864: 11863: 11838: 11833: 11830: 11829: 11822: 11798: 11792: 11742: 11739: 11738: 11722: 11719: 11718: 11683: 11678: 11674: 11669: 11667: 11665: 11662: 11661: 11631: 11626: 11622: 11617: 11615: 11613: 11610: 11609: 11582: 11579: 11578: 11575: 11510: 11505: 11470: 11465: 11463: 11461: 11458: 11457: 11432: 11427: 11424: 11423: 11386: 11383: 11382: 11365: 11357: 11319: 11316: 11315: 11284: 11281: 11280: 11265: 11262: 11261: 11241: 11238: 11237: 11226: 11196: 11184: 11095: 11091: 11090: 11086: 11085: 11081: 11058: 11054: 11047: 11043: 11042: 11038: 11033: 11030: 11029: 11001: 10998: 10997: 10931: 10927: 10926: 10922: 10921: 10917: 10894: 10890: 10883: 10879: 10877: 10874: 10873: 10845: 10842: 10841: 10780: 10776: 10775: 10771: 10748: 10744: 10737: 10733: 10731: 10728: 10727: 10699: 10696: 10695: 10646: 10642: 10635: 10631: 10596: 10592: 10591: 10587: 10585: 10582: 10581: 10553: 10550: 10549: 10491: 10487: 10480: 10476: 10441: 10437: 10436: 10432: 10430: 10427: 10426: 10398: 10395: 10394: 10336: 10332: 10297: 10293: 10292: 10288: 10286: 10283: 10282: 10254: 10251: 10250: 10189: 10185: 10184: 10180: 10162: 10158: 10156: 10153: 10152: 10124: 10121: 10120: 10059: 10055: 10054: 10050: 10015: 10011: 10010: 10006: 9988: 9984: 9982: 9979: 9978: 9955: 9951: 9943: 9940: 9939: 9869: 9865: 9864: 9860: 9842: 9838: 9836: 9833: 9832: 9804: 9801: 9800: 9739: 9735: 9734: 9730: 9703: 9699: 9697: 9694: 9693: 9670: 9666: 9658: 9655: 9654: 9607: 9603: 9576: 9572: 9570: 9567: 9566: 9538: 9535: 9534: 9483: 9480: 9479: 9454: 9451: 9450: 9384: 9381: 9380: 9352: 9349: 9348: 9305: 9302: 9301: 9273: 9270: 9269: 9226: 9223: 9222: 9194: 9191: 9190: 9139: 9136: 9135: 9107: 9104: 9103: 9072: 9069: 9068: 9043: 9040: 9039: 8983: 8980: 8979: 8951: 8948: 8947: 8916: 8913: 8912: 8887: 8884: 8883: 8811: 8808: 8807: 8779: 8776: 8775: 8738: 8735: 8734: 8706: 8703: 8702: 8671: 8668: 8667: 8642: 8639: 8638: 8556: 8552: 8551: 8547: 8546: 8542: 8519: 8515: 8508: 8504: 8503: 8499: 8498: 8496: 8493: 8492: 8436: 8432: 8425: 8421: 8383: 8379: 8372: 8368: 8360: 8357: 8356: 8328: 8325: 8324: 8280: 8276: 8238: 8234: 8227: 8223: 8215: 8212: 8211: 8183: 8180: 8179: 8135: 8131: 8098: 8094: 8086: 8083: 8082: 8054: 8051: 8050: 7985: 7981: 7973: 7970: 7969: 7941: 7938: 7937: 7876: 7873: 7872: 7847: 7844: 7843: 7807: 7804: 7803: 7778: 7775: 7774: 7729: 7726: 7725: 7697: 7694: 7693: 7641: 7638: 7637: 7614: 7610: 7602: 7599: 7598: 7555: 7552: 7551: 7523: 7520: 7519: 7476: 7473: 7472: 7449: 7445: 7437: 7434: 7433: 7396: 7393: 7392: 7364: 7361: 7360: 7329: 7326: 7325: 7300: 7297: 7296: 7247: 7244: 7243: 7240: 7219: 7216: 7215: 7209:atomic formulas 7172: 7169: 7168: 7152: 7149: 7148: 7132: 7129: 7128: 7103: 7100: 7099: 7083: 7080: 7079: 7063: 7060: 7059: 7043: 7040: 7039: 7023: 7020: 7019: 7003: 7000: 6999: 6983: 6980: 6979: 6963: 6960: 6959: 6943: 6940: 6939: 6923: 6920: 6919: 6903: 6900: 6899: 6877: 6874: 6873: 6851: 6846: 6843: 6842: 6816: 6805: 6802: 6801: 6779: 6768: 6765: 6764: 6745: 6740: 6737: 6736: 6714: 6709: 6706: 6705: 6683: 6681: 6678: 6677: 6661: 6658: 6657: 6641: 6638: 6637: 6621: 6618: 6617: 6601: 6598: 6597: 6581: 6578: 6577: 6561: 6558: 6557: 6535: 6530: 6527: 6526: 6504: 6501: 6500: 6484: 6481: 6480: 6464: 6461: 6460: 6444: 6441: 6440: 6420: 6416: 6411: 6406: 6403: 6402: 6383: 6380: 6379: 6365: 6343: 6340: 6339: 6338:, the variable 6317: 6312: 6309: 6308: 6286: 6281: 6278: 6277: 6248: 6247: 6232: 6228: 6207: 6203: 6196: 6191: 6182: 6178: 6157: 6153: 6146: 6141: 6139: 6137: 6134: 6133: 6109: 6108: 6087: 6083: 6062: 6058: 6057: 6052: 6037: 6033: 6012: 6008: 6007: 6002: 6000: 5998: 5995: 5994: 5968: 5967: 5942: 5937: 5912: 5907: 5905: 5903: 5900: 5899: 5875: 5874: 5849: 5844: 5819: 5814: 5812: 5810: 5807: 5806: 5780: 5779: 5754: 5749: 5736: 5731: 5729: 5727: 5724: 5723: 5699: 5698: 5673: 5668: 5655: 5650: 5648: 5646: 5643: 5642: 5605: 5574: 5569: 5549: 5533: 5528: 5526: 5524: 5521: 5520: 5497: 5466: 5461: 5441: 5425: 5420: 5418: 5416: 5413: 5412: 5387: 5356: 5351: 5331: 5315: 5310: 5308: 5306: 5303: 5302: 5279: 5248: 5243: 5223: 5207: 5202: 5200: 5198: 5195: 5194: 5169: 5141: 5136: 5117: 5112: 5110: 5108: 5105: 5104: 5081: 5053: 5048: 5029: 5024: 5022: 5020: 5017: 5016: 4991: 4960: 4955: 4930: 4925: 4923: 4921: 4918: 4917: 4894: 4851: 4846: 4811: 4806: 4804: 4802: 4799: 4798: 4773: 4742: 4737: 4702: 4697: 4695: 4693: 4690: 4689: 4666: 4635: 4630: 4595: 4590: 4588: 4586: 4583: 4582: 4559: 4555: 4550: 4519: 4514: 4495: 4490: 4488: 4486: 4483: 4482: 4461: 4457: 4452: 4421: 4416: 4397: 4392: 4390: 4388: 4385: 4384: 4361: 4357: 4352: 4321: 4316: 4297: 4292: 4290: 4288: 4285: 4284: 4263: 4259: 4254: 4223: 4218: 4199: 4194: 4192: 4190: 4187: 4186: 4145: 4144: 4113: 4108: 4073: 4068: 4066: 4064: 4061: 4060: 4023: 4018: 4013: 4008: 4006: 4004: 4001: 4000: 3950: 3947: 3946: 3927: 3924: 3923: 3904: 3901: 3900: 3881: 3878: 3877: 3858: 3855: 3854: 3835: 3832: 3831: 3812: 3809: 3808: 3784: 3773: 3770: 3769: 3753: 3750: 3749: 3733: 3730: 3729: 3713: 3710: 3709: 3693: 3690: 3689: 3673: 3670: 3669: 3653: 3650: 3649: 3633: 3630: 3629: 3607: 3596: 3593: 3592: 3574: 3571: 3570: 3554: 3551: 3550: 3527: 3524: 3523: 3507: 3504: 3503: 3485: 3482: 3481: 3457: 3454: 3453: 3426: 3423: 3422: 3395: 3392: 3391: 3363: 3360: 3359: 3341: 3338: 3337: 3321: 3318: 3317: 3287: 3284: 3283: 3277: 3275:Inference rules 3261: 3237: 3173: 3170: 3169: 3133: 3128: 3106: 3101: 3099: 3093: 3085: 3082: 3081: 3048: 3043: 3021: 3016: 3014: 3008: 3000: 2997: 2996: 2955: 2950: 2925: 2920: 2918: 2912: 2904: 2901: 2900: 2851: 2846: 2821: 2816: 2814: 2809: 2801: 2798: 2797: 2756: 2751: 2726: 2721: 2719: 2713: 2705: 2702: 2701: 2652: 2647: 2622: 2617: 2615: 2610: 2602: 2599: 2598: 2547: 2542: 2517: 2512: 2510: 2505: 2497: 2494: 2493: 2454: 2449: 2424: 2419: 2417: 2411: 2403: 2400: 2399: 2326: 2323: 2322: 2282: 2279: 2278: 2240: 2237: 2236: 2208: 2205: 2204: 2182: 2179: 2178: 2135: 2132: 2131: 2090: 2087: 2086: 2012: 2009: 2008: 1928: 1925: 1924: 1848: 1845: 1844: 1749: 1746: 1745: 1726: 1723: 1722: 1634: 1631: 1630: 1613: 1611:Reduction trees 1600: 1587: 1578:excluded middle 1573: 1531: 1527: 1509: 1505: 1493: 1489: 1477: 1473: 1458: 1454: 1445: 1441: 1430: 1427: 1426: 1398: 1394: 1379: 1375: 1366: 1362: 1353: 1349: 1331: 1327: 1315: 1311: 1303: 1300: 1299: 1263: 1259: 1244: 1240: 1225: 1221: 1206: 1202: 1194: 1191: 1190: 1167: 1163: 1148: 1144: 1135: 1131: 1116: 1112: 1110: 1107: 1106: 1085: 1081: 1079: 1076: 1075: 1055: 1051: 1049: 1046: 1045: 1020: 1017: 1016: 1000: 997: 996: 980: 977: 976: 960: 957: 956: 939: 935: 933: 930: 929: 912: 908: 906: 903: 902: 881:are called the 855: 851: 836: 832: 823: 819: 804: 800: 798: 795: 794: 788: 754: 750: 735: 731: 723: 720: 719: 690: 686: 671: 667: 665: 662: 661: 642: 639: 638: 621: 617: 615: 612: 611: 594: 590: 588: 585: 584: 564: 560: 558: 555: 554: 535: 532: 531: 515: 512: 511: 494: 490: 488: 485: 484: 468: 465: 464: 434: 431: 430: 414: 411: 410: 393: 389: 387: 384: 383: 357: 353: 338: 334: 325: 321: 319: 316: 315: 309: 303: 255: 252: 251: 232: 229: 228: 216:in the system, 208: 202: 190:Gentzen systems 126: 53:David Hilbert's 45:Gerhard Gentzen 17: 12: 11: 5: 13416: 13406: 13405: 13400: 13395: 13378: 13377: 13370: 13368: 13366: 13365: 13360: 13355: 13350: 13345: 13340: 13335: 13330: 13325: 13320: 13314: 13311: 13310: 13305: 13304: 13297: 13290: 13282: 13276: 13275: 13270: 13265: 13247: 13236: 13235:External links 13233: 13232: 13231: 13225: 13209: 13203: 13187: 13181: 13160: 13154: 13138: 13132: 13116: 13110: 13094: 13088: 13072:Hilbert, David 13068: 13062: 13042: 13024:(3): 405–431. 13006: 12988:(2): 176–210. 12968: 12962: 12946: 12940: 12920: 12917: 12914: 12913: 12900: 12876:intuitionistic 12840: 12828: 12816: 12803: 12790: 12768: 12740: 12723: 12721:, p. 441. 12711: 12699: 12687: 12666: 12650: 12638: 12636:, p. 180. 12605: 12566: 12557: 12537: 12521: 12509: 12497: 12485: 12473: 12461: 12446: 12431: 12411: 12410: 12408: 12405: 12404: 12403: 12398: 12393: 12388: 12381: 12378: 12374: 12373: 12362: 12354: 12351: 12348: 12345: 12342: 12339: 12336: 12333: 12330: 12318: 12315: 12312: 12309: 12305: 12301: 12298: 12295: 12292: 12289: 12258: 12247: 12246: 12230: 12227: 12224: 12221: 12218: 12215: 12212: 12209: 12206: 12194: 12191: 12188: 12185: 12182: 12179: 12176: 12145: 12142: 12138: 12134: 12114: 12111: 12107: 12103: 12083: 12080: 12076: 12072: 12052: 12048: 12027: 12024: 12021: 12018: 11998: 11995: 11991: 11987: 11969: 11968: 11957: 11954: 11950: 11946: 11937: 11934: 11931: 11928: 11925: 11922: 11919: 11907: 11904: 11901: 11898: 11895: 11891: 11888: 11885: 11882: 11879: 11848: 11845: 11841: 11837: 11821: 11818: 11794:Main article: 11791: 11788: 11775: 11772: 11769: 11766: 11763: 11759: 11755: 11752: 11749: 11746: 11726: 11715: 11714: 11698: 11695: 11692: 11689: 11686: 11655: 11654: 11637: 11634: 11586: 11574: 11571: 11563: 11562: 11551: 11543: 11540: 11537: 11534: 11531: 11528: 11525: 11522: 11519: 11516: 11513: 11501: 11498: 11495: 11492: 11489: 11485: 11482: 11479: 11476: 11473: 11442: 11439: 11435: 11431: 11408: 11405: 11402: 11399: 11396: 11393: 11390: 11364: 11361: 11356: 11353: 11329: 11326: 11323: 11312:if and only if 11300: 11297: 11294: 11291: 11288: 11269: 11245: 11225: 11222: 11209:also consider 11195: 11192: 11183: 11180: 11168: 11167: 11164: 11160: 11159: 11156: 11144: 11139: 11135: 11132: 11129: 11125: 11121: 11118: 11115: 11111: 11107: 11104: 11101: 11098: 11094: 11089: 11084: 11080: 11076: 11071: 11067: 11064: 11061: 11057: 11053: 11050: 11046: 11041: 11037: 11026: 11025: 11014: 11011: 11008: 11005: 10995: 10991: 10990: 10987: 10975: 10971: 10968: 10965: 10961: 10957: 10954: 10951: 10947: 10943: 10940: 10937: 10934: 10930: 10925: 10920: 10916: 10912: 10907: 10903: 10900: 10897: 10893: 10889: 10886: 10882: 10870: 10869: 10858: 10855: 10852: 10849: 10839: 10835: 10834: 10831: 10820: 10817: 10814: 10810: 10806: 10803: 10800: 10796: 10792: 10789: 10786: 10783: 10779: 10774: 10770: 10766: 10761: 10757: 10754: 10751: 10747: 10743: 10740: 10736: 10724: 10723: 10712: 10709: 10706: 10703: 10693: 10689: 10688: 10685: 10674: 10671: 10668: 10664: 10659: 10655: 10652: 10649: 10645: 10641: 10638: 10634: 10630: 10626: 10622: 10619: 10616: 10612: 10608: 10605: 10602: 10599: 10595: 10590: 10578: 10577: 10566: 10563: 10560: 10557: 10547: 10543: 10542: 10539: 10528: 10525: 10522: 10519: 10516: 10513: 10509: 10504: 10500: 10497: 10494: 10490: 10486: 10483: 10479: 10475: 10471: 10467: 10464: 10461: 10457: 10453: 10450: 10447: 10444: 10440: 10435: 10423: 10422: 10411: 10408: 10405: 10402: 10392: 10389: 10386: 10385: 10382: 10381: 10378: 10374: 10373: 10370: 10359: 10356: 10353: 10349: 10345: 10342: 10339: 10335: 10331: 10327: 10323: 10320: 10317: 10313: 10309: 10306: 10303: 10300: 10296: 10291: 10279: 10278: 10267: 10264: 10261: 10258: 10248: 10244: 10243: 10240: 10229: 10226: 10223: 10219: 10215: 10212: 10209: 10205: 10201: 10198: 10195: 10192: 10188: 10183: 10179: 10175: 10171: 10168: 10165: 10161: 10149: 10148: 10137: 10134: 10131: 10128: 10118: 10114: 10113: 10110: 10099: 10096: 10093: 10089: 10085: 10082: 10079: 10075: 10071: 10068: 10065: 10062: 10058: 10053: 10049: 10045: 10041: 10038: 10035: 10031: 10027: 10024: 10021: 10018: 10014: 10009: 10005: 10001: 9997: 9994: 9991: 9987: 9975: 9974: 9963: 9958: 9954: 9950: 9947: 9937: 9933: 9932: 9929: 9918: 9915: 9912: 9909: 9906: 9903: 9899: 9895: 9892: 9889: 9885: 9881: 9878: 9875: 9872: 9868: 9863: 9859: 9855: 9851: 9848: 9845: 9841: 9829: 9828: 9817: 9814: 9811: 9808: 9798: 9794: 9793: 9790: 9779: 9776: 9773: 9769: 9765: 9762: 9759: 9755: 9751: 9748: 9745: 9742: 9738: 9733: 9729: 9726: 9723: 9720: 9716: 9712: 9709: 9706: 9702: 9690: 9689: 9678: 9673: 9669: 9665: 9662: 9652: 9648: 9647: 9644: 9633: 9630: 9627: 9623: 9619: 9616: 9613: 9610: 9606: 9602: 9599: 9596: 9593: 9589: 9585: 9582: 9579: 9575: 9563: 9562: 9551: 9548: 9545: 9542: 9532: 9529: 9526: 9525: 9522: 9521: 9518: 9514: 9513: 9510: 9499: 9496: 9493: 9490: 9487: 9476: 9475: 9464: 9461: 9458: 9448: 9445: 9438: 9435: 9432: 9431: 9428: 9424: 9423: 9420: 9409: 9406: 9403: 9400: 9397: 9394: 9391: 9388: 9377: 9376: 9365: 9362: 9359: 9356: 9346: 9342: 9341: 9338: 9327: 9324: 9321: 9318: 9315: 9312: 9309: 9298: 9297: 9286: 9283: 9280: 9277: 9267: 9263: 9262: 9259: 9248: 9245: 9242: 9239: 9236: 9233: 9230: 9219: 9218: 9207: 9204: 9201: 9198: 9188: 9185: 9182: 9181: 9178: 9177: 9174: 9170: 9169: 9166: 9155: 9152: 9149: 9146: 9143: 9132: 9131: 9120: 9117: 9114: 9111: 9101: 9097: 9096: 9093: 9082: 9079: 9076: 9065: 9064: 9053: 9050: 9047: 9037: 9034: 9028: 9025: 9022: 9021: 9018: 9014: 9013: 9010: 8999: 8996: 8993: 8990: 8987: 8976: 8975: 8964: 8961: 8958: 8955: 8945: 8941: 8940: 8937: 8926: 8923: 8920: 8909: 8908: 8897: 8894: 8891: 8881: 8878: 8856: 8853: 8850: 8849: 8846: 8842: 8841: 8838: 8827: 8824: 8821: 8818: 8815: 8804: 8803: 8792: 8789: 8786: 8783: 8773: 8769: 8768: 8765: 8754: 8751: 8748: 8745: 8742: 8731: 8730: 8719: 8716: 8713: 8710: 8700: 8696: 8695: 8692: 8681: 8678: 8675: 8664: 8663: 8652: 8649: 8646: 8636: 8633: 8605: 8600: 8596: 8593: 8590: 8586: 8582: 8579: 8576: 8572: 8568: 8565: 8562: 8559: 8555: 8550: 8545: 8541: 8537: 8532: 8528: 8525: 8522: 8518: 8514: 8511: 8507: 8502: 8487: 8486: 8483: 8479: 8478: 8475: 8463: 8458: 8454: 8451: 8448: 8445: 8442: 8439: 8435: 8431: 8428: 8424: 8420: 8417: 8414: 8410: 8405: 8401: 8398: 8395: 8392: 8389: 8386: 8382: 8378: 8375: 8371: 8367: 8364: 8353: 8352: 8341: 8338: 8335: 8332: 8322: 8318: 8317: 8314: 8302: 8298: 8295: 8292: 8289: 8286: 8283: 8279: 8275: 8272: 8269: 8265: 8260: 8256: 8253: 8250: 8247: 8244: 8241: 8237: 8233: 8230: 8226: 8222: 8219: 8208: 8207: 8196: 8193: 8190: 8187: 8177: 8173: 8172: 8169: 8157: 8153: 8150: 8147: 8144: 8141: 8138: 8134: 8130: 8127: 8124: 8120: 8116: 8113: 8110: 8107: 8104: 8101: 8097: 8093: 8090: 8079: 8078: 8067: 8064: 8061: 8058: 8048: 8044: 8043: 8040: 8029: 8026: 8023: 8020: 8017: 8014: 8011: 8007: 8003: 8000: 7997: 7994: 7991: 7988: 7984: 7980: 7977: 7966: 7965: 7954: 7951: 7948: 7945: 7935: 7931: 7930: 7927: 7916: 7913: 7910: 7907: 7904: 7901: 7898: 7895: 7892: 7889: 7886: 7883: 7880: 7869: 7868: 7857: 7854: 7851: 7841: 7838: 7820: 7817: 7814: 7811: 7791: 7788: 7785: 7782: 7768: 7767: 7764: 7760: 7759: 7756: 7745: 7742: 7739: 7736: 7733: 7722: 7721: 7710: 7707: 7704: 7701: 7691: 7687: 7686: 7683: 7672: 7669: 7666: 7663: 7660: 7657: 7654: 7651: 7648: 7645: 7634: 7633: 7622: 7617: 7613: 7609: 7606: 7596: 7592: 7591: 7588: 7577: 7574: 7571: 7568: 7565: 7562: 7559: 7548: 7547: 7536: 7533: 7530: 7527: 7517: 7513: 7512: 7509: 7498: 7495: 7492: 7489: 7486: 7483: 7480: 7469: 7468: 7457: 7452: 7448: 7444: 7441: 7431: 7427: 7426: 7423: 7412: 7409: 7406: 7403: 7400: 7389: 7388: 7377: 7374: 7371: 7368: 7358: 7354: 7353: 7350: 7339: 7336: 7333: 7322: 7321: 7310: 7307: 7304: 7294: 7291: 7263: 7260: 7257: 7254: 7251: 7239: 7236: 7223: 7176: 7156: 7136: 7113: 7110: 7107: 7087: 7067: 7047: 7027: 7007: 6987: 6967: 6947: 6927: 6907: 6887: 6884: 6881: 6861: 6858: 6854: 6850: 6826: 6823: 6819: 6815: 6812: 6809: 6789: 6786: 6782: 6778: 6775: 6772: 6752: 6748: 6744: 6724: 6721: 6717: 6713: 6690: 6686: 6665: 6645: 6625: 6605: 6585: 6565: 6545: 6542: 6538: 6534: 6514: 6511: 6508: 6488: 6468: 6448: 6428: 6423: 6419: 6414: 6410: 6387: 6364: 6361: 6347: 6327: 6324: 6320: 6316: 6296: 6293: 6289: 6285: 6271: 6270: 6259: 6254: 6251: 6246: 6235: 6231: 6227: 6224: 6221: 6218: 6215: 6210: 6206: 6202: 6199: 6185: 6181: 6177: 6174: 6171: 6168: 6165: 6160: 6156: 6152: 6149: 6131: 6120: 6115: 6112: 6107: 6098: 6095: 6090: 6086: 6082: 6079: 6076: 6073: 6070: 6065: 6061: 6048: 6045: 6040: 6036: 6032: 6029: 6026: 6023: 6020: 6015: 6011: 5991: 5990: 5979: 5974: 5971: 5966: 5957: 5954: 5951: 5948: 5945: 5933: 5930: 5927: 5924: 5921: 5918: 5915: 5897: 5886: 5881: 5878: 5873: 5864: 5861: 5858: 5855: 5852: 5840: 5837: 5834: 5831: 5828: 5825: 5822: 5803: 5802: 5791: 5786: 5783: 5778: 5769: 5766: 5763: 5760: 5757: 5745: 5742: 5739: 5721: 5710: 5705: 5702: 5697: 5688: 5685: 5682: 5679: 5676: 5664: 5661: 5658: 5639: 5638: 5635: 5627: 5626: 5615: 5612: 5608: 5604: 5595: 5592: 5589: 5586: 5583: 5580: 5577: 5565: 5562: 5559: 5556: 5552: 5548: 5545: 5542: 5539: 5536: 5518: 5507: 5504: 5500: 5496: 5487: 5484: 5481: 5478: 5475: 5472: 5469: 5457: 5454: 5451: 5448: 5444: 5440: 5437: 5434: 5431: 5428: 5409: 5408: 5397: 5394: 5390: 5386: 5377: 5374: 5371: 5368: 5365: 5362: 5359: 5347: 5344: 5341: 5338: 5334: 5330: 5327: 5324: 5321: 5318: 5300: 5289: 5286: 5282: 5278: 5269: 5266: 5263: 5260: 5257: 5254: 5251: 5239: 5236: 5233: 5230: 5226: 5222: 5219: 5216: 5213: 5210: 5191: 5190: 5179: 5176: 5172: 5168: 5159: 5156: 5153: 5150: 5147: 5144: 5132: 5129: 5126: 5123: 5120: 5102: 5091: 5088: 5084: 5080: 5071: 5068: 5065: 5062: 5059: 5056: 5044: 5041: 5038: 5035: 5032: 5013: 5012: 5001: 4998: 4994: 4990: 4981: 4978: 4975: 4972: 4969: 4966: 4963: 4951: 4948: 4945: 4942: 4939: 4936: 4933: 4915: 4904: 4901: 4897: 4893: 4884: 4881: 4878: 4875: 4872: 4869: 4866: 4863: 4860: 4857: 4854: 4842: 4839: 4836: 4833: 4830: 4826: 4823: 4820: 4817: 4814: 4795: 4794: 4783: 4780: 4776: 4772: 4763: 4760: 4757: 4754: 4751: 4748: 4745: 4733: 4730: 4727: 4724: 4721: 4717: 4714: 4711: 4708: 4705: 4687: 4676: 4673: 4669: 4665: 4656: 4653: 4650: 4647: 4644: 4641: 4638: 4626: 4623: 4620: 4617: 4614: 4610: 4607: 4604: 4601: 4598: 4579: 4578: 4567: 4562: 4558: 4553: 4549: 4540: 4537: 4534: 4531: 4528: 4525: 4522: 4510: 4507: 4504: 4501: 4498: 4480: 4469: 4464: 4460: 4455: 4451: 4442: 4439: 4436: 4433: 4430: 4427: 4424: 4412: 4409: 4406: 4403: 4400: 4381: 4380: 4369: 4364: 4360: 4355: 4351: 4342: 4339: 4336: 4333: 4330: 4327: 4324: 4312: 4309: 4306: 4303: 4300: 4282: 4271: 4266: 4262: 4257: 4253: 4244: 4241: 4238: 4235: 4232: 4229: 4226: 4214: 4211: 4208: 4205: 4202: 4183: 4182: 4179: 4171: 4170: 4159: 4154: 4151: 4148: 4143: 4134: 4131: 4128: 4125: 4122: 4119: 4116: 4104: 4101: 4098: 4095: 4092: 4088: 4085: 4082: 4079: 4076: 4058: 4047: 4044: 4041: 4032: 4029: 4026: 3997: 3996: 3993: 3984:quantification 3979: 3978: 3973:, and 'P' for 3954: 3934: 3931: 3911: 3908: 3888: 3885: 3865: 3862: 3842: 3839: 3819: 3816: 3806: 3794: 3791: 3787: 3783: 3780: 3777: 3757: 3737: 3717: 3697: 3677: 3657: 3637: 3617: 3614: 3610: 3606: 3603: 3600: 3590: 3578: 3558: 3543: 3531: 3511: 3501: 3489: 3479: 3478: 3477: 3461: 3446: 3430: 3399: 3379: 3376: 3373: 3370: 3367: 3357: 3345: 3325: 3315: 3291: 3276: 3273: 3260: 3257: 3245:Hilbert system 3236: 3233: 3207: 3206: 3195: 3192: 3189: 3186: 3183: 3180: 3177: 3165: 3164: 3148: 3145: 3142: 3139: 3136: 3124: 3121: 3118: 3115: 3112: 3109: 3092: 3089: 3079: 3063: 3060: 3057: 3054: 3051: 3039: 3036: 3033: 3030: 3027: 3024: 3007: 3004: 2993: 2992: 2976: 2973: 2970: 2967: 2964: 2961: 2958: 2946: 2943: 2940: 2937: 2934: 2931: 2928: 2911: 2908: 2898: 2882: 2879: 2876: 2873: 2870: 2866: 2863: 2860: 2857: 2854: 2842: 2839: 2836: 2833: 2830: 2827: 2824: 2808: 2805: 2794: 2793: 2777: 2774: 2771: 2768: 2765: 2762: 2759: 2747: 2744: 2741: 2738: 2735: 2732: 2729: 2712: 2709: 2699: 2683: 2680: 2677: 2674: 2671: 2667: 2664: 2661: 2658: 2655: 2643: 2640: 2637: 2634: 2631: 2628: 2625: 2609: 2606: 2595: 2594: 2578: 2575: 2572: 2569: 2566: 2562: 2559: 2556: 2553: 2550: 2538: 2535: 2532: 2529: 2526: 2523: 2520: 2504: 2501: 2491: 2475: 2472: 2469: 2466: 2463: 2460: 2457: 2445: 2442: 2439: 2436: 2433: 2430: 2427: 2410: 2407: 2396: 2395: 2392: 2383:inference line 2368:reduction tree 2360: 2359: 2348: 2345: 2342: 2339: 2336: 2333: 2330: 2316: 2315: 2304: 2301: 2298: 2295: 2292: 2289: 2286: 2276: 2265: 2262: 2259: 2256: 2253: 2250: 2247: 2244: 2221: 2218: 2215: 2212: 2192: 2189: 2186: 2175: 2174: 2163: 2160: 2157: 2154: 2151: 2148: 2145: 2142: 2139: 2129: 2118: 2115: 2112: 2109: 2106: 2103: 2100: 2097: 2094: 2076: 2075: 2064: 2061: 2058: 2055: 2052: 2049: 2046: 2043: 2040: 2037: 2034: 2031: 2028: 2025: 2022: 2019: 2016: 1998: 1997: 1986: 1983: 1980: 1977: 1974: 1971: 1968: 1965: 1962: 1959: 1956: 1953: 1950: 1947: 1944: 1941: 1938: 1935: 1932: 1918: 1917: 1906: 1903: 1900: 1897: 1894: 1891: 1888: 1885: 1882: 1879: 1876: 1873: 1870: 1867: 1864: 1861: 1858: 1855: 1852: 1834: 1833: 1822: 1819: 1816: 1813: 1810: 1807: 1804: 1801: 1798: 1795: 1792: 1789: 1786: 1783: 1780: 1777: 1774: 1771: 1768: 1765: 1762: 1759: 1756: 1753: 1730: 1716: 1715: 1704: 1701: 1698: 1695: 1692: 1689: 1686: 1683: 1680: 1677: 1674: 1671: 1668: 1665: 1662: 1659: 1656: 1653: 1650: 1647: 1644: 1641: 1638: 1612: 1609: 1599: 1596: 1586: 1583: 1572: 1569: 1553: 1552: 1551: 1550: 1539: 1534: 1530: 1526: 1523: 1520: 1517: 1512: 1508: 1504: 1501: 1496: 1492: 1488: 1485: 1480: 1476: 1472: 1469: 1466: 1461: 1457: 1453: 1448: 1444: 1440: 1437: 1434: 1417: 1416: 1415: 1414: 1401: 1397: 1393: 1390: 1387: 1382: 1378: 1374: 1369: 1365: 1361: 1356: 1352: 1348: 1345: 1342: 1339: 1334: 1330: 1326: 1323: 1318: 1314: 1310: 1307: 1283: 1282: 1271: 1266: 1262: 1258: 1255: 1252: 1247: 1243: 1239: 1236: 1233: 1228: 1224: 1220: 1217: 1214: 1209: 1205: 1201: 1198: 1184: 1183: 1170: 1166: 1162: 1159: 1156: 1151: 1147: 1143: 1138: 1134: 1130: 1127: 1124: 1119: 1115: 1088: 1084: 1058: 1054: 1027: 1024: 1004: 984: 964: 942: 938: 915: 911: 875: 874: 863: 858: 854: 850: 847: 844: 839: 835: 831: 826: 822: 818: 815: 812: 807: 803: 787: 784: 780: 779: 768: 765: 762: 757: 753: 749: 746: 743: 738: 734: 730: 727: 713: 712: 701: 698: 693: 689: 685: 682: 679: 674: 670: 646: 624: 620: 597: 593: 567: 563: 542: 539: 519: 497: 493: 472: 444: 441: 438: 418: 396: 392: 380: 379: 368: 365: 360: 356: 352: 349: 346: 341: 337: 333: 328: 324: 305:Main article: 302: 299: 259: 248: 247: 236: 206:Hilbert system 204:Main article: 201: 198: 174:meta-theoretic 162:intuitionistic 138:formal systems 125: 122: 118:free variables 101: 100: 99: 98: 95: 86: 76:proof calculus 15: 9: 6: 4: 3: 2: 13415: 13404: 13401: 13399: 13396: 13394: 13391: 13390: 13388: 13374: 13364: 13361: 13359: 13356: 13354: 13351: 13349: 13346: 13344: 13341: 13339: 13336: 13334: 13331: 13329: 13326: 13324: 13321: 13319: 13316: 13315: 13312: 13303: 13298: 13296: 13291: 13289: 13284: 13283: 13280: 13274: 13271: 13269: 13266: 13262: 13258: 13257: 13252: 13248: 13246: 13242: 13239: 13238: 13228: 13222: 13218: 13214: 13210: 13206: 13200: 13196: 13192: 13188: 13184: 13178: 13174: 13170: 13166: 13165:Zach, Richard 13161: 13157: 13155:0-17-712040-1 13151: 13147: 13143: 13139: 13135: 13129: 13125: 13121: 13117: 13113: 13107: 13103: 13099: 13095: 13091: 13085: 13081: 13077: 13076:Bernays, Paul 13073: 13069: 13065: 13063:0-521-37181-3 13059: 13054: 13053: 13047: 13043: 13039: 13035: 13031: 13027: 13023: 13019: 13015: 13011: 13007: 13003: 12999: 12995: 12991: 12987: 12983: 12982: 12977: 12973: 12969: 12965: 12959: 12955: 12951: 12947: 12943: 12941:0-444-89840-9 12937: 12933: 12932: 12927: 12923: 12922: 12910: 12904: 12897: 12893: 12889: 12885: 12881: 12877: 12873: 12869: 12865: 12861: 12857: 12853: 12849: 12844: 12837: 12832: 12826:, p. 107 12825: 12824:Smullyan 1995 12820: 12813: 12807: 12800: 12794: 12786: 12779: 12772: 12766: 12762: 12761:Philip Wadler 12758: 12754: 12750: 12744: 12737: 12732: 12730: 12728: 12720: 12715: 12708: 12703: 12696: 12691: 12684: 12679: 12675: 12670: 12663: 12659: 12654: 12647: 12642: 12635: 12631: 12630:Smullyan 1995 12627: 12623: 12619: 12615: 12609: 12595: 12591: 12584: 12580: 12577:; Owre, Sam; 12576: 12570: 12561: 12554: 12550: 12546: 12541: 12534: 12530: 12525: 12518: 12513: 12506: 12505:Smullyan 1995 12501: 12494: 12489: 12482: 12477: 12470: 12465: 12458: 12453: 12451: 12443: 12438: 12436: 12428: 12424: 12419: 12417: 12412: 12402: 12399: 12397: 12394: 12392: 12389: 12387: 12384: 12383: 12377: 12360: 12352: 12349: 12343: 12340: 12331: 12316: 12313: 12307: 12303: 12299: 12293: 12290: 12272: 12271: 12270: 12256: 12228: 12225: 12219: 12213: 12207: 12192: 12189: 12186: 12183: 12180: 12177: 12159: 12158: 12157: 12140: 12109: 12078: 12050: 12022: 11993: 11976: 11974: 11952: 11948: 11935: 11932: 11929: 11926: 11923: 11920: 11905: 11902: 11899: 11896: 11889: 11886: 11883: 11880: 11862: 11861: 11860: 11843: 11839: 11827: 11817: 11815: 11811: 11807: 11803: 11797: 11787: 11764: 11750: 11693: 11687: 11660: 11659: 11658: 11635: 11608: 11607: 11606: 11604: 11601:representing 11600: 11570: 11568: 11549: 11538: 11532: 11529: 11526: 11523: 11520: 11514: 11496: 11493: 11490: 11480: 11477: 11474: 11456: 11455: 11454: 11437: 11433: 11420: 11403: 11400: 11397: 11394: 11391: 11380: 11375: 11373: 11368: 11360: 11352: 11350: 11346: 11341: 11327: 11324: 11313: 11295: 11292: 11259: 11243: 11235: 11231: 11221: 11219: 11214: 11212: 11208: 11203: 11199: 11191: 11189: 11179: 11176: 11165: 11162: 11161: 11157: 11142: 11137: 11133: 11123: 11119: 11113: 11109: 11105: 11096: 11092: 11087: 11082: 11074: 11069: 11065: 11062: 11059: 11055: 11048: 11044: 11039: 11035: 11027: 11009: 10993: 10992: 10988: 10973: 10969: 10959: 10955: 10949: 10945: 10941: 10932: 10928: 10923: 10918: 10914: 10910: 10905: 10901: 10898: 10895: 10891: 10884: 10880: 10871: 10853: 10837: 10836: 10832: 10818: 10812: 10808: 10804: 10798: 10794: 10790: 10781: 10777: 10772: 10768: 10764: 10759: 10755: 10752: 10749: 10745: 10738: 10734: 10725: 10707: 10704: 10691: 10690: 10686: 10672: 10666: 10662: 10657: 10653: 10650: 10647: 10643: 10636: 10632: 10628: 10624: 10620: 10614: 10610: 10606: 10597: 10593: 10588: 10579: 10561: 10558: 10545: 10544: 10540: 10526: 10520: 10517: 10511: 10507: 10502: 10498: 10495: 10492: 10488: 10481: 10477: 10473: 10469: 10465: 10459: 10455: 10451: 10442: 10438: 10433: 10424: 10406: 10390: 10379: 10376: 10375: 10371: 10357: 10351: 10347: 10343: 10340: 10337: 10333: 10329: 10325: 10321: 10315: 10311: 10307: 10298: 10294: 10289: 10280: 10262: 10259: 10246: 10245: 10241: 10227: 10221: 10217: 10213: 10207: 10203: 10199: 10190: 10186: 10181: 10177: 10173: 10169: 10166: 10163: 10159: 10150: 10132: 10129: 10116: 10115: 10111: 10097: 10091: 10087: 10083: 10077: 10073: 10069: 10060: 10056: 10051: 10047: 10043: 10039: 10033: 10029: 10025: 10016: 10012: 10007: 10003: 9999: 9995: 9992: 9989: 9985: 9976: 9956: 9952: 9948: 9935: 9934: 9930: 9916: 9910: 9907: 9901: 9897: 9893: 9887: 9883: 9879: 9870: 9866: 9861: 9857: 9853: 9849: 9846: 9843: 9839: 9830: 9812: 9809: 9796: 9795: 9791: 9777: 9771: 9767: 9763: 9757: 9753: 9749: 9740: 9736: 9731: 9727: 9724: 9718: 9714: 9710: 9707: 9704: 9700: 9691: 9671: 9667: 9663: 9650: 9649: 9645: 9631: 9625: 9621: 9617: 9608: 9604: 9600: 9597: 9591: 9587: 9583: 9580: 9577: 9573: 9564: 9546: 9530: 9519: 9516: 9515: 9511: 9497: 9491: 9488: 9477: 9459: 9446: 9443: 9442: 9437:   9436: 9429: 9426: 9425: 9421: 9407: 9404: 9401: 9395: 9392: 9389: 9386: 9378: 9360: 9344: 9343: 9339: 9325: 9322: 9319: 9316: 9313: 9310: 9307: 9299: 9281: 9278: 9265: 9264: 9260: 9246: 9243: 9240: 9237: 9234: 9231: 9228: 9220: 9202: 9199: 9186: 9175: 9172: 9171: 9167: 9153: 9150: 9147: 9144: 9141: 9133: 9115: 9112: 9099: 9098: 9094: 9080: 9077: 9074: 9066: 9048: 9035: 9033: 9032: 9027:   9026: 9019: 9016: 9015: 9011: 8997: 8994: 8991: 8988: 8985: 8977: 8959: 8956: 8943: 8942: 8938: 8924: 8921: 8918: 8910: 8892: 8879: 8877: 8876: 8872: 8869: 8868: 8864: 8861: 8860: 8855:   8854: 8847: 8844: 8843: 8839: 8825: 8819: 8816: 8813: 8805: 8787: 8784: 8771: 8770: 8766: 8752: 8749: 8746: 8740: 8732: 8714: 8698: 8697: 8693: 8679: 8676: 8673: 8665: 8647: 8634: 8631: 8630: 8626: 8623: 8622: 8619: 8603: 8598: 8594: 8584: 8580: 8574: 8570: 8566: 8557: 8553: 8548: 8543: 8535: 8530: 8526: 8523: 8520: 8516: 8509: 8505: 8500: 8484: 8481: 8480: 8476: 8461: 8456: 8449: 8446: 8443: 8437: 8433: 8429: 8422: 8418: 8412: 8408: 8403: 8396: 8393: 8390: 8384: 8380: 8376: 8369: 8365: 8354: 8336: 8320: 8319: 8315: 8300: 8293: 8290: 8287: 8281: 8277: 8273: 8267: 8263: 8258: 8251: 8248: 8245: 8239: 8235: 8231: 8224: 8220: 8209: 8191: 8175: 8174: 8170: 8155: 8148: 8145: 8142: 8136: 8132: 8128: 8122: 8118: 8111: 8108: 8105: 8099: 8095: 8091: 8080: 8062: 8046: 8045: 8041: 8024: 8021: 8018: 8012: 8009: 8005: 7998: 7995: 7992: 7986: 7982: 7978: 7967: 7949: 7933: 7932: 7928: 7911: 7908: 7905: 7899: 7896: 7890: 7887: 7884: 7878: 7870: 7852: 7839: 7836: 7835: 7832: 7815: 7786: 7765: 7762: 7761: 7757: 7743: 7737: 7734: 7731: 7723: 7705: 7702: 7689: 7688: 7684: 7670: 7664: 7661: 7658: 7655: 7649: 7646: 7643: 7635: 7615: 7611: 7607: 7594: 7593: 7589: 7575: 7569: 7566: 7563: 7560: 7557: 7549: 7531: 7528: 7515: 7514: 7510: 7496: 7493: 7490: 7484: 7481: 7478: 7470: 7450: 7446: 7442: 7429: 7428: 7424: 7410: 7407: 7404: 7398: 7390: 7372: 7356: 7355: 7351: 7337: 7334: 7331: 7323: 7305: 7292: 7289: 7288: 7285: 7283: 7279: 7278: 7261: 7255: 7252: 7249: 7235: 7221: 7212: 7210: 7206: 7200: 7198: 7194: 7190: 7174: 7154: 7134: 7125: 7111: 7108: 7105: 7085: 7065: 6985: 6945: 6885: 6882: 6879: 6856: 6852: 6838: 6821: 6817: 6813: 6807: 6784: 6780: 6776: 6770: 6750: 6746: 6719: 6702: 6688: 6663: 6583: 6540: 6512: 6509: 6506: 6466: 6421: 6417: 6412: 6399: 6385: 6378: 6374: 6370: 6360: 6359: 6345: 6322: 6291: 6233: 6225: 6222: 6219: 6216: 6213: 6208: 6200: 6183: 6175: 6172: 6169: 6166: 6163: 6158: 6150: 6132: 6093: 6088: 6080: 6077: 6074: 6071: 6068: 6063: 6043: 6038: 6030: 6027: 6024: 6021: 6018: 6013: 5993: 5992: 5952: 5949: 5946: 5928: 5925: 5922: 5919: 5916: 5898: 5859: 5856: 5853: 5835: 5832: 5829: 5826: 5823: 5805: 5804: 5764: 5761: 5758: 5740: 5722: 5683: 5680: 5677: 5659: 5641: 5640: 5636: 5633: 5632: 5610: 5590: 5587: 5584: 5578: 5560: 5554: 5550: 5546: 5540: 5537: 5519: 5502: 5482: 5479: 5476: 5470: 5452: 5446: 5442: 5438: 5432: 5429: 5411: 5410: 5392: 5372: 5369: 5366: 5360: 5342: 5336: 5332: 5328: 5322: 5319: 5301: 5284: 5264: 5261: 5258: 5252: 5234: 5228: 5224: 5220: 5214: 5211: 5193: 5192: 5174: 5154: 5151: 5145: 5127: 5124: 5121: 5103: 5086: 5066: 5063: 5057: 5039: 5036: 5033: 5015: 5014: 4996: 4976: 4973: 4967: 4964: 4946: 4943: 4940: 4937: 4934: 4916: 4899: 4879: 4873: 4870: 4864: 4861: 4855: 4837: 4834: 4831: 4821: 4818: 4815: 4797: 4796: 4778: 4774: 4758: 4755: 4752: 4749: 4746: 4728: 4725: 4722: 4712: 4709: 4706: 4688: 4671: 4667: 4651: 4648: 4645: 4642: 4639: 4621: 4618: 4615: 4605: 4602: 4599: 4581: 4580: 4560: 4556: 4551: 4535: 4532: 4529: 4526: 4523: 4505: 4502: 4499: 4481: 4462: 4458: 4453: 4437: 4434: 4431: 4428: 4425: 4407: 4404: 4401: 4383: 4382: 4362: 4358: 4353: 4337: 4334: 4331: 4328: 4325: 4307: 4304: 4301: 4283: 4264: 4260: 4255: 4239: 4236: 4233: 4230: 4227: 4209: 4206: 4203: 4185: 4184: 4180: 4177: 4176: 4129: 4123: 4117: 4099: 4093: 4090: 4086: 4083: 4077: 4059: 4042: 4030: 4027: 4024: 3999: 3998: 3994: 3991: 3990: 3987: 3985: 3976: 3972: 3968: 3952: 3932: 3929: 3909: 3906: 3886: 3883: 3863: 3860: 3840: 3837: 3817: 3814: 3807: 3789: 3785: 3781: 3775: 3755: 3735: 3715: 3695: 3675: 3655: 3635: 3612: 3608: 3604: 3598: 3591: 3548: 3544: 3529: 3509: 3502: 3487: 3480: 3475: 3474:disjunctively 3459: 3451: 3448:while on the 3447: 3444: 3443:conjunctively 3428: 3420: 3416: 3415: 3413: 3374: 3368: 3358: 3343: 3323: 3316: 3313: 3309: 3305: 3302:known as the 3289: 3282: 3281: 3280: 3272: 3270: 3266: 3259:The system LK 3256: 3254: 3250: 3246: 3242: 3232: 3230: 3226: 3220: 3217: 3215: 3193: 3190: 3184: 3181: 3178: 3166: 3143: 3140: 3137: 3122: 3116: 3110: 3087: 3080: 3061: 3058: 3052: 3034: 3031: 3025: 3002: 2995: 2994: 2974: 2971: 2965: 2962: 2959: 2944: 2938: 2935: 2929: 2906: 2899: 2877: 2874: 2871: 2864: 2861: 2855: 2837: 2834: 2828: 2825: 2803: 2796: 2795: 2775: 2772: 2769: 2766: 2760: 2745: 2742: 2739: 2736: 2730: 2710: 2707: 2700: 2678: 2675: 2672: 2662: 2659: 2656: 2638: 2635: 2632: 2629: 2626: 2607: 2604: 2597: 2596: 2576: 2573: 2567: 2560: 2557: 2551: 2536: 2533: 2530: 2527: 2521: 2502: 2499: 2492: 2470: 2467: 2464: 2461: 2458: 2440: 2437: 2434: 2431: 2428: 2408: 2405: 2398: 2397: 2393: 2390: 2389: 2386: 2384: 2379: 2375: 2371: 2369: 2365: 2346: 2343: 2340: 2337: 2334: 2331: 2328: 2321: 2320: 2319: 2302: 2299: 2296: 2293: 2290: 2287: 2284: 2277: 2263: 2260: 2257: 2254: 2251: 2248: 2245: 2235: 2234: 2233: 2219: 2216: 2213: 2190: 2184: 2161: 2158: 2155: 2152: 2149: 2146: 2143: 2137: 2130: 2116: 2113: 2110: 2107: 2104: 2101: 2098: 2092: 2085: 2084: 2083: 2081: 2062: 2059: 2056: 2053: 2050: 2047: 2041: 2035: 2029: 2023: 2017: 2007: 2006: 2005: 2003: 1984: 1981: 1975: 1972: 1969: 1963: 1957: 1951: 1945: 1939: 1933: 1923: 1922: 1921: 1904: 1895: 1892: 1889: 1883: 1877: 1871: 1865: 1859: 1853: 1843: 1842: 1841: 1839: 1817: 1808: 1805: 1802: 1784: 1778: 1772: 1766: 1760: 1751: 1744: 1743: 1742: 1728: 1721: 1699: 1690: 1687: 1684: 1666: 1660: 1654: 1648: 1642: 1629: 1628: 1627: 1624: 1622: 1618: 1604: 1595: 1592: 1582: 1579: 1568: 1564: 1562: 1556: 1532: 1528: 1521: 1518: 1515: 1510: 1506: 1499: 1494: 1490: 1483: 1478: 1474: 1470: 1467: 1464: 1459: 1455: 1451: 1446: 1442: 1432: 1425: 1424: 1422: 1421: 1420: 1399: 1395: 1391: 1388: 1385: 1380: 1376: 1372: 1367: 1363: 1359: 1354: 1350: 1343: 1340: 1337: 1332: 1328: 1321: 1316: 1312: 1305: 1298: 1297: 1296: 1295: 1294: 1292: 1286: 1264: 1260: 1256: 1253: 1250: 1245: 1241: 1226: 1222: 1218: 1215: 1212: 1207: 1203: 1196: 1189: 1188: 1187: 1168: 1164: 1160: 1157: 1154: 1149: 1145: 1141: 1136: 1132: 1128: 1125: 1122: 1117: 1113: 1105: 1104: 1103: 1086: 1082: 1074: 1056: 1052: 1044: 1039: 1025: 1022: 1002: 982: 962: 940: 936: 913: 909: 900: 896: 892: 888: 884: 880: 861: 856: 852: 848: 845: 842: 837: 833: 829: 824: 820: 816: 813: 810: 805: 801: 793: 792: 791: 783: 766: 755: 751: 747: 744: 741: 736: 732: 725: 718: 717: 716: 699: 696: 691: 687: 683: 680: 677: 672: 668: 660: 659: 658: 644: 622: 618: 595: 591: 581: 565: 561: 540: 537: 517: 495: 491: 470: 462: 458: 442: 439: 436: 416: 394: 390: 366: 363: 358: 354: 350: 347: 344: 339: 335: 331: 326: 322: 314: 313: 312: 308: 298: 296: 292: 287: 285: 281: 277: 273: 257: 234: 227: 226: 225: 223: 219: 215: 214: 207: 197: 195: 191: 187: 183: 179: 175: 171: 167: 163: 159: 155: 151: 147: 143: 139: 135: 131: 121: 119: 115: 111: 105: 96: 93: 90: 89: 87: 84: 83:Hilbert style 81: 80: 79: 77: 72: 70: 66: 62: 58: 54: 50: 46: 42: 38: 34: 30: 29:argumentation 26: 22: 13393:Proof theory 13357: 13333:Karnaugh map 13318:Venn diagram 13254: 13216: 13194: 13168: 13145: 13123: 13101: 13079: 13051: 13021: 13017: 12985: 12979: 12953: 12930: 12908: 12903: 12895: 12891: 12887: 12883: 12879: 12875: 12871: 12867: 12863: 12859: 12855: 12851: 12848:Gentzen 1934 12843: 12831: 12819: 12806: 12798: 12793: 12784: 12771: 12743: 12714: 12707:Gentzen 1934 12702: 12695:Gentzen 1934 12690: 12682: 12677: 12674:Gentzen 1934 12669: 12661: 12658:Gentzen 1934 12653: 12648:, p. 10 12641: 12634:Gentzen 1934 12608: 12597:. Retrieved 12589: 12569: 12560: 12540: 12524: 12512: 12500: 12488: 12476: 12464: 12427:Gentzen 1935 12423:Gentzen 1934 12401:Proof theory 12375: 12248: 11977: 11970: 11823: 11805: 11799: 11716: 11656: 11602: 11576: 11567:linear logic 11564: 11421: 11376: 11369: 11366: 11358: 11348: 11342: 11314:the sequent 11258:semantically 11227: 11215: 11204: 11200: 11197: 11185: 11171: 8490: 7771: 7281: 7275: 7241: 7213: 7201: 7196: 7126: 6839: 6703: 6616:, then from 6400: 6372: 6368: 6366: 6275: 6274: 3980: 3974: 3970: 3966: 3473: 3449: 3442: 3418: 3417:when on the 3314:on the right 3312:propositions 3311: 3307: 3278: 3264: 3262: 3253:modus ponens 3238: 3221: 3218: 3213: 3210: 2382: 2380: 2376: 2372: 2367: 2361: 2317: 2176: 2077: 1999: 1919: 1835: 1717: 1625: 1614: 1588: 1574: 1565: 1557: 1554: 1418: 1287: 1284: 1185: 1073:at least one 1072: 1042: 1040: 898: 894: 890: 886: 882: 876: 789: 781: 714: 582: 456: 381: 310: 288: 275: 249: 217: 211: 209: 189: 165: 145: 141: 130:proof theory 127: 106: 102: 73: 57:formal logic 24: 18: 13353:Truth table 12856:klassischer 12836:Kleene 2002 12753:implication 12719:Kleene 2002 12622:Kleene 2009 12618:Kleene 2002 12553:Suppes 1999 12545:Lemmon 1965 12529:Suppes 1999 12493:Kleene 2002 12481:Kleene 2009 12457:Kleene 2009 7284:in Latin). 3986:are added. 3975:Permutation 3971:Contraction 3668:in formula 3308:assumptions 3249:shown below 3095:rule:  3010:rule:  2914:rule:  2811:rule:  2715:rule:  2612:rule:  2507:rule:  2413:rule:  2378:arguments. 2364:rooted tree 2080:disjunction 2002:conjunction 1838:implication 284:modal logic 178:consistency 110:quantifiers 13387:Categories 12919:References 12757:hypothesis 12614:Curry 1977 12599:2015-05-29 12590:User guide 12517:Curry 1977 12469:Curry 1977 12442:Curry 1977 12249:and (when 11379:admissible 6373:structural 3982:regarding 3969:, 'C' for 3214:decomposed 891:consequent 883:antecedent 530:such that 382:where the 39:(called a 13261:EMS Press 13215:(1999) . 13193:(1995) . 13122:(2002) . 13100:(2009) . 13078:(1970) . 13038:186239837 13002:121546341 12952:(1977) . 12880:classical 12646:Buss 1998 12551:based on 12350:∨ 12338:∀ 12332:⊢ 12329:Γ 12314:∨ 12291:⊢ 12288:Γ 12226:∨ 12217:→ 12208:⊢ 12205:Γ 12190:∨ 12184:⊢ 12175:Γ 12137:∀ 12106:→ 12075:∀ 12047:→ 12020:¬ 11990:→ 11949:∨ 11933:⊢ 11927:∨ 11918:Γ 11903:⊢ 11894:Γ 11887:⊢ 11878:Γ 11840:∨ 11771:⊥ 11768:→ 11758:⟺ 11748:¬ 11725:⊥ 11697:Δ 11694:⊢ 11691:⊥ 11685:Γ 11636:⊢ 11633:⊥ 11585:⊥ 11573:Absurdity 11542:Π 11536:Δ 11533:⊢ 11527:∨ 11518:Σ 11512:Γ 11500:Π 11497:⊢ 11488:Σ 11484:Δ 11481:⊢ 11472:Γ 11434:∨ 11407:Δ 11398:⊢ 11389:Γ 11372:multisets 11349:Hauptsatz 11325:⊢ 11322:Γ 11293:⊨ 11290:Γ 11268:Γ 11207:sequences 11175:multisets 11131:¬ 11128:→ 11117:¬ 11114:∧ 11103:¬ 11100:→ 11079:→ 11063:∨ 11052:→ 11036:⊢ 11007:→ 10967:¬ 10964:→ 10953:¬ 10950:∧ 10939:¬ 10936:→ 10915:⊢ 10899:∨ 10888:→ 10851:→ 10816:¬ 10813:⊢ 10802:¬ 10799:∧ 10788:¬ 10785:→ 10753:∨ 10742:→ 10670:¬ 10667:⊢ 10651:∨ 10640:→ 10618:¬ 10615:∧ 10604:¬ 10601:→ 10524:¬ 10515:¬ 10512:⊢ 10496:∨ 10485:→ 10463:¬ 10460:∧ 10449:¬ 10446:→ 10404:→ 10355:¬ 10352:⊢ 10341:∨ 10319:¬ 10316:∧ 10305:¬ 10302:→ 10225:¬ 10222:⊢ 10211:¬ 10208:∧ 10197:¬ 10194:→ 10167:∨ 10095:¬ 10092:⊢ 10081:¬ 10078:∧ 10067:¬ 10064:→ 10037:¬ 10034:∧ 10023:¬ 10020:→ 9993:∨ 9949:∧ 9914:¬ 9911:⊢ 9905:¬ 9891:¬ 9888:∧ 9877:¬ 9874:→ 9847:∨ 9775:¬ 9772:⊢ 9761:¬ 9758:∧ 9747:¬ 9744:→ 9722:¬ 9708:∨ 9664:∧ 9629:¬ 9626:⊢ 9615:¬ 9612:→ 9595:¬ 9581:∨ 9544:→ 9495:¬ 9492:⊢ 9486:¬ 9405:⊢ 9399:¬ 9390:∨ 9358:¬ 9317:⊢ 9311:∨ 9238:⊢ 9232:∨ 9200:∨ 9145:⊢ 9078:⊢ 8989:⊢ 8922:⊢ 8823:¬ 8814:⊢ 8744:¬ 8741:⊢ 8712:¬ 8677:⊢ 8592:¬ 8589:→ 8578:¬ 8575:∧ 8564:¬ 8561:→ 8540:→ 8524:∨ 8513:→ 8427:∃ 8416:∀ 8413:⊢ 8374:∀ 8363:∃ 8334:∀ 8271:∃ 8268:⊢ 8229:∀ 8218:∃ 8189:∃ 8126:∃ 8123:⊢ 8089:∀ 8060:∃ 8010:⊢ 7976:∀ 7947:∀ 7897:⊢ 7813:∃ 7784:∀ 7741:¬ 7738:∨ 7732:⊢ 7668:¬ 7665:∨ 7653:¬ 7650:∨ 7644:⊢ 7608:∨ 7573:¬ 7570:∨ 7558:⊢ 7488:¬ 7485:∨ 7479:⊢ 7443:∨ 7402:¬ 7399:⊢ 7370:¬ 7335:⊢ 7259:¬ 7256:∨ 7250:⊢ 7109:∧ 7046:Σ 7026:Γ 7006:Σ 6966:Γ 6926:Σ 6906:Γ 6883:∧ 6853:∧ 6743:∀ 6716:∀ 6685:¬ 6644:Δ 6624:Γ 6604:Δ 6564:Γ 6537:¬ 6510:∧ 6487:Δ 6447:Δ 6413:∧ 6386:⊢ 6377:turnstile 6319:∃ 6288:∀ 6230:Δ 6205:Δ 6201:⊢ 6198:Γ 6180:Δ 6155:Δ 6151:⊢ 6148:Γ 6097:Δ 6094:⊢ 6085:Γ 6060:Γ 6047:Δ 6044:⊢ 6035:Γ 6010:Γ 5956:Δ 5947:⊢ 5944:Γ 5932:Δ 5917:⊢ 5914:Γ 5863:Δ 5860:⊢ 5851:Γ 5839:Δ 5836:⊢ 5821:Γ 5768:Δ 5759:⊢ 5756:Γ 5744:Δ 5741:⊢ 5738:Γ 5687:Δ 5684:⊢ 5675:Γ 5663:Δ 5660:⊢ 5657:Γ 5607:∃ 5594:Δ 5582:∃ 5579:⊢ 5576:Γ 5564:Δ 5538:⊢ 5535:Γ 5499:∃ 5486:Δ 5483:⊢ 5474:∃ 5468:Γ 5456:Δ 5453:⊢ 5427:Γ 5389:∀ 5376:Δ 5364:∀ 5361:⊢ 5358:Γ 5346:Δ 5320:⊢ 5317:Γ 5281:∀ 5268:Δ 5265:⊢ 5256:∀ 5250:Γ 5238:Δ 5235:⊢ 5209:Γ 5171:¬ 5158:Δ 5149:¬ 5146:⊢ 5143:Γ 5131:Δ 5128:⊢ 5119:Γ 5083:¬ 5070:Δ 5067:⊢ 5061:¬ 5055:Γ 5043:Δ 5034:⊢ 5031:Γ 4993:→ 4980:Δ 4971:→ 4965:⊢ 4962:Γ 4950:Δ 4941:⊢ 4932:Γ 4896:→ 4883:Π 4877:Δ 4874:⊢ 4868:→ 4859:Σ 4853:Γ 4841:Π 4838:⊢ 4829:Σ 4825:Δ 4816:⊢ 4813:Γ 4775:∧ 4762:Δ 4753:∧ 4747:⊢ 4744:Γ 4732:Δ 4723:⊢ 4720:Γ 4716:Δ 4707:⊢ 4704:Γ 4668:∨ 4655:Δ 4652:⊢ 4646:∨ 4637:Γ 4625:Δ 4622:⊢ 4613:Γ 4609:Δ 4606:⊢ 4597:Γ 4552:∨ 4539:Δ 4530:∨ 4524:⊢ 4521:Γ 4509:Δ 4500:⊢ 4497:Γ 4454:∧ 4441:Δ 4438:⊢ 4432:∧ 4423:Γ 4411:Δ 4408:⊢ 4399:Γ 4354:∨ 4341:Δ 4332:∨ 4326:⊢ 4323:Γ 4311:Δ 4302:⊢ 4299:Γ 4256:∧ 4243:Δ 4240:⊢ 4234:∧ 4225:Γ 4213:Δ 4210:⊢ 4201:Γ 4133:Π 4127:Δ 4124:⊢ 4121:Σ 4115:Γ 4103:Π 4100:⊢ 4097:Σ 4081:Δ 4078:⊢ 4075:Γ 4028:⊢ 3953:⊢ 3577:∃ 3557:∀ 3460:⊢ 3429:⊢ 3398:Π 3378:Σ 3372:Δ 3366:Γ 3304:turnstile 3290:⊢ 3188:Δ 3185:⊢ 3176:Γ 3147:Δ 3144:⊢ 3135:Γ 3120:¬ 3114:Δ 3111:⊢ 3108:Γ 3091:¬ 3056:Δ 3053:⊢ 3050:Γ 3038:Δ 3035:⊢ 3029:¬ 3023:Γ 3006:¬ 2969:Δ 2966:⊢ 2957:Γ 2942:→ 2933:Δ 2930:⊢ 2927:Γ 2910:→ 2881:Δ 2878:⊢ 2869:Γ 2859:Δ 2856:⊢ 2853:Γ 2841:Δ 2838:⊢ 2832:→ 2823:Γ 2807:→ 2764:Δ 2761:⊢ 2758:Γ 2743:∨ 2734:Δ 2731:⊢ 2728:Γ 2711:∨ 2682:Δ 2679:⊢ 2670:Γ 2666:Δ 2663:⊢ 2654:Γ 2642:Δ 2639:⊢ 2633:∨ 2624:Γ 2608:∨ 2571:Δ 2568:⊢ 2565:Γ 2555:Δ 2552:⊢ 2549:Γ 2534:∧ 2525:Δ 2522:⊢ 2519:Γ 2503:∧ 2474:Δ 2471:⊢ 2456:Γ 2444:Δ 2441:⊢ 2435:∧ 2426:Γ 2409:∧ 2338:⊢ 2300:⊢ 2261:⊢ 2243:¬ 2217:∨ 2211:¬ 2188:→ 2159:⊢ 2141:→ 2114:⊢ 2096:→ 2060:⊢ 2039:→ 2030:∨ 2021:→ 1982:⊢ 1973:∧ 1955:→ 1946:∨ 1937:→ 1902:→ 1893:∧ 1884:⊢ 1875:→ 1866:∨ 1857:→ 1815:→ 1806:∧ 1794:→ 1782:→ 1773:∨ 1764:→ 1752:⊢ 1729:⊢ 1697:→ 1688:∧ 1676:→ 1664:→ 1655:∨ 1646:→ 1525:¬ 1522:∧ 1519:⋯ 1516:∧ 1503:¬ 1500:∧ 1487:¬ 1484:∧ 1471:∧ 1468:⋯ 1465:∧ 1452:∧ 1436:¬ 1433:⊢ 1392:∨ 1389:⋯ 1386:∨ 1373:∨ 1360:∨ 1347:¬ 1344:∨ 1341:⋯ 1338:∨ 1325:¬ 1322:∨ 1309:¬ 1306:⊢ 1257:∨ 1254:⋯ 1251:∨ 1235:→ 1219:∧ 1216:⋯ 1213:∧ 1197:⊢ 1158:… 1142:⊢ 1126:… 1071:is true, 1023:⊢ 901:. Again, 887:succedent 879:turnstile 846:… 830:⊢ 814:… 764:→ 748:∧ 745:⋯ 742:∧ 726:⊢ 697:⊢ 681:… 538:⊢ 471:⊢ 461:turnstile 440:≥ 364:⊢ 348:… 213:judgments 166:Hauptsatz 158:classical 49:inference 37:tautology 13167:(2021). 13144:(1965). 13012:(1935). 12974:(1934). 12549:System L 12533:System L 12380:See also 11355:Variants 11256:follows 11234:complete 7222:↚ 7197:cut-free 3229:complete 3168:Axiom: 899:sequents 463:symbol " 124:Overview 65:theorems 13263:, 2001 13243:in the 12156:become 11166:  11163:  11158:  10994:  10989:  10838:  10833:  10692:  10687:  10546:  10541:  10391:  10380:  10377:  10372:  10247:  10242:  10117:  10112:  9936:  9931:  9797:  9792:  9651:  9646:  9531:  9520:  9517:  9512:  9447:  9444:  9430:  9427:  9422:  9345:  9340:  9266:  9261:  9187:  9176:  9173:  9168:  9100:  9095:  9036:  9020:  9017:  9012:  8944:  8939:  8880:  8848:  8845:  8840:  8772:  8767:  8699:  8694:  8635:  8632:  8485:  8482:  8477:  8321:  8316:  8176:  8171:  8047:  8042:  7934:  7929:  7840:  7837:  7766:  7763:  7758:  7690:  7685:  7595:  7590:  7516:  7511:  7430:  7425:  7357:  7352:  7293:  7290:  7199:proof. 6369:logical 3452:of the 3421:of the 3271:below. 895:cedents 409:'s and 272:formula 270:is any 41:sequent 13223:  13201:  13179:  13152:  13130:  13108:  13086:  13060:  13036:  13000:  12960:  12938:  11597:, the 3992:Axiom 3390:, and 2394:Right 1591:Kleene 1423:or as 1015:where 250:where 61:axioms 13034:S2CID 12998:S2CID 12781:(PDF) 12749:prove 12586:(PDF) 12407:Notes 11717:With 11603:false 11230:sound 3450:right 3269:rules 3225:sound 2391:Left 1043:every 282:or a 67:in a 33:proof 13221:ISBN 13199:ISBN 13177:ISBN 13150:ISBN 13128:ISBN 13106:ISBN 13084:ISBN 13058:ISBN 12958:ISBN 12936:ISBN 12894:and 12886:and 12878:and 12870:und 12862:und 12854:und 12125:and 11812:and 11806:i.e. 11232:and 11211:sets 7802:and 7078:and 7038:and 6978:and 6918:and 6576:and 6371:and 6307:and 3995:Cut 3547:free 3522:and 3419:left 3336:and 3227:and 1186:and 975:and 928:and 715:and 457:list 276:e.g. 218:i.e. 160:and 156:(in 144:and 132:and 13026:doi 12990:doi 12759:."— 12751:an 6656:or 3728:in 3569:or 2203:as 897:or 889:or 152:in 128:In 43:by 19:In 13389:: 13259:, 13253:, 13171:. 13074:; 13032:. 13022:39 13020:. 13016:. 12996:. 12986:39 12984:. 12978:. 12896:NK 12892:NJ 12888:LK 12884:LJ 12872:NK 12868:NJ 12864:LK 12860:LJ 12763:, 12726:^ 12683:LK 12678:NK 12662:NJ 12592:. 12588:. 12449:^ 12434:^ 12425:, 12415:^ 12009:, 11975:. 11816:. 11786:. 11220:. 11213:. 11190:. 7831:. 7124:. 3922:, 3899:, 3876:, 3853:, 3830:, 3805:). 3265:LK 3216:. 2385:. 2370:. 1741:: 610:, 297:. 196:. 146:LJ 142:LK 23:, 13301:e 13294:t 13287:v 13229:. 13207:. 13185:. 13158:. 13136:. 13114:. 13092:. 13066:. 13040:. 13028:: 13004:. 12992:: 12966:. 12944:. 12602:. 12535:. 12429:. 12361:. 12353:C 12347:) 12344:A 12341:x 12335:( 12317:C 12311:] 12308:x 12304:/ 12300:y 12297:[ 12294:A 12257:y 12229:C 12223:) 12220:B 12214:A 12211:( 12193:C 12187:B 12181:A 12178:, 12144:) 12141:R 12133:( 12113:) 12110:R 12102:( 12082:) 12079:R 12071:( 12051:R 12026:) 12023:R 12017:( 11997:) 11994:R 11986:( 11956:) 11953:L 11945:( 11936:C 11930:B 11924:A 11921:, 11906:C 11900:B 11897:, 11890:C 11884:A 11881:, 11847:) 11844:L 11836:( 11774:) 11765:A 11762:( 11754:) 11751:A 11745:( 11688:, 11550:. 11539:, 11530:B 11524:A 11521:, 11515:, 11494:B 11491:, 11478:A 11475:, 11441:) 11438:L 11430:( 11404:, 11401:A 11395:A 11392:, 11328:A 11299:) 11296:A 11287:( 11244:A 11143:) 11138:) 11134:A 11124:) 11120:C 11110:) 11106:A 11097:B 11093:( 11088:( 11083:( 11075:) 11070:) 11066:C 11060:B 11056:( 11049:A 11045:( 11040:( 11013:) 11010:R 11004:( 10974:) 10970:A 10960:) 10956:C 10946:) 10942:A 10933:B 10929:( 10924:( 10919:( 10911:) 10906:) 10902:C 10896:B 10892:( 10885:A 10881:( 10857:) 10854:R 10848:( 10819:A 10809:) 10805:C 10795:) 10791:A 10782:B 10778:( 10773:( 10769:, 10765:) 10760:) 10756:C 10750:B 10746:( 10739:A 10735:( 10711:) 10708:L 10705:P 10702:( 10673:A 10663:) 10658:) 10654:C 10648:B 10644:( 10637:A 10633:( 10629:, 10625:) 10621:C 10611:) 10607:A 10598:B 10594:( 10589:( 10565:) 10562:R 10559:C 10556:( 10527:A 10521:, 10518:A 10508:) 10503:) 10499:C 10493:B 10489:( 10482:A 10478:( 10474:, 10470:) 10466:C 10456:) 10452:A 10443:B 10439:( 10434:( 10410:) 10407:L 10401:( 10358:A 10348:) 10344:C 10338:B 10334:( 10330:, 10326:) 10322:C 10312:) 10308:A 10299:B 10295:( 10290:( 10266:) 10263:L 10260:P 10257:( 10228:A 10218:) 10214:C 10204:) 10200:A 10191:B 10187:( 10182:( 10178:, 10174:) 10170:C 10164:B 10160:( 10136:) 10133:L 10130:C 10127:( 10098:A 10088:) 10084:C 10074:) 10070:A 10061:B 10057:( 10052:( 10048:, 10044:) 10040:C 10030:) 10026:A 10017:B 10013:( 10008:( 10004:, 10000:) 9996:C 9990:B 9986:( 9962:) 9957:2 9953:L 9946:( 9917:A 9908:C 9902:, 9898:) 9894:C 9884:) 9880:A 9871:B 9867:( 9862:( 9858:, 9854:) 9850:C 9844:B 9840:( 9816:) 9813:L 9810:P 9807:( 9778:A 9768:) 9764:C 9754:) 9750:A 9741:B 9737:( 9732:( 9728:, 9725:C 9719:, 9715:) 9711:C 9705:B 9701:( 9677:) 9672:1 9668:L 9661:( 9632:A 9622:) 9618:A 9609:B 9605:( 9601:, 9598:C 9592:, 9588:) 9584:C 9578:B 9574:( 9550:) 9547:L 9541:( 9498:A 9489:A 9463:) 9460:I 9457:( 9408:B 9402:C 9396:, 9393:C 9387:B 9364:) 9361:L 9355:( 9326:B 9323:, 9320:C 9314:C 9308:B 9285:) 9282:R 9279:P 9276:( 9247:C 9244:, 9241:B 9235:C 9229:B 9206:) 9203:L 9197:( 9154:C 9151:, 9148:B 9142:C 9119:) 9116:R 9113:W 9110:( 9081:C 9075:C 9052:) 9049:I 9046:( 8998:C 8995:, 8992:B 8986:B 8963:) 8960:R 8957:W 8954:( 8925:B 8919:B 8896:) 8893:I 8890:( 8826:A 8820:, 8817:A 8791:) 8788:R 8785:P 8782:( 8753:A 8750:, 8747:A 8718:) 8715:R 8709:( 8680:A 8674:A 8651:) 8648:I 8645:( 8604:) 8599:) 8595:A 8585:) 8581:C 8571:) 8567:A 8558:B 8554:( 8549:( 8544:( 8536:) 8531:) 8527:C 8521:B 8517:( 8510:A 8506:( 8501:( 8462:) 8457:) 8453:) 8450:y 8447:, 8444:x 8441:( 8438:p 8434:( 8430:y 8423:( 8419:x 8409:) 8404:) 8400:) 8397:y 8394:, 8391:x 8388:( 8385:p 8381:( 8377:x 8370:( 8366:y 8340:) 8337:R 8331:( 8301:) 8297:) 8294:y 8291:, 8288:x 8285:( 8282:p 8278:( 8274:y 8264:) 8259:) 8255:) 8252:y 8249:, 8246:x 8243:( 8240:p 8236:( 8232:x 8225:( 8221:y 8195:) 8192:L 8186:( 8156:) 8152:) 8149:y 8146:, 8143:x 8140:( 8137:p 8133:( 8129:y 8119:) 8115:) 8112:y 8109:, 8106:x 8103:( 8100:p 8096:( 8092:x 8066:) 8063:R 8057:( 8028:) 8025:y 8022:, 8019:x 8016:( 8013:p 8006:) 8002:) 7999:y 7996:, 7993:x 7990:( 7987:p 7983:( 7979:x 7953:) 7950:L 7944:( 7915:) 7912:y 7909:, 7906:x 7903:( 7900:p 7894:) 7891:y 7888:, 7885:x 7882:( 7879:p 7856:) 7853:I 7850:( 7819:) 7816:L 7810:( 7790:) 7787:R 7781:( 7744:A 7735:A 7709:) 7706:R 7703:C 7700:( 7671:A 7662:A 7659:, 7656:A 7647:A 7621:) 7616:1 7612:R 7605:( 7576:A 7567:A 7564:, 7561:A 7535:) 7532:R 7529:P 7526:( 7497:A 7494:, 7491:A 7482:A 7456:) 7451:2 7447:R 7440:( 7411:A 7408:, 7405:A 7376:) 7373:R 7367:( 7338:A 7332:A 7309:) 7306:I 7303:( 7280:( 7262:A 7253:A 7175:A 7155:A 7135:A 7112:B 7106:A 7086:B 7066:A 6986:B 6946:A 6886:B 6880:A 6860:) 6857:R 6849:( 6825:] 6822:x 6818:/ 6814:y 6811:[ 6808:A 6788:] 6785:x 6781:/ 6777:y 6774:[ 6771:A 6751:A 6747:x 6723:) 6720:R 6712:( 6689:A 6664:A 6584:A 6544:) 6541:R 6533:( 6513:B 6507:A 6467:A 6427:) 6422:1 6418:L 6409:( 6346:y 6326:) 6323:L 6315:( 6295:) 6292:R 6284:( 6258:) 6253:R 6250:P 6245:( 6234:2 6226:, 6223:A 6220:, 6217:B 6214:, 6209:1 6184:2 6176:, 6173:B 6170:, 6167:A 6164:, 6159:1 6119:) 6114:L 6111:P 6106:( 6089:2 6081:, 6078:A 6075:, 6072:B 6069:, 6064:1 6039:2 6031:, 6028:B 6025:, 6022:A 6019:, 6014:1 5978:) 5973:R 5970:C 5965:( 5953:, 5950:A 5929:, 5926:A 5923:, 5920:A 5885:) 5880:L 5877:C 5872:( 5857:A 5854:, 5833:A 5830:, 5827:A 5824:, 5790:) 5785:R 5782:W 5777:( 5765:, 5762:A 5709:) 5704:L 5701:W 5696:( 5681:A 5678:, 5614:) 5611:R 5603:( 5591:, 5588:A 5585:x 5561:, 5558:] 5555:x 5551:/ 5547:t 5544:[ 5541:A 5506:) 5503:L 5495:( 5480:A 5477:x 5471:, 5450:] 5447:x 5443:/ 5439:y 5436:[ 5433:A 5430:, 5396:) 5393:R 5385:( 5373:, 5370:A 5367:x 5343:, 5340:] 5337:x 5333:/ 5329:y 5326:[ 5323:A 5288:) 5285:L 5277:( 5262:A 5259:x 5253:, 5232:] 5229:x 5225:/ 5221:t 5218:[ 5215:A 5212:, 5178:) 5175:R 5167:( 5155:, 5152:A 5125:A 5122:, 5090:) 5087:L 5079:( 5064:A 5058:, 5040:, 5037:A 5000:) 4997:R 4989:( 4977:, 4974:B 4968:A 4947:, 4944:B 4938:A 4935:, 4903:) 4900:L 4892:( 4880:, 4871:B 4865:A 4862:, 4856:, 4835:B 4832:, 4822:, 4819:A 4782:) 4779:R 4771:( 4759:, 4756:B 4750:A 4729:, 4726:B 4713:, 4710:A 4675:) 4672:L 4664:( 4649:B 4643:A 4640:, 4619:B 4616:, 4603:A 4600:, 4566:) 4561:2 4557:R 4548:( 4536:, 4533:B 4527:A 4506:, 4503:B 4468:) 4463:2 4459:L 4450:( 4435:B 4429:A 4426:, 4405:B 4402:, 4368:) 4363:1 4359:R 4350:( 4338:, 4335:B 4329:A 4308:, 4305:A 4270:) 4265:1 4261:L 4252:( 4237:B 4231:A 4228:, 4207:A 4204:, 4158:) 4153:t 4150:u 4147:C 4142:( 4130:, 4118:, 4094:, 4091:A 4087:A 4084:, 4046:) 4043:I 4040:( 4031:A 4025:A 3977:. 3933:R 3930:P 3910:L 3907:P 3887:R 3884:C 3864:L 3861:C 3841:R 3838:W 3818:L 3815:W 3793:] 3790:x 3786:/ 3782:t 3779:[ 3776:A 3756:t 3736:A 3716:x 3696:t 3676:A 3656:x 3636:t 3616:] 3613:x 3609:/ 3605:t 3602:[ 3599:A 3589:. 3530:y 3510:x 3488:t 3375:, 3369:, 3344:B 3324:A 3194:A 3191:, 3182:A 3179:, 3141:A 3138:, 3123:A 3117:, 3088:R 3062:A 3059:, 3032:A 3026:, 3003:L 2975:B 2972:, 2963:A 2960:, 2945:B 2939:A 2936:, 2907:R 2875:B 2872:, 2865:A 2862:, 2835:B 2829:A 2826:, 2804:L 2776:B 2773:, 2770:A 2767:, 2746:B 2740:A 2737:, 2708:R 2676:B 2673:, 2660:A 2657:, 2636:B 2630:A 2627:, 2605:L 2577:B 2574:, 2561:A 2558:, 2537:B 2531:A 2528:, 2500:R 2468:B 2465:, 2462:A 2459:, 2438:B 2432:A 2429:, 2406:L 2347:r 2344:, 2341:p 2335:q 2332:, 2329:p 2303:r 2297:q 2294:, 2291:p 2288:, 2285:r 2264:r 2258:q 2255:, 2252:p 2249:, 2246:p 2220:r 2214:p 2191:r 2185:p 2162:r 2156:q 2153:, 2150:p 2147:, 2144:r 2138:q 2117:r 2111:q 2108:, 2105:p 2102:, 2099:r 2093:p 2063:r 2057:q 2054:, 2051:p 2048:, 2045:) 2042:r 2036:q 2033:( 2027:) 2024:r 2018:p 2015:( 1985:r 1979:) 1976:q 1970:p 1967:( 1964:, 1961:) 1958:r 1952:q 1949:( 1943:) 1940:r 1934:p 1931:( 1905:r 1899:) 1896:q 1890:p 1887:( 1881:) 1878:r 1872:q 1869:( 1863:) 1860:r 1854:p 1851:( 1821:) 1818:r 1812:) 1809:q 1803:p 1800:( 1797:( 1791:) 1788:) 1785:r 1779:q 1776:( 1770:) 1767:r 1761:p 1758:( 1755:( 1703:) 1700:r 1694:) 1691:q 1685:p 1682:( 1679:( 1673:) 1670:) 1667:r 1661:q 1658:( 1652:) 1649:r 1643:p 1640:( 1637:( 1538:) 1533:k 1529:B 1511:2 1507:B 1495:1 1491:B 1479:n 1475:A 1460:2 1456:A 1447:1 1443:A 1439:( 1400:k 1396:B 1381:2 1377:B 1368:1 1364:B 1355:n 1351:A 1333:2 1329:A 1317:1 1313:A 1270:) 1265:k 1261:B 1246:1 1242:B 1238:( 1232:) 1227:n 1223:A 1208:1 1204:A 1200:( 1169:k 1165:B 1161:, 1155:, 1150:1 1146:B 1137:n 1133:A 1129:, 1123:, 1118:1 1114:A 1087:i 1083:B 1057:i 1053:A 1026:B 1003:B 983:k 963:n 941:i 937:B 914:i 910:A 862:, 857:k 853:B 849:, 843:, 838:1 834:B 825:n 821:A 817:, 811:, 806:1 802:A 767:B 761:) 756:n 752:A 737:1 733:A 729:( 700:B 692:n 688:A 684:, 678:, 673:1 669:A 645:B 623:2 619:A 596:1 592:A 566:i 562:A 541:B 518:B 496:i 492:A 443:0 437:n 417:B 395:i 391:A 367:B 359:n 355:A 351:, 345:, 340:2 336:A 332:, 327:1 323:A 258:B 235:B

Index

mathematical logic
argumentation
proof
tautology
sequent
Gerhard Gentzen
inference
David Hilbert's
formal logic
axioms
theorems
first-order language
proof calculus
Hilbert style
Natural deduction
quantifiers
propositional calculus
free variables
proof theory
mathematical logic
formal systems
natural deduction
first-order logic
classical
intuitionistic
cut-elimination theorem
meta-theoretic
consistency
proof of the consistency of Peano arithmetic
Gödel's incompleteness theorems

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