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Zorn's lemma

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7049: 4195: 29: 4331:). Zorn's lemma can be expressed straightforwardly by observing that the set having no maximal element would be equivalent to stating that the set's ordering relation would be entire, which would allow us to apply the axiom of dependent choice to construct a countable chain. As a result, any partially ordered set with exclusively finite chains must have a maximal element. 184:
and the assumptions of the situation to get a contradiction. Zorn's lemma tidies up the conditions a situation needs to satisfy in order for such an argument to work and enables mathematicians to not have to repeat the transfinite induction argument by hand each time, but just check the conditions of
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More generally, strengthening the axiom of dependent choice to higher ordinals allows us to generalize the statement in the previous paragraph to higher cardinalities. In the limit where we allow arbitrarily large ordinals, we recover the proof of the full Zorn's lemma using the axiom of choice in
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The difference may seem subtle, but in many proofs that invoke Zorn's lemma one takes unions of some sort to produce an upper bound, and so the case of the empty chain may be overlooked; that is, the verification that all chains have upper bounds may have to deal with empty and non-empty chains
40:. The set of all sub-graphs that are trees is ordered by inclusion, and the union of a chain is an upper bound. Zorn's lemma says that a maximal tree must exist, which is a spanning tree since the graph is connected. Zorn's lemma is not needed for finite graphs, such as the one pictured here. 4156:
proved in 1922 a version of the lemma close to its modern formulation (it applies to sets ordered by inclusion and closed under unions of well-ordered chains). Essentially the same formulation (weakened by using arbitrary chains, not just well-ordered) was independently given by
2499:.) Note the above is a weak form of Zorn's lemma since Zorn's lemma says in particular that any set of subsets satisfying the above (1) and (2) has a maximal element. The point is that, conversely, Zorn's lemma follows from this weak form. Indeed, let 1016: 189:
If you are building a mathematical object in stages and find that (i) you have not finished even after infinitely many stages, and (ii) there seems to be nothing to stop you continuing to build, then Zorn’s lemma may well be able to help
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of set theory replacing the well-ordering theorem, exhibited some of its applications in algebra, and promised to show its equivalence with the axiom of choice in another paper, which never appeared.
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Indeed, trivially, Zorn's lemma implies the above lemma. Conversely, the above lemma implies the aforementioned weak form of Zorn's lemma, since a union gives a least upper bound.
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A proof that Zorn's lemma implies the axiom of choice illustrates a typical application of Zorn's lemma. (The structure of the proof is exactly the same as the one for the
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which states that every totally ordered subset of a given partially ordered set is contained in a maximal totally ordered subset of that partially ordered set.
2539:. Then it satisfies all of the above properties (it is nonempty since the empty subset is a chain.) Thus, by the above weak form, we find a maximal element 5428: 6103: 6186: 5327: 7736: 5029: 7719: 2025:), more than there are elements in any set (in other words, given any set of ordinals, there exists a larger ordinal), and the set 164:
without the axiom of choice) any one of the three is sufficient to prove the other two. An earlier formulation of Zorn's lemma is
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A weakened form of Zorn's lemma can be proven from ZF + DC (Zermelo–Fraenkel set theory with the axiom of choice replaced by the
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Moreover, Zorn's lemma (or one of its equivalent forms) implies some major results in other mathematical areas. For example,
4247:: "The Axiom of Choice is obviously true, the well-ordering principle obviously false, and who can tell about Zorn's lemma?" 5446: 1833: 7566: 6513: 5836: 4694: 4649: 4787:
from the weak form of Zorn's lemma. The meaning of passage there was unclear and so here we gave an alternative reasoning.
6518: 6508: 6245: 6098: 5451: 344:. The word "partial" is meant to indicate that not every pair of elements of a partially ordered set is required to be 5442: 7702: 7561: 6654: 5186: 5011: 5996: 7556: 6751: 6495: 5320: 180:
in some way, one can try proving the existence of such an object by assuming there is no maximal element and using
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The above proof can be formulated without explicitly referring to ordinals by considering the initial segments {
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contains a formal proof down to the finest detail of the equivalence of the axiom of choice and Zorn's Lemma.
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is assumed to be non-empty and satisfies the hypothesis that every non-empty chain has an upper bound in
2840:. Indeed, the existence of a maximal chain is exactly the assertion of the Hausdorff maximal principle. 2775: 7578: 7212: 7202: 7078: 6739: 6329: 5723: 5691: 5382: 3333: 2252:
The basic idea of the proof is to reduce the proof to proving the following weak form of Zorn's lemma:
1587: 1011:{\displaystyle a_{1}\mathbf {v} _{1}+a_{2}\mathbf {v} _{2}+\cdots +a_{k}\mathbf {v} _{k}=\mathbf {0} .} 3247: 7551: 7217: 7029: 6978: 6875: 6373: 6334: 5811: 5456: 4624: 4530:. Graduate Texts in Mathematics. Vol. 211 (Revised 3rd ed.). Springer-Verlag. p. 880. 4377: 4328: 4322: 75: 5485: 1911: 7769: 7483: 7110: 6870: 6800: 6339: 6191: 6174: 5897: 5377: 3381: 338: 4508: 2955: 7731: 7714: 6702: 6679: 6640: 6526: 6467: 6113: 6033: 5877: 5821: 5434: 4864: 4265: 4243:
A well-known joke alluding to this equivalency (which may defy human intuition) is attributed to
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Wolk, Elliot S. (1983), "On the principle of dependent choices and some forms of Zorn's lemma",
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To prove the existence of a mathematical object that can be viewed as a maximal element in some
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in 1935. It occurs in the proofs of several theorems of crucial importance, for instance the
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serves as an upper bound for the empty chain (that is, the empty subset viewed as a chain).
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contains an upper bound for the empty set and is thus not empty) and for any other ordinal
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NB: in the reference, this deduction is by noting there is an order-preserving embedding
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In this sense, Zorn's lemma is a powerful tool, applicable to many areas of mathematics.
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such that every totally ordered subset has an upper bound, and that for every element in
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The hypothesis of Zorn's lemma has been checked, and thus there is a maximal element in
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The hypothesis of Zorn's lemma has been checked, and thus there is a maximal element in
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which is used to prove one of the most fundamental results in functional analysis, the
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has an upper bound, and that upper bound has a bigger element. To actually define the
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This proof shows that actually a slightly stronger version of Zorn's lemma is true:
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will be exhausted before long and then we will run into the desired contradiction.
1799:. Suppose the lemma is false. Then there exists a partially ordered set, or poset, 604:), in fact the two formulations are equivalent: To verify this, suppose first that 600:
the additional condition of being non-empty, but obtains the same conclusion about
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of 1939 refers to a similar maximal principle as "le théorème de Zorn". The name "
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Variants of this formulation are sometimes used, such as requiring that the set
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contains at least one element, and that element contains at least 0, the union
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and that the "passage" allows to deduce the existence of a maximal element of
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The same proof also shows the following equivalent variant of Zorn's lemma:
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Although this formulation appears to be formally weaker (since it places on
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be a partially ordered set in which each chain has a least upper bound in
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there is another element bigger than it. For every totally ordered subset
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separately. So many authors prefer to verify the non-emptiness of the set
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Blass, Andreas (1984). "Existence of bases implies the Axiom of Choice".
4299: 1249: 1178: 624:; so the hypothesis implies that this subset must have an upper bound in 543: 486: 376:. An ordered set in which every pair of elements is comparable is called 68: 60: 28: 17: 806:
has an upper bound, that is, there exists a linearly independent subset
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Essentially the same proof also shows that Zorn's lemma implies the
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Zermelo's axiom of choice: Its origins, development & influence
4470:, ch. 2, §2 Some applications of the Axiom of Choice in mathematics 3946:. (Note this step does not need the axiom of choice.) The function 122: 4316: 1294:
is partially ordered by set inclusion. Finding a maximal ideal in
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has the property that every non-empty chain has an upper bound in
6615: 5407: 4602:. Universitext (Second ed.). Springer-Verlag. p. 164. 1760:, then it would contain 1, and that means one of the members of 1129:. This tells us there is a linearly dependent set of vectors in 7063: 4397: – Mathematical set containing a finite number of elements 2125:. Such sets can be easily characterized as well-ordered chains 748: 660:
rather than deal with the empty chain in the general argument.
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under the order relation, that is, in a partially ordered set
6159: 5505: 5350: 4571:. Universitext (2nd ed.). Springer-Verlag. p. 162. 4162: 2222:. That is, there is a maximal element which is comparable to 2199: 5132:"Zorn's Lemma | The Simpsons and their Mathematical Secrets" 4599:
An Invitation to General Algebra and Universal Constructions
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An Invitation to General Algebra and Universal Constructions
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A sketch of the proof of Zorn's lemma follows, assuming the
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then it contains 1; on the other hand, if it contains 1 and
5054:"The Tychonoff product theorem implies the axiom of choice" 4950:
Handbook of Logic and Proof Techniques for Computer Science
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be a set consisting of subsets of some fixed set such that
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is empty, then the trivial ideal {0} is an upper bound for
4998:. Contemporary Mathematics. Vol. 31. pp. 31–33. 4430:, Springer Monographs in Mathematics, Springer, p. 23 2169:(corresponding to the limit ordinal case) or by appending 23:
Mathematical proposition equivalent to the axiom of choice
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to be the set of all well-ordered subsets of a given set
3167:{\displaystyle P=\{f:X'\to U\mid X'\subset X,f(S)\in S\}} 1830:, we need to employ the axiom of choice (explicitly: let 1748:
is an element of the ideal, and so the ideal is equal to
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Every nontrivial ring with unity contains a maximal ideal
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are totally ordered, this is a well-founded definition.
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Pages displaying short descriptions of redirect targets
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contains at least 0 and is not empty. Every element of
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Zorn's lemma can be used to show that every nontrivial
1154:, in other words a maximal linearly independent subset 860:
is not linearly independent. Then there exists vectors
4503: 2368:, where the ordering is with respect to set inclusion. 1897:{\displaystyle B(T)=\{b\in P:\forall t\in T,b\geq t\}} 32:
Zorn's lemma can be used to show that every connected
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has a maximal element with respect to set inclusion.
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chain has an upper bound, as an arbitrary element of
4190: 755:). Finding a maximal linearly independent subset of 434:(with respect to ≤) if there is no other element of 4207: 1333:has an upper bound, that is, there exists an ideal 1143:is linearly independent (because it is a member of 493:if it is greater than or equal to every element of 137:with identity every proper ideal is contained in a 4779: 4759: 4728: 4130: 4110: 4090: 4070: 4044: 4024: 4004: 3978: 3958: 3938: 3903: 3860: 3840: 3820: 3800: 3780: 3743: 3712: 3681: 3661: 3641: 3621: 3601: 3574: 3554: 3534: 3507: 3480: 3454: 3421: 3370: 3322: 3302: 3282: 3236: 3216: 3196: 3166: 3076: 3050: 3012: 2973: 2944: 2905: 2885: 2865: 2825: 2799: 2764: 2744: 2697: 2671: 2651: 2631: 2611: 2591: 2571: 2551: 2531: 2511: 2491: 2467: 2443: 2423: 2403: 2383: 2360: 2340: 2317: 2294: 2274: 2230:Alternatively, one can use the same proof for the 1950: 1896: 1388:to be an ideal, it must satisfy three conditions: 1010: 419:) if it is totally ordered in the inherited order. 2234:. This is the proof given for example in Halmos' 668: 505:is required to be comparable to every element of 7761: 2017:. In fact, the sequence is too long for the set 4317:Analogs under weakenings of the axiom of choice 4150:is an early statement similar to Zorn's lemma. 2218:has a maximal element greater than or equal to 2181:(corresponding to the successor ordinal case). 4391: – Mathematical result on order relations 1101:must contain the others, so there is some set 7079: 5321: 4906:Bulletin of the American Mathematical Society 4625:"A Proof that every Vector Space has a Basis" 4168:The name "Zorn's lemma" appears to be due to 2328:The union of each totally ordered subsets of 1290:contains the trivial ideal {0}. Furthermore, 1185:. Suppose for the sake of contradiction that 5096: 5094: 4839:harvnb error: no target: CITEREFHalmos1960 ( 4820:harvnb error: no target: CITEREFHalmos1960 ( 4548:(2nd ed.). Prentice Hall. p. 875. 4544:Dummit, David S.; Foote, Richard M. (1998). 4291:in topology (to which it is also equivalent) 3178:It is partially ordered by extension; i.e., 3161: 3100: 2745:{\displaystyle {\widetilde {C}}=C\cup \{y\}} 2739: 2733: 1891: 1852: 1298:is the same as finding a maximal element in 759:is the same as finding a maximal element in 673:Zorn's lemma can be used to show that every 608:satisfies the condition that every chain in 352:with order relation ≤ there may be elements 4902:"A remark on method in transfinite algebra" 4543: 3609:'s. Thus, we have shown that each chain in 1764:would contain 1 and would thus be equal to 1329:is non-empty. It is necessary to show that 620:is a chain, as it satisfies the definition 391:can itself be seen as partially ordered by 7737:Positive cone of a partially ordered group 7086: 7072: 5513: 5328: 5314: 5192: 5030:Journal of the London Mathematical Society 4853: 1728:it contains 1. (It is clear that if it is 739:contains the linearly independent subset { 580:Suppose a non-empty partially ordered set 5165: 5116: 5091: 5069: 5027:Hodges, W. (1979). "Krull implies Zorn". 4917: 4877: 3751:. Suppose otherwise; then there is a set 203: 7720:Positive cone of an ordered vector space 5195:Set Theory for the Working Mathematician 5147: 4932: 4801:harvnb error: no target: CITEREFHalmos ( 4683:harvnb error: no target: CITEREFHalmos ( 4452: 2921:Zorn's lemma implies the axiom of choice 1189:is not spanning. Then there exists some 27: 4592: 4561: 4374: – Subset of incomparable elements 4250:Zorn's lemma is also equivalent to the 4012:, a contradiction to the maximality of 2985:), we want to show there is a function 2836:The proof of the weak form is given in 1904:, that is, the set of upper bounds for 845:. To do this, it suffices to show that 663: 592:contains at least one maximal element. 7762: 5335: 5026: 4944: 4834: 4815: 4457:. New York: Blaisdell. pp. 16–17. 4174:Convergence and Uniformity in Topology 1209:} is a linearly independent subset of 632:is in fact non-empty. Conversely, if 7067: 5309: 5237: 5084:J.L. Bell & A.B. Slomson (1969). 4980:J.L. Bell & A.B. Slomson (1969). 4647: 4491: 4440: 4422: 4338: 4285:, to which Zorn's lemma is equivalent 4281:, a result from ring theory known as 2599:. By the hypothesis of Zorn's lemma, 1360:to be the union of all the ideals in 695:}, then the empty set is a basis for 509:but need not itself be an element of 16:For the film by Hollis Frampton, see 5211: 5100: 4899: 4522: 4479: 4467: 4416: 4277:Every commutative unital ring has a 4098:and then shows a maximal element of 3808:is nonempty, it contains an element 2302:satisfies the following properties: 1811:we may then define a bigger element 1783:, in other words a maximal ideal in 1305:To apply Zorn's lemma, take a chain 1080:is totally ordered, one of the sets 849:is a linearly independent subset of 766:To apply Zorn's lemma, take a chain 517:Zorn's lemma can then be stated as: 5148:Campbell, Paul J. (February 1978). 5088:. North Holland Publishing Company. 4712: 2054:arbitrary (this is possible, since 802:is non-empty. We need to show that 501:is not required to be a chain, and 13: 7247:Properties & Types ( 4796: 4678: 4214:Axiom of choice § Equivalents 4161:in 1935, who proposed it as a new 3310:, then we can define the function 2800:{\displaystyle {\widetilde {C}}=C} 2206:subset has an upper bound, and if 1965:, we are going to define elements 1867: 1217:, contradicting the maximality of 644:also satisfies the condition that 628:, and this upper bound shows that 395:the order relation inherited from 152:Zorn's lemma is equivalent to the 14: 7791: 7703:Positive cone of an ordered field 5261: 4654:The American Mathematical Monthly 4622: 4188:" prevails in Poland and Russia. 3582:and is a common extension of all 3371:{\displaystyle X'=\cup _{i}X_{i}} 3084:. For that end, consider the set 2838:Hausdorff maximal principle#Proof 2021:; there are too many ordinals (a 1570:is totally ordered, we know that 727:, there exists a nonzero element 7557:Ordered topological vector space 7093: 7047: 4650:"A simple proof of Zorn's lemma" 4208:Equivalent forms of Zorn's lemma 4193: 3462:. This is well-defined since if 3283:{\displaystyle f_{i}:X_{i}\to U} 1908:. The axiom of choice furnishes 1025:is the union of all the sets in 1001: 987: 956: 931: 129:is compact, and the theorems in 5124: 5078: 5045: 5020: 4987: 4974: 4948:(2002), "The Axiom of Choice", 4938: 4926: 4919:10.1090/S0002-9904-1935-06166-X 4893: 4847: 4828: 4809: 4790: 4672: 4641: 4616: 4406:(sometimes named Tukey's lemma) 4218:Zorn's lemma is equivalent (in 2952:of nonempty sets and its union 2009:: the indices are not just the 2005:. This uncountable sequence is 1790: 160:, in the sense that within ZF ( 5197:. Cambridge University Press. 5193:Ciesielski, Krzysztof (1997). 5150:"The Origin of 'Zorn's Lemma'" 5104:Canadian Mathematical Bulletin 4952:, Springer, pp. 121–126, 4754: 4748: 4723: 4717: 4707: 4666:10.1080/00029890.1991.12000768 4586: 4515: 4497: 4485: 4473: 4461: 4446: 4434: 3927: 3921: 3880: 3416: 3410: 3394: 3388: 3274: 3152: 3146: 3117: 3039: 3033: 3004: 2679:is a maximal element since if 1951:{\displaystyle b:b(T)\in B(T)} 1945: 1939: 1930: 1924: 1846: 1840: 1590:, assume the first case. Both 1538:. Then there exist two ideals 1341:containing all the members of 814:containing all the members of 669:Every vector space has a basis 125:stating that every product of 1: 7514:Series-parallel partial order 7008:History of mathematical logic 5141: 3422:{\displaystyle f(x)=f_{i}(x)} 1666:. Then there exists an ideal 1490:only consists of elements in 1263:be the set consisting of all 782:that is totally ordered). If 711:be the set consisting of all 566:and the chains be non-empty. 171: 166:Hausdorff's maximum principle 97:in 1922 and independently by 7193:Cantor's isomorphism theorem 6933:Primitive recursive function 5167:10.1016/0315-0860(78)90136-2 4854:Kuratowski, Casimir (1922). 4383:Chain-complete partial order 4352:The lemma was referenced on 2974:{\displaystyle U:=\bigcup X} 2519:be the set of all chains in 1772:is explicitly excluded from 1721:ideal. An ideal is equal to 534:has the property that every 7: 7233:Szpilrajn extension theorem 7208:Hausdorff maximal principle 7183:Boolean prime ideal theorem 5298:is another formal proof. ( 5274:Encyclopedia of Mathematics 5238:Moore, Gregory H. (2013) . 5051: 4958:10.1007/978-1-4612-0115-1_9 4648:Lewin, Jonathan W. (1991). 4389:Szpilrajn extension theorem 4365: 4302:, a result that yields the 4252:strong completeness theorem 4227:Hausdorff maximal principle 4148:Hausdorff maximal principle 3713:{\displaystyle X'\subset X} 2579:; i.e., a maximal chain in 2232:Hausdorff maximal principle 1736:is an arbitrary element of 1197:not covered by the span of 1173:. It suffices to show that 616:. Then the empty subset of 473:of a partially ordered set 426:of a partially ordered set 407:of a partially ordered set 387:of a partially ordered set 198:, "How to use Zorn’s lemma" 162:Zermelo–Fraenkel set theory 10: 7796: 7579:Topological vector lattice 5997:Schröder–Bernstein theorem 5724:Monadic predicate calculus 5383:Foundations of mathematics 5286:Zorn's Lemma at ProvenMath 5189:(Springer-Verlag edition). 4993: 4349:is named after the lemma. 4320: 4262:Banach's extension theorem 4211: 4172:, who used it in his book 4141: 3455:{\displaystyle x\in X_{i}} 2241: 1588:Without loss of generality 1376:. We will first show that 909:, not all zero, such that 442:, that is, if there is no 15: 7609: 7537: 7476: 7246: 7175: 7124: 7101: 7043: 7030:Philosophy of mathematics 6979:Automated theorem proving 6961: 6856: 6688: 6581: 6433: 6150: 6126: 6104:Von Neumann–Bernays–Gödel 6049: 5943: 5847: 5745: 5736: 5663: 5598: 5504: 5426: 5343: 4767:or equivalently, that of 4509:"How to use Zorn's lemma" 4453:Wilansky, Albert (1964). 4329:axiom of dependent choice 4323:Axiom of dependent choice 4270:Every vector space has a 4222:) to three main results: 3904:{\displaystyle g|_{X'}=f} 3781:{\displaystyle S\in X-X'} 3051:{\displaystyle f(S)\in S} 1598:are members of the ideal 430:with order relation ≤ is 313:by ≤. Given two elements 109:, the theorem that every 89:was proved (assuming the 7188:Cantor–Bernstein theorem 5086:Models and Ultraproducts 5052:Kelley, John L. (1950). 5039:10.1112/jlms/s2-19.2.285 4982:Models and Ultraproducts 4410: 4045:{\displaystyle \square } 3689:that is defined on some 3013:{\displaystyle f:X\to U} 2247: 1698:and hence an element of 1462:is a nonempty subset of 1395:is a nonempty subset of 1286:is non-trivial, the set 1274:(that is, all ideals in 856:Suppose otherwise, that 790:} is an upper bound for 786:is the empty set, then { 747:is partially ordered by 339:greater than or equal to 7732:Partially ordered group 7552:Specialization preorder 6680:Self-verifying theories 6501:Tarski's axiomatization 5452:Tarski's undefinability 5447:incompleteness theorems 5058:Fundamenta Mathematicae 5004:10.1090/conm/031/763890 4865:Fundamenta Mathematicae 4404:Teichmüller–Tukey lemma 4335:the preceding section. 3197:{\displaystyle f\leq g} 2913:has a maximal element. 2698:{\displaystyle y\geq x} 1364:. We wish to show that 1345:but still smaller than 1229:, and thus, a basis of 833:. We wish to show that 7218:Kruskal's tree theorem 7213:Knaster–Tarski theorem 7203:Dushnik–Miller theorem 7054:Mathematics portal 6665:Proof of impossibility 6313:propositional variable 5623:Propositional calculus 5118:10.4153/CMB-1983-062-5 5033:. s2-19 (2): 285–287. 4781: 4761: 4730: 4505:William Timothy Gowers 4254:of first-order logic. 4132: 4112: 4092: 4072: 4046: 4026: 4006: 4005:{\displaystyle f<g} 3980: 3960: 3940: 3939:{\displaystyle g(S)=s} 3905: 3862: 3842: 3822: 3802: 3782: 3745: 3714: 3683: 3663: 3643: 3629:has an upper bound in 3623: 3603: 3576: 3562:is also an element of 3556: 3536: 3515:is the restriction of 3509: 3482: 3481:{\displaystyle i<j} 3456: 3423: 3372: 3324: 3304: 3284: 3238: 3224:is the restriction of 3218: 3198: 3168: 3078: 3077:{\displaystyle S\in X} 3052: 3014: 2975: 2946: 2907: 2887: 2867: 2827: 2801: 2766: 2746: 2699: 2673: 2653: 2633: 2613: 2593: 2573: 2553: 2533: 2513: 2493: 2469: 2445: 2425: 2405: 2385: 2362: 2342: 2319: 2296: 2276: 1952: 1898: 1602:, therefore their sum 1368:is an upper bound for 1165:Finally, we show that 1029:, there are some sets 1012: 837:is an upper bound for 612:has an upper bound in 554:contains at least one 204:Statement of the lemma 201: 196:William Timothy Gowers 78:contains at least one 51:, is a proposition of 41: 6923:Kolmogorov complexity 6876:Computably enumerable 6776:Model complete theory 6568:Principia Mathematica 5628:Propositional formula 5457:Banach–Tarski paradox 5302:for recent browsers.) 5219:. Mineola, New York: 5071:10.4064/fm-37-1-75-76 4879:10.4064/fm-3-1-76-108 4782: 4762: 4731: 4378:Bourbaki–Witt theorem 4237:Well-ordering theorem 4186:Kuratowski–Zorn lemma 4182:Théorie des Ensembles 4133: 4113: 4093: 4073: 4056:well-ordering theorem 4047: 4027: 4007: 3981: 3961: 3941: 3906: 3863: 3843: 3828:. We can then extend 3823: 3803: 3783: 3746: 3715: 3684: 3664: 3644: 3624: 3604: 3602:{\displaystyle f_{i}} 3577: 3557: 3537: 3535:{\displaystyle f_{j}} 3510: 3508:{\displaystyle f_{i}} 3483: 3457: 3424: 3373: 3325: 3305: 3285: 3239: 3219: 3199: 3169: 3079: 3053: 3015: 2981:(which exists by the 2976: 2947: 2908: 2888: 2868: 2828: 2802: 2767: 2747: 2700: 2674: 2654: 2634: 2614: 2594: 2574: 2554: 2534: 2514: 2494: 2470: 2446: 2426: 2406: 2386: 2363: 2343: 2320: 2297: 2277: 2041:transfinite recursion 1953: 1899: 1225:is a spanning set of 1169:is indeed a basis of 1136:, contradicting that 1108:that contains all of 1013: 529:partially ordered set 208:Preliminary notions: 187: 182:transfinite induction 178:partially ordered set 154:well-ordering theorem 57:partially ordered set 49:Kuratowski–Zorn lemma 31: 7775:Lemmas in set theory 7710:Ordered vector space 6871:Church–Turing thesis 6858:Computability theory 6067:continuum hypothesis 5585:Square of opposition 5443:Gödel's completeness 5154:Historia Mathematica 4996:Axiomatic Set Theory 4771: 4760:{\displaystyle s(P)} 4742: 4695: 4304:completeness theorem 4154:Kazimierz Kuratowski 4122: 4102: 4082: 4062: 4036: 4016: 3990: 3970: 3950: 3915: 3872: 3852: 3832: 3812: 3792: 3755: 3744:{\displaystyle X'=X} 3724: 3693: 3673: 3653: 3633: 3613: 3586: 3566: 3546: 3519: 3492: 3466: 3433: 3382: 3334: 3314: 3294: 3248: 3228: 3208: 3182: 3091: 3062: 3027: 2992: 2956: 2936: 2897: 2877: 2857: 2811: 2776: 2756: 2709: 2683: 2663: 2643: 2623: 2603: 2583: 2563: 2543: 2523: 2503: 2483: 2459: 2435: 2415: 2395: 2375: 2352: 2332: 2309: 2286: 2266: 1912: 1834: 1213:that is larger than 916: 798:. Suppose then that 713:linearly independent 699:. Now, suppose that 664:Example applications 575:(for non-empty sets) 95:Kazimierz Kuratowski 47:, also known as the 7548:Alexandrov topology 7494:Lexicographic order 7453:Well-quasi-ordering 7025:Mathematical object 6916:P versus NP problem 6881:Computable function 6675:Reverse mathematics 6601:Logical consequence 6478:primitive recursive 6473:elementary function 6246:Free/bound variable 6099:Tarski–Grothendieck 5618:Logical connectives 5548:Logical equivalence 5398:Logical consequence 5217:The Axiom of Choice 4455:Functional Analysis 4298:is contained in an 4289:Tychonoff's theorem 4266:Hahn–Banach theorem 2927:Hahn–Banach theorem 2851: —  2826:{\displaystyle y=x} 2619:has an upper bound 2260: —  2192: —  1961:Using the function 1614:, which shows that 1325:. Assume then that 829:of all the sets in 578: —  525: —  311:(partially) ordered 119:Tychonoff's theorem 107:functional analysis 103:Hahn–Banach theorem 55:. It states that a 7529:Transitive closure 7489:Converse/Transpose 7198:Dilworth's theorem 6823:Transfer principle 6786:Semantics of logic 6771:Categorical theory 6747:Non-standard model 6261:Logical connective 5388:Information theory 5337:Mathematical logic 5244:Dover Publications 5221:Dover Publications 4900:Zorn, Max (1935). 4777: 4757: 4726: 4507:(12 August 2008). 4424:Serre, Jean-Pierre 4339:In popular culture 4201:Mathematics portal 4128: 4108: 4088: 4068: 4042: 4022: 4002: 3976: 3956: 3936: 3901: 3858: 3838: 3818: 3798: 3778: 3741: 3720:. We want to show 3710: 3679: 3659: 3639: 3619: 3599: 3572: 3552: 3532: 3505: 3478: 3452: 3419: 3368: 3320: 3300: 3280: 3234: 3214: 3194: 3164: 3074: 3048: 3010: 2971: 2942: 2903: 2883: 2863: 2849: 2823: 2797: 2762: 2742: 2695: 2669: 2649: 2629: 2609: 2589: 2569: 2549: 2529: 2509: 2489: 2465: 2441: 2421: 2401: 2381: 2358: 2338: 2315: 2292: 2272: 2258: 2210:is any element of 2190: 1948: 1894: 1713:Now, we show that 1008: 572: 523: 42: 7757: 7756: 7715:Partially ordered 7524:Symmetric closure 7509:Reflexive closure 7252: 7061: 7060: 6993:Abstract category 6796:Theories of truth 6606:Rule of inference 6596:Natural deduction 6577: 6576: 6122: 6121: 5827:Cartesian product 5732: 5731: 5638:Many-valued logic 5613:Boolean functions 5496:Russell's paradox 5471:diagonal argument 5368:First-order logic 5253:978-0-486-48841-7 5230:978-0-486-46624-8 5204:978-0-521-59465-3 4967:978-1-4612-6619-8 4946:Krantz, Steven G. 4837:, § 17. Exercise. 4818:, § 16. Exercise. 4799:, § 16. Exercise. 4780:{\displaystyle P} 4609:978-3-319-11477-4 4594:Bergman, George M 4578:978-3-319-11477-4 4563:Bergman, George M 4555:978-0-13-569302-5 4537:978-0-387-95385-4 4395:Tarski finiteness 4360:Bart's New Friend 4308:first-order logic 4131:{\displaystyle X} 4111:{\displaystyle P} 4091:{\displaystyle X} 4071:{\displaystyle P} 4025:{\displaystyle f} 3979:{\displaystyle P} 3959:{\displaystyle g} 3861:{\displaystyle g} 3841:{\displaystyle f} 3821:{\displaystyle s} 3801:{\displaystyle S} 3682:{\displaystyle P} 3662:{\displaystyle f} 3642:{\displaystyle P} 3622:{\displaystyle P} 3575:{\displaystyle P} 3555:{\displaystyle f} 3323:{\displaystyle f} 3303:{\displaystyle P} 3237:{\displaystyle g} 3217:{\displaystyle f} 2945:{\displaystyle X} 2906:{\displaystyle P} 2886:{\displaystyle P} 2866:{\displaystyle P} 2847: 2788: 2765:{\displaystyle C} 2721: 2672:{\displaystyle x} 2652:{\displaystyle P} 2632:{\displaystyle x} 2612:{\displaystyle C} 2592:{\displaystyle P} 2572:{\displaystyle F} 2552:{\displaystyle C} 2532:{\displaystyle P} 2512:{\displaystyle F} 2492:{\displaystyle F} 2468:{\displaystyle F} 2444:{\displaystyle F} 2424:{\displaystyle S} 2411:, each subset of 2404:{\displaystyle F} 2384:{\displaystyle S} 2361:{\displaystyle F} 2341:{\displaystyle F} 2318:{\displaystyle F} 2295:{\displaystyle F} 2275:{\displaystyle F} 2256: 2188: 1694:is an element of 1662:is an element of 1562:is an element of 1554:is an element of 1201:. This says that 725:zero vector space 570: 521: 147:algebraic closure 7787: 7499:Linear extension 7248: 7228:Mirsky's theorem 7088: 7081: 7074: 7065: 7064: 7052: 7051: 7003:History of logic 6998:Category of sets 6891:Decision problem 6670:Ordinal analysis 6611:Sequent calculus 6509:Boolean algebras 6449: 6448: 6423: 6394:logical/constant 6148: 6147: 6134: 6057:Zermelo–Fraenkel 5808:Set operations: 5743: 5742: 5680: 5511: 5510: 5491:Löwenheim–Skolem 5378:Formal semantics 5330: 5323: 5316: 5307: 5306: 5282: 5257: 5234: 5208: 5179:Naive set theory 5171: 5169: 5136: 5135: 5128: 5122: 5121: 5120: 5098: 5089: 5082: 5076: 5075: 5073: 5049: 5043: 5042: 5024: 5018: 5017: 4991: 4985: 4978: 4972: 4970: 4942: 4936: 4930: 4924: 4923: 4921: 4897: 4891: 4890: 4888: 4886: 4881: 4861: 4851: 4845: 4844: 4832: 4826: 4825: 4813: 4807: 4806: 4794: 4788: 4786: 4784: 4783: 4778: 4766: 4764: 4763: 4758: 4735: 4733: 4732: 4727: 4716: 4715: 4688: 4676: 4670: 4669: 4645: 4639: 4638: 4636: 4634: 4629: 4620: 4614: 4613: 4590: 4584: 4582: 4559: 4546:Abstract Algebra 4541: 4519: 4513: 4512: 4501: 4495: 4489: 4483: 4477: 4471: 4465: 4459: 4458: 4450: 4444: 4438: 4432: 4431: 4420: 4400: 4358:in the episode " 4203: 4198: 4197: 4137: 4135: 4134: 4129: 4117: 4115: 4114: 4109: 4097: 4095: 4094: 4089: 4077: 4075: 4074: 4069: 4051: 4049: 4048: 4043: 4031: 4029: 4028: 4023: 4011: 4009: 4008: 4003: 3985: 3983: 3982: 3977: 3965: 3963: 3962: 3957: 3945: 3943: 3942: 3937: 3910: 3908: 3907: 3902: 3894: 3893: 3892: 3883: 3867: 3865: 3864: 3859: 3847: 3845: 3844: 3839: 3827: 3825: 3824: 3819: 3807: 3805: 3804: 3799: 3787: 3785: 3784: 3779: 3777: 3750: 3748: 3747: 3742: 3734: 3719: 3717: 3716: 3711: 3703: 3688: 3686: 3685: 3680: 3668: 3666: 3665: 3660: 3648: 3646: 3645: 3640: 3628: 3626: 3625: 3620: 3608: 3606: 3605: 3600: 3598: 3597: 3581: 3579: 3578: 3573: 3561: 3559: 3558: 3553: 3541: 3539: 3538: 3533: 3531: 3530: 3514: 3512: 3511: 3506: 3504: 3503: 3487: 3485: 3484: 3479: 3461: 3459: 3458: 3453: 3451: 3450: 3428: 3426: 3425: 3420: 3409: 3408: 3377: 3375: 3374: 3369: 3367: 3366: 3357: 3356: 3344: 3329: 3327: 3326: 3321: 3309: 3307: 3306: 3301: 3289: 3287: 3286: 3281: 3273: 3272: 3260: 3259: 3243: 3241: 3240: 3235: 3223: 3221: 3220: 3215: 3203: 3201: 3200: 3195: 3173: 3171: 3170: 3165: 3133: 3116: 3083: 3081: 3080: 3075: 3057: 3055: 3054: 3049: 3019: 3017: 3016: 3011: 2980: 2978: 2977: 2972: 2951: 2949: 2948: 2943: 2912: 2910: 2909: 2904: 2892: 2890: 2889: 2884: 2872: 2870: 2869: 2864: 2852: 2832: 2830: 2829: 2824: 2806: 2804: 2803: 2798: 2790: 2789: 2781: 2771: 2769: 2768: 2763: 2751: 2749: 2748: 2743: 2723: 2722: 2714: 2704: 2702: 2701: 2696: 2678: 2676: 2675: 2670: 2658: 2656: 2655: 2650: 2638: 2636: 2635: 2630: 2618: 2616: 2615: 2610: 2598: 2596: 2595: 2590: 2578: 2576: 2575: 2570: 2558: 2556: 2555: 2550: 2538: 2536: 2535: 2530: 2518: 2516: 2515: 2510: 2498: 2496: 2495: 2490: 2474: 2472: 2471: 2466: 2450: 2448: 2447: 2442: 2430: 2428: 2427: 2422: 2410: 2408: 2407: 2402: 2390: 2388: 2387: 2382: 2367: 2365: 2364: 2359: 2347: 2345: 2344: 2339: 2324: 2322: 2321: 2316: 2301: 2299: 2298: 2293: 2281: 2279: 2278: 2273: 2261: 2237:Naive Set Theory 2193: 2177:) to the "last" 2121:} as subsets of 2092:}). Because the 1957: 1955: 1954: 1949: 1903: 1901: 1900: 1895: 1534:are elements of 1017: 1015: 1014: 1009: 1004: 996: 995: 990: 984: 983: 965: 964: 959: 953: 952: 940: 939: 934: 928: 927: 743:}. Furthermore, 579: 576: 526: 309:) is said to be 308: 298: 288: 274: 264: 254: 236: 219:equipped with a 199: 156:and also to the 131:abstract algebra 67:(that is, every 7795: 7794: 7790: 7789: 7788: 7786: 7785: 7784: 7770:Axiom of choice 7760: 7759: 7758: 7753: 7749:Young's lattice 7605: 7533: 7472: 7322:Heyting algebra 7270:Boolean algebra 7242: 7223:Laver's theorem 7171: 7137:Boolean algebra 7132:Binary relation 7120: 7097: 7092: 7062: 7057: 7046: 7039: 6984:Category theory 6974:Algebraic logic 6957: 6928:Lambda calculus 6866:Church encoding 6852: 6828:Truth predicate 6684: 6650:Complete theory 6573: 6442: 6438: 6434: 6429: 6421: 6141: and  6137: 6132: 6118: 6094:New Foundations 6062:axiom of choice 6045: 6007:Gödel numbering 5947: and  5939: 5843: 5728: 5678: 5659: 5608:Boolean algebra 5594: 5558:Equiconsistency 5523:Classical logic 5500: 5481:Halting problem 5469: and  5445: and  5433: and  5432: 5427:Theorems ( 5422: 5339: 5334: 5300:Unicode version 5267: 5264: 5254: 5231: 5205: 5144: 5139: 5130: 5129: 5125: 5099: 5092: 5083: 5079: 5050: 5046: 5025: 5021: 5014: 4992: 4988: 4979: 4975: 4968: 4943: 4939: 4931: 4927: 4912:(10): 667–670. 4898: 4894: 4884: 4882: 4859: 4852: 4848: 4838: 4833: 4829: 4819: 4814: 4810: 4800: 4795: 4791: 4772: 4769: 4768: 4743: 4740: 4739: 4711: 4710: 4696: 4693: 4692: 4682: 4677: 4673: 4646: 4642: 4632: 4630: 4627: 4621: 4617: 4610: 4591: 4587: 4579: 4556: 4538: 4520: 4516: 4502: 4498: 4490: 4486: 4478: 4474: 4466: 4462: 4451: 4447: 4439: 4435: 4421: 4417: 4413: 4398: 4368: 4341: 4325: 4319: 4283:Krull's theorem 4232:Axiom of choice 4216: 4210: 4199: 4192: 4144: 4123: 4120: 4119: 4103: 4100: 4099: 4083: 4080: 4079: 4063: 4060: 4059: 4037: 4034: 4033: 4017: 4014: 4013: 3991: 3988: 3987: 3971: 3968: 3967: 3951: 3948: 3947: 3916: 3913: 3912: 3885: 3884: 3879: 3878: 3873: 3870: 3869: 3853: 3850: 3849: 3833: 3830: 3829: 3813: 3810: 3809: 3793: 3790: 3789: 3770: 3756: 3753: 3752: 3727: 3725: 3722: 3721: 3696: 3694: 3691: 3690: 3674: 3671: 3670: 3654: 3651: 3650: 3634: 3631: 3630: 3614: 3611: 3610: 3593: 3589: 3587: 3584: 3583: 3567: 3564: 3563: 3547: 3544: 3543: 3542:. The function 3526: 3522: 3520: 3517: 3516: 3499: 3495: 3493: 3490: 3489: 3467: 3464: 3463: 3446: 3442: 3434: 3431: 3430: 3404: 3400: 3383: 3380: 3379: 3362: 3358: 3352: 3348: 3337: 3335: 3332: 3331: 3315: 3312: 3311: 3295: 3292: 3291: 3268: 3264: 3255: 3251: 3249: 3246: 3245: 3229: 3226: 3225: 3209: 3206: 3205: 3204:if and only if 3183: 3180: 3179: 3126: 3109: 3092: 3089: 3088: 3063: 3060: 3059: 3028: 3025: 3024: 2993: 2990: 2989: 2957: 2954: 2953: 2937: 2934: 2933: 2923: 2915: 2898: 2895: 2894: 2878: 2875: 2874: 2858: 2855: 2854: 2850: 2812: 2809: 2808: 2780: 2779: 2777: 2774: 2773: 2757: 2754: 2753: 2752:is larger than 2713: 2712: 2710: 2707: 2706: 2684: 2681: 2680: 2664: 2661: 2660: 2644: 2641: 2640: 2624: 2621: 2620: 2604: 2601: 2600: 2584: 2581: 2580: 2564: 2561: 2560: 2544: 2541: 2540: 2524: 2521: 2520: 2504: 2501: 2500: 2484: 2481: 2480: 2477: 2460: 2457: 2456: 2436: 2433: 2432: 2416: 2413: 2412: 2396: 2393: 2392: 2376: 2373: 2372: 2353: 2350: 2349: 2333: 2330: 2329: 2310: 2307: 2306: 2287: 2284: 2283: 2267: 2264: 2263: 2259: 2250: 2228: 2202:in which every 2191: 2112: 2100: 2083: 2070: 2049: 2039:are defined by 2037: 2011:natural numbers 2000: 1996: 1993:< ... < a 1992: 1985: 1978: 1971: 1913: 1910: 1909: 1835: 1832: 1831: 1797:axiom of choice 1793: 1706:is an ideal in 1630:#3 - For every 1622:is a member of 1610:is a member of 1498:#2 - For every 1486:, so the union 1482:is a subset of 1380:is an ideal of 1282:itself). Since 1239: 1142: 1135: 1128: 1121: 1114: 1107: 1100: 1093: 1086: 1067: 1060: 1049: 1042: 1035: 1000: 991: 986: 985: 979: 975: 960: 955: 954: 948: 944: 935: 930: 929: 923: 919: 917: 914: 913: 908: 901: 894: 880: 873: 866: 778:is a subset of 753:inclusion order 671: 666: 594: 588:. Then the set 577: 574: 560: 556:maximal element 550:. Then the set 524: 469:Given a subset 378:totally ordered 300: 290: 280: 266: 256: 246: 228: 221:binary relation 206: 200: 194: 174: 158:axiom of choice 141:and that every 91:axiom of choice 80:maximal element 69:totally ordered 24: 21: 12: 11: 5: 7793: 7783: 7782: 7777: 7772: 7755: 7754: 7752: 7751: 7746: 7741: 7740: 7739: 7729: 7728: 7727: 7722: 7717: 7707: 7706: 7705: 7695: 7690: 7689: 7688: 7683: 7676:Order morphism 7673: 7672: 7671: 7661: 7656: 7651: 7646: 7641: 7640: 7639: 7629: 7624: 7619: 7613: 7611: 7607: 7606: 7604: 7603: 7602: 7601: 7596: 7594:Locally convex 7591: 7586: 7576: 7574:Order topology 7571: 7570: 7569: 7567:Order topology 7564: 7554: 7544: 7542: 7535: 7534: 7532: 7531: 7526: 7521: 7516: 7511: 7506: 7501: 7496: 7491: 7486: 7480: 7478: 7474: 7473: 7471: 7470: 7460: 7450: 7445: 7440: 7435: 7430: 7425: 7420: 7415: 7414: 7413: 7403: 7398: 7397: 7396: 7391: 7386: 7381: 7379:Chain-complete 7371: 7366: 7365: 7364: 7359: 7354: 7349: 7344: 7334: 7329: 7324: 7319: 7314: 7304: 7299: 7294: 7289: 7284: 7279: 7278: 7277: 7267: 7262: 7256: 7254: 7244: 7243: 7241: 7240: 7235: 7230: 7225: 7220: 7215: 7210: 7205: 7200: 7195: 7190: 7185: 7179: 7177: 7173: 7172: 7170: 7169: 7164: 7159: 7154: 7149: 7144: 7139: 7134: 7128: 7126: 7122: 7121: 7119: 7118: 7113: 7108: 7102: 7099: 7098: 7091: 7090: 7083: 7076: 7068: 7059: 7058: 7044: 7041: 7040: 7038: 7037: 7032: 7027: 7022: 7017: 7016: 7015: 7005: 7000: 6995: 6986: 6981: 6976: 6971: 6969:Abstract logic 6965: 6963: 6959: 6958: 6956: 6955: 6950: 6948:Turing machine 6945: 6940: 6935: 6930: 6925: 6920: 6919: 6918: 6913: 6908: 6903: 6898: 6888: 6886:Computable set 6883: 6878: 6873: 6868: 6862: 6860: 6854: 6853: 6851: 6850: 6845: 6840: 6835: 6830: 6825: 6820: 6815: 6814: 6813: 6808: 6803: 6793: 6788: 6783: 6781:Satisfiability 6778: 6773: 6768: 6767: 6766: 6756: 6755: 6754: 6744: 6743: 6742: 6737: 6732: 6727: 6722: 6712: 6711: 6710: 6705: 6698:Interpretation 6694: 6692: 6686: 6685: 6683: 6682: 6677: 6672: 6667: 6662: 6652: 6647: 6646: 6645: 6644: 6643: 6633: 6628: 6618: 6613: 6608: 6603: 6598: 6593: 6587: 6585: 6579: 6578: 6575: 6574: 6572: 6571: 6563: 6562: 6561: 6560: 6555: 6554: 6553: 6548: 6543: 6523: 6522: 6521: 6519:minimal axioms 6516: 6505: 6504: 6503: 6492: 6491: 6490: 6485: 6480: 6475: 6470: 6465: 6452: 6450: 6431: 6430: 6428: 6427: 6426: 6425: 6413: 6408: 6407: 6406: 6401: 6396: 6391: 6381: 6376: 6371: 6366: 6365: 6364: 6359: 6349: 6348: 6347: 6342: 6337: 6332: 6322: 6317: 6316: 6315: 6310: 6305: 6295: 6294: 6293: 6288: 6283: 6278: 6273: 6268: 6258: 6253: 6248: 6243: 6242: 6241: 6236: 6231: 6226: 6216: 6211: 6209:Formation rule 6206: 6201: 6200: 6199: 6194: 6184: 6183: 6182: 6172: 6167: 6162: 6157: 6151: 6145: 6128:Formal systems 6124: 6123: 6120: 6119: 6117: 6116: 6111: 6106: 6101: 6096: 6091: 6086: 6081: 6076: 6071: 6070: 6069: 6064: 6053: 6051: 6047: 6046: 6044: 6043: 6042: 6041: 6031: 6026: 6025: 6024: 6017:Large cardinal 6014: 6009: 6004: 5999: 5994: 5980: 5979: 5978: 5973: 5968: 5953: 5951: 5941: 5940: 5938: 5937: 5936: 5935: 5930: 5925: 5915: 5910: 5905: 5900: 5895: 5890: 5885: 5880: 5875: 5870: 5865: 5860: 5854: 5852: 5845: 5844: 5842: 5841: 5840: 5839: 5834: 5829: 5824: 5819: 5814: 5806: 5805: 5804: 5799: 5789: 5784: 5782:Extensionality 5779: 5777:Ordinal number 5774: 5764: 5759: 5758: 5757: 5746: 5740: 5734: 5733: 5730: 5729: 5727: 5726: 5721: 5716: 5711: 5706: 5701: 5696: 5695: 5694: 5684: 5683: 5682: 5669: 5667: 5661: 5660: 5658: 5657: 5656: 5655: 5650: 5645: 5635: 5630: 5625: 5620: 5615: 5610: 5604: 5602: 5596: 5595: 5593: 5592: 5587: 5582: 5577: 5572: 5567: 5562: 5561: 5560: 5550: 5545: 5540: 5535: 5530: 5525: 5519: 5517: 5508: 5502: 5501: 5499: 5498: 5493: 5488: 5483: 5478: 5473: 5461:Cantor's  5459: 5454: 5449: 5439: 5437: 5424: 5423: 5421: 5420: 5415: 5410: 5405: 5400: 5395: 5390: 5385: 5380: 5375: 5370: 5365: 5360: 5359: 5358: 5347: 5345: 5341: 5340: 5333: 5332: 5325: 5318: 5310: 5304: 5303: 5289: 5283: 5263: 5262:External links 5260: 5259: 5258: 5252: 5235: 5229: 5209: 5203: 5190: 5172: 5143: 5140: 5138: 5137: 5123: 5111:(3): 365–367, 5090: 5077: 5044: 5019: 5012: 4986: 4973: 4966: 4937: 4925: 4892: 4846: 4827: 4808: 4789: 4776: 4756: 4753: 4750: 4747: 4737: 4736: 4725: 4722: 4719: 4714: 4709: 4706: 4703: 4700: 4671: 4660:(4): 353–354. 4640: 4615: 4608: 4585: 4577: 4554: 4536: 4514: 4496: 4484: 4472: 4460: 4445: 4433: 4414: 4412: 4409: 4408: 4407: 4401: 4392: 4386: 4380: 4375: 4367: 4364: 4343:The 1970 film 4340: 4337: 4318: 4315: 4311: 4310: 4292: 4286: 4275: 4268: 4241: 4240: 4234: 4229: 4209: 4206: 4205: 4204: 4143: 4140: 4127: 4107: 4087: 4067: 4041: 4021: 4001: 3998: 3995: 3975: 3955: 3935: 3932: 3929: 3926: 3923: 3920: 3900: 3897: 3891: 3888: 3882: 3877: 3857: 3848:to a function 3837: 3817: 3797: 3776: 3773: 3769: 3766: 3763: 3760: 3740: 3737: 3733: 3730: 3709: 3706: 3702: 3699: 3678: 3658: 3638: 3618: 3596: 3592: 3571: 3551: 3529: 3525: 3502: 3498: 3477: 3474: 3471: 3449: 3445: 3441: 3438: 3418: 3415: 3412: 3407: 3403: 3399: 3396: 3393: 3390: 3387: 3365: 3361: 3355: 3351: 3347: 3343: 3340: 3319: 3299: 3290:is a chain in 3279: 3276: 3271: 3267: 3263: 3258: 3254: 3233: 3213: 3193: 3190: 3187: 3176: 3175: 3163: 3160: 3157: 3154: 3151: 3148: 3145: 3142: 3139: 3136: 3132: 3129: 3125: 3122: 3119: 3115: 3112: 3108: 3105: 3102: 3099: 3096: 3073: 3070: 3067: 3047: 3044: 3041: 3038: 3035: 3032: 3021: 3020: 3009: 3006: 3003: 3000: 2997: 2983:axiom of union 2970: 2967: 2964: 2961: 2941: 2922: 2919: 2902: 2882: 2862: 2845: 2822: 2819: 2816: 2796: 2793: 2787: 2784: 2761: 2741: 2738: 2735: 2732: 2729: 2726: 2720: 2717: 2694: 2691: 2688: 2668: 2648: 2628: 2608: 2588: 2568: 2548: 2528: 2508: 2488: 2464: 2453: 2452: 2440: 2420: 2400: 2380: 2369: 2357: 2337: 2326: 2314: 2291: 2271: 2254: 2249: 2246: 2186: 2108: 2096: 2079: 2066: 2047: 2035: 1998: 1994: 1990: 1983: 1976: 1969: 1947: 1944: 1941: 1938: 1935: 1932: 1929: 1926: 1923: 1920: 1917: 1893: 1890: 1887: 1884: 1881: 1878: 1875: 1872: 1869: 1866: 1863: 1860: 1857: 1854: 1851: 1848: 1845: 1842: 1839: 1792: 1789: 1756:were equal to 1726:if and only if 1646:, the product 1455: 1454: 1445:, the product 1427: 1400: 1238: 1235: 1140: 1133: 1126: 1119: 1112: 1105: 1098: 1091: 1084: 1065: 1058: 1047: 1040: 1033: 1019: 1018: 1007: 1003: 999: 994: 989: 982: 978: 974: 971: 968: 963: 958: 951: 947: 943: 938: 933: 926: 922: 906: 899: 892: 878: 871: 864: 670: 667: 665: 662: 568: 519: 515: 514: 467: 420: 381: 337:is said to be 205: 202: 192: 185:Zorn's lemma. 173: 170: 127:compact spaces 22: 9: 6: 4: 3: 2: 7792: 7781: 7778: 7776: 7773: 7771: 7768: 7767: 7765: 7750: 7747: 7745: 7742: 7738: 7735: 7734: 7733: 7730: 7726: 7723: 7721: 7718: 7716: 7713: 7712: 7711: 7708: 7704: 7701: 7700: 7699: 7698:Ordered field 7696: 7694: 7691: 7687: 7684: 7682: 7679: 7678: 7677: 7674: 7670: 7667: 7666: 7665: 7662: 7660: 7657: 7655: 7654:Hasse diagram 7652: 7650: 7647: 7645: 7642: 7638: 7635: 7634: 7633: 7632:Comparability 7630: 7628: 7625: 7623: 7620: 7618: 7615: 7614: 7612: 7608: 7600: 7597: 7595: 7592: 7590: 7587: 7585: 7582: 7581: 7580: 7577: 7575: 7572: 7568: 7565: 7563: 7560: 7559: 7558: 7555: 7553: 7549: 7546: 7545: 7543: 7540: 7536: 7530: 7527: 7525: 7522: 7520: 7517: 7515: 7512: 7510: 7507: 7505: 7504:Product order 7502: 7500: 7497: 7495: 7492: 7490: 7487: 7485: 7482: 7481: 7479: 7477:Constructions 7475: 7469: 7465: 7461: 7458: 7454: 7451: 7449: 7446: 7444: 7441: 7439: 7436: 7434: 7431: 7429: 7426: 7424: 7421: 7419: 7416: 7412: 7409: 7408: 7407: 7404: 7402: 7399: 7395: 7392: 7390: 7387: 7385: 7382: 7380: 7377: 7376: 7375: 7374:Partial order 7372: 7370: 7367: 7363: 7362:Join and meet 7360: 7358: 7355: 7353: 7350: 7348: 7345: 7343: 7340: 7339: 7338: 7335: 7333: 7330: 7328: 7325: 7323: 7320: 7318: 7315: 7313: 7309: 7305: 7303: 7300: 7298: 7295: 7293: 7290: 7288: 7285: 7283: 7280: 7276: 7273: 7272: 7271: 7268: 7266: 7263: 7261: 7260:Antisymmetric 7258: 7257: 7255: 7251: 7245: 7239: 7236: 7234: 7231: 7229: 7226: 7224: 7221: 7219: 7216: 7214: 7211: 7209: 7206: 7204: 7201: 7199: 7196: 7194: 7191: 7189: 7186: 7184: 7181: 7180: 7178: 7174: 7168: 7167:Weak ordering 7165: 7163: 7160: 7158: 7155: 7153: 7152:Partial order 7150: 7148: 7145: 7143: 7140: 7138: 7135: 7133: 7130: 7129: 7127: 7123: 7117: 7114: 7112: 7109: 7107: 7104: 7103: 7100: 7096: 7089: 7084: 7082: 7077: 7075: 7070: 7069: 7066: 7056: 7055: 7050: 7042: 7036: 7033: 7031: 7028: 7026: 7023: 7021: 7018: 7014: 7011: 7010: 7009: 7006: 7004: 7001: 6999: 6996: 6994: 6990: 6987: 6985: 6982: 6980: 6977: 6975: 6972: 6970: 6967: 6966: 6964: 6960: 6954: 6951: 6949: 6946: 6944: 6943:Recursive set 6941: 6939: 6936: 6934: 6931: 6929: 6926: 6924: 6921: 6917: 6914: 6912: 6909: 6907: 6904: 6902: 6899: 6897: 6894: 6893: 6892: 6889: 6887: 6884: 6882: 6879: 6877: 6874: 6872: 6869: 6867: 6864: 6863: 6861: 6859: 6855: 6849: 6846: 6844: 6841: 6839: 6836: 6834: 6831: 6829: 6826: 6824: 6821: 6819: 6816: 6812: 6809: 6807: 6804: 6802: 6799: 6798: 6797: 6794: 6792: 6789: 6787: 6784: 6782: 6779: 6777: 6774: 6772: 6769: 6765: 6762: 6761: 6760: 6757: 6753: 6752:of arithmetic 6750: 6749: 6748: 6745: 6741: 6738: 6736: 6733: 6731: 6728: 6726: 6723: 6721: 6718: 6717: 6716: 6713: 6709: 6706: 6704: 6701: 6700: 6699: 6696: 6695: 6693: 6691: 6687: 6681: 6678: 6676: 6673: 6671: 6668: 6666: 6663: 6660: 6659:from ZFC 6656: 6653: 6651: 6648: 6642: 6639: 6638: 6637: 6634: 6632: 6629: 6627: 6624: 6623: 6622: 6619: 6617: 6614: 6612: 6609: 6607: 6604: 6602: 6599: 6597: 6594: 6592: 6589: 6588: 6586: 6584: 6580: 6570: 6569: 6565: 6564: 6559: 6558:non-Euclidean 6556: 6552: 6549: 6547: 6544: 6542: 6541: 6537: 6536: 6534: 6531: 6530: 6528: 6524: 6520: 6517: 6515: 6512: 6511: 6510: 6506: 6502: 6499: 6498: 6497: 6493: 6489: 6486: 6484: 6481: 6479: 6476: 6474: 6471: 6469: 6466: 6464: 6461: 6460: 6458: 6454: 6453: 6451: 6446: 6440: 6435:Example  6432: 6424: 6419: 6418: 6417: 6414: 6412: 6409: 6405: 6402: 6400: 6397: 6395: 6392: 6390: 6387: 6386: 6385: 6382: 6380: 6377: 6375: 6372: 6370: 6367: 6363: 6360: 6358: 6355: 6354: 6353: 6350: 6346: 6343: 6341: 6338: 6336: 6333: 6331: 6328: 6327: 6326: 6323: 6321: 6318: 6314: 6311: 6309: 6306: 6304: 6301: 6300: 6299: 6296: 6292: 6289: 6287: 6284: 6282: 6279: 6277: 6274: 6272: 6269: 6267: 6264: 6263: 6262: 6259: 6257: 6254: 6252: 6249: 6247: 6244: 6240: 6237: 6235: 6232: 6230: 6227: 6225: 6222: 6221: 6220: 6217: 6215: 6212: 6210: 6207: 6205: 6202: 6198: 6195: 6193: 6192:by definition 6190: 6189: 6188: 6185: 6181: 6178: 6177: 6176: 6173: 6171: 6168: 6166: 6163: 6161: 6158: 6156: 6153: 6152: 6149: 6146: 6144: 6140: 6135: 6129: 6125: 6115: 6112: 6110: 6107: 6105: 6102: 6100: 6097: 6095: 6092: 6090: 6087: 6085: 6082: 6080: 6079:Kripke–Platek 6077: 6075: 6072: 6068: 6065: 6063: 6060: 6059: 6058: 6055: 6054: 6052: 6048: 6040: 6037: 6036: 6035: 6032: 6030: 6027: 6023: 6020: 6019: 6018: 6015: 6013: 6010: 6008: 6005: 6003: 6000: 5998: 5995: 5992: 5988: 5984: 5981: 5977: 5974: 5972: 5969: 5967: 5964: 5963: 5962: 5958: 5955: 5954: 5952: 5950: 5946: 5942: 5934: 5931: 5929: 5926: 5924: 5923:constructible 5921: 5920: 5919: 5916: 5914: 5911: 5909: 5906: 5904: 5901: 5899: 5896: 5894: 5891: 5889: 5886: 5884: 5881: 5879: 5876: 5874: 5871: 5869: 5866: 5864: 5861: 5859: 5856: 5855: 5853: 5851: 5846: 5838: 5835: 5833: 5830: 5828: 5825: 5823: 5820: 5818: 5815: 5813: 5810: 5809: 5807: 5803: 5800: 5798: 5795: 5794: 5793: 5790: 5788: 5785: 5783: 5780: 5778: 5775: 5773: 5769: 5765: 5763: 5760: 5756: 5753: 5752: 5751: 5748: 5747: 5744: 5741: 5739: 5735: 5725: 5722: 5720: 5717: 5715: 5712: 5710: 5707: 5705: 5702: 5700: 5697: 5693: 5690: 5689: 5688: 5685: 5681: 5676: 5675: 5674: 5671: 5670: 5668: 5666: 5662: 5654: 5651: 5649: 5646: 5644: 5641: 5640: 5639: 5636: 5634: 5631: 5629: 5626: 5624: 5621: 5619: 5616: 5614: 5611: 5609: 5606: 5605: 5603: 5601: 5600:Propositional 5597: 5591: 5588: 5586: 5583: 5581: 5578: 5576: 5573: 5571: 5568: 5566: 5563: 5559: 5556: 5555: 5554: 5551: 5549: 5546: 5544: 5541: 5539: 5536: 5534: 5531: 5529: 5528:Logical truth 5526: 5524: 5521: 5520: 5518: 5516: 5512: 5509: 5507: 5503: 5497: 5494: 5492: 5489: 5487: 5484: 5482: 5479: 5477: 5474: 5472: 5468: 5464: 5460: 5458: 5455: 5453: 5450: 5448: 5444: 5441: 5440: 5438: 5436: 5430: 5425: 5419: 5416: 5414: 5411: 5409: 5406: 5404: 5401: 5399: 5396: 5394: 5391: 5389: 5386: 5384: 5381: 5379: 5376: 5374: 5371: 5369: 5366: 5364: 5361: 5357: 5354: 5353: 5352: 5349: 5348: 5346: 5342: 5338: 5331: 5326: 5324: 5319: 5317: 5312: 5311: 5308: 5301: 5297: 5293: 5290: 5287: 5284: 5280: 5276: 5275: 5270: 5266: 5265: 5255: 5249: 5245: 5241: 5236: 5232: 5226: 5222: 5218: 5214: 5210: 5206: 5200: 5196: 5191: 5188: 5187:0-387-90092-6 5184: 5180: 5176: 5173: 5168: 5163: 5159: 5155: 5151: 5146: 5145: 5133: 5127: 5119: 5114: 5110: 5106: 5105: 5097: 5095: 5087: 5081: 5072: 5067: 5063: 5059: 5055: 5048: 5040: 5036: 5032: 5031: 5023: 5015: 5013:9780821850268 5009: 5005: 5001: 4997: 4990: 4983: 4977: 4969: 4963: 4959: 4955: 4951: 4947: 4941: 4935:, p. 82. 4934: 4933:Campbell 1978 4929: 4920: 4915: 4911: 4907: 4903: 4896: 4880: 4875: 4871: 4868:(in French). 4867: 4866: 4857: 4850: 4842: 4836: 4831: 4823: 4817: 4812: 4804: 4798: 4793: 4774: 4751: 4745: 4720: 4704: 4701: 4698: 4691: 4690: 4686: 4680: 4675: 4667: 4663: 4659: 4655: 4651: 4644: 4626: 4619: 4611: 4605: 4601: 4600: 4595: 4589: 4580: 4574: 4570: 4569: 4564: 4557: 4551: 4547: 4539: 4533: 4529: 4525: 4521:For example, 4518: 4510: 4506: 4500: 4494:, p. 168 4493: 4488: 4481: 4476: 4469: 4464: 4456: 4449: 4443:, p. 168 4442: 4437: 4429: 4425: 4419: 4415: 4405: 4402: 4396: 4393: 4390: 4387: 4384: 4381: 4379: 4376: 4373: 4370: 4369: 4363: 4361: 4357: 4356: 4350: 4348: 4347: 4336: 4332: 4330: 4324: 4314: 4309: 4305: 4301: 4297: 4296:proper filter 4293: 4290: 4287: 4284: 4280: 4279:maximal ideal 4276: 4273: 4269: 4267: 4263: 4260: 4259: 4258: 4255: 4253: 4248: 4246: 4238: 4235: 4233: 4230: 4228: 4225: 4224: 4223: 4221: 4215: 4202: 4196: 4191: 4189: 4187: 4183: 4179: 4175: 4171: 4166: 4164: 4160: 4155: 4151: 4149: 4139: 4125: 4105: 4085: 4065: 4057: 4052: 4039: 4019: 3999: 3996: 3993: 3973: 3953: 3933: 3930: 3924: 3918: 3898: 3895: 3889: 3886: 3875: 3855: 3835: 3815: 3795: 3774: 3771: 3767: 3764: 3761: 3758: 3738: 3735: 3731: 3728: 3707: 3704: 3700: 3697: 3676: 3656: 3636: 3616: 3594: 3590: 3569: 3549: 3527: 3523: 3500: 3496: 3475: 3472: 3469: 3447: 3443: 3439: 3436: 3413: 3405: 3401: 3397: 3391: 3385: 3363: 3359: 3353: 3349: 3345: 3341: 3338: 3330:on the union 3317: 3297: 3277: 3269: 3265: 3261: 3256: 3252: 3231: 3211: 3191: 3188: 3185: 3158: 3155: 3149: 3143: 3140: 3137: 3134: 3130: 3127: 3123: 3120: 3113: 3110: 3106: 3103: 3097: 3094: 3087: 3086: 3085: 3071: 3068: 3065: 3045: 3042: 3036: 3030: 3007: 3001: 2998: 2995: 2988: 2987: 2986: 2984: 2968: 2965: 2962: 2959: 2939: 2930: 2928: 2918: 2914: 2900: 2880: 2860: 2844: 2841: 2839: 2834: 2820: 2817: 2814: 2794: 2791: 2785: 2782: 2759: 2736: 2730: 2727: 2724: 2718: 2715: 2692: 2689: 2686: 2666: 2646: 2626: 2606: 2586: 2566: 2546: 2526: 2506: 2486: 2476: 2462: 2438: 2418: 2398: 2378: 2371:For each set 2370: 2355: 2335: 2327: 2312: 2305: 2304: 2303: 2289: 2269: 2253: 2245: 2243: 2239: 2238: 2233: 2227: 2225: 2221: 2217: 2213: 2209: 2205: 2201: 2197: 2185: 2182: 2180: 2176: 2172: 2168: 2164: 2160: 2156: 2152: 2148: 2144: 2140: 2136: 2132: 2128: 2124: 2120: 2116: 2111: 2107: 2102: 2099: 2095: 2091: 2087: 2082: 2078: 2074: 2069: 2065: 2061: 2057: 2053: 2046: 2042: 2038: 2030: 2028: 2024: 2020: 2016: 2012: 2008: 2004: 1989: 1982: 1975: 1968: 1964: 1959: 1942: 1936: 1933: 1927: 1921: 1918: 1915: 1907: 1888: 1885: 1882: 1879: 1876: 1873: 1870: 1864: 1861: 1858: 1855: 1849: 1843: 1837: 1829: 1826: 1822: 1818: 1814: 1810: 1806: 1802: 1798: 1788: 1786: 1782: 1777: 1775: 1771: 1767: 1763: 1759: 1755: 1751: 1747: 1743: 1739: 1735: 1731: 1727: 1724: 1720: 1716: 1711: 1709: 1705: 1701: 1697: 1693: 1689: 1685: 1681: 1677: 1673: 1669: 1665: 1661: 1656: 1655: 1653: 1649: 1645: 1641: 1637: 1633: 1627: 1625: 1621: 1617: 1613: 1609: 1605: 1601: 1597: 1593: 1589: 1585: 1581: 1577: 1573: 1569: 1565: 1561: 1557: 1553: 1549: 1545: 1541: 1537: 1533: 1529: 1524: 1523: 1521: 1517: 1513: 1509: 1505: 1501: 1495: 1493: 1489: 1485: 1481: 1477: 1473: 1468: 1467: 1465: 1461: 1452: 1448: 1444: 1440: 1436: 1432: 1428: 1425: 1421: 1417: 1413: 1409: 1405: 1401: 1398: 1394: 1391: 1390: 1389: 1387: 1383: 1379: 1375: 1371: 1367: 1363: 1359: 1354: 1352: 1348: 1344: 1340: 1336: 1332: 1328: 1324: 1320: 1316: 1312: 1308: 1303: 1301: 1297: 1293: 1289: 1285: 1281: 1277: 1273: 1269: 1266: 1262: 1257: 1255: 1254:maximal ideal 1251: 1247: 1244: 1234: 1232: 1228: 1224: 1221:. Therefore, 1220: 1216: 1212: 1208: 1204: 1200: 1196: 1192: 1188: 1184: 1180: 1176: 1172: 1168: 1163: 1161: 1157: 1153: 1148: 1146: 1139: 1132: 1125: 1118: 1111: 1104: 1097: 1090: 1083: 1079: 1075: 1072:= 1, 2, ..., 1071: 1064: 1057: 1053: 1046: 1039: 1032: 1028: 1024: 1005: 997: 992: 980: 976: 972: 969: 966: 961: 949: 945: 941: 936: 924: 920: 912: 911: 910: 905: 898: 891: 888: 884: 877: 870: 863: 859: 854: 852: 848: 844: 840: 836: 832: 828: 824: 819: 817: 813: 809: 805: 801: 797: 793: 789: 785: 781: 777: 773: 769: 764: 762: 758: 754: 750: 749:set inclusion 746: 742: 738: 734: 730: 726: 722: 718: 714: 710: 706: 702: 698: 694: 690: 685: 683: 679: 676: 661: 659: 653: 651: 647: 643: 639: 635: 631: 627: 623: 619: 615: 611: 607: 603: 599: 593: 591: 587: 583: 567: 565: 559: 557: 553: 549: 545: 541: 537: 533: 530: 518: 512: 508: 504: 500: 496: 492: 488: 484: 480: 477:, an element 476: 472: 468: 465: 461: 457: 453: 449: 445: 441: 438:greater than 437: 433: 429: 425: 421: 418: 414: 410: 406: 402: 398: 394: 390: 386: 383:Every subset 382: 379: 375: 371: 367: 363: 360:with neither 359: 355: 351: 347: 343: 340: 336: 332: 328: 324: 320: 316: 312: 307: 303: 297: 293: 287: 283: 278: 273: 269: 263: 259: 253: 249: 244: 243:antisymmetric 240: 235: 231: 226: 222: 218: 215: 211: 210: 209: 197: 191: 186: 183: 179: 169: 167: 163: 159: 155: 150: 148: 144: 140: 139:maximal ideal 136: 132: 128: 124: 120: 116: 112: 108: 104: 100: 96: 92: 88: 83: 81: 77: 73: 70: 66: 62: 58: 54: 50: 46: 39: 38:spanning tree 35: 30: 26: 19: 7780:Order theory 7541:& Orders 7519:Star product 7448:Well-founded 7401:Prefix order 7357:Distributive 7347:Complemented 7317:Foundational 7282:Completeness 7238:Zorn's lemma 7237: 7142:Cyclic order 7125:Key concepts 7095:Order theory 7045: 6843:Ultraproduct 6690:Model theory 6655:Independence 6591:Formal proof 6583:Proof theory 6566: 6539: 6496:real numbers 6468:second-order 6379:Substitution 6256:Metalanguage 6197:conservative 6170:Axiom schema 6114:Constructive 6084:Morse–Kelley 6050:Set theories 6029:Aleph number 6022:inaccessible 5928:Grothendieck 5812:intersection 5699:Higher-order 5687:Second-order 5633:Truth tables 5590:Venn diagram 5373:Formal proof 5292:Zorn's Lemma 5272: 5269:"Zorn lemma" 5239: 5216: 5213:Jech, Thomas 5194: 5178: 5160:(1): 77–89. 5157: 5153: 5126: 5108: 5102: 5085: 5080: 5061: 5057: 5047: 5028: 5022: 4995: 4989: 4981: 4976: 4949: 4940: 4928: 4909: 4905: 4895: 4883:. Retrieved 4869: 4863: 4849: 4830: 4811: 4792: 4674: 4657: 4653: 4643: 4631:. Retrieved 4623:Smits, Tim. 4618: 4598: 4588: 4567: 4545: 4527: 4517: 4499: 4487: 4475: 4463: 4454: 4448: 4436: 4427: 4418: 4355:The Simpsons 4353: 4351: 4344: 4342: 4333: 4326: 4312: 4256: 4249: 4242: 4217: 4181: 4173: 4167: 4152: 4145: 4053: 3177: 3022: 2932:Given a set 2931: 2924: 2916: 2846: 2842: 2835: 2659:. Then this 2478: 2454: 2325:is nonempty. 2255: 2251: 2242:§ Proof 2235: 2229: 2223: 2219: 2215: 2211: 2207: 2204:well-ordered 2195: 2187: 2183: 2178: 2174: 2170: 2166: 2162: 2158: 2154: 2150: 2146: 2142: 2138: 2134: 2130: 2126: 2122: 2118: 2114: 2109: 2105: 2103: 2097: 2093: 2089: 2085: 2080: 2076: 2072: 2067: 2063: 2059: 2055: 2051: 2044: 2033: 2031: 2026: 2023:proper class 2018: 2006: 2002: 1987: 1980: 1973: 1966: 1962: 1960: 1905: 1827: 1820: 1816: 1812: 1808: 1804: 1800: 1794: 1791:Proof sketch 1784: 1780: 1778: 1773: 1769: 1765: 1761: 1757: 1753: 1749: 1745: 1741: 1737: 1733: 1729: 1722: 1718: 1714: 1712: 1707: 1703: 1699: 1695: 1691: 1687: 1683: 1679: 1675: 1671: 1667: 1663: 1659: 1657: 1651: 1647: 1643: 1639: 1635: 1631: 1629: 1628: 1623: 1619: 1615: 1611: 1607: 1603: 1599: 1595: 1591: 1583: 1579: 1575: 1571: 1567: 1563: 1559: 1555: 1551: 1547: 1543: 1539: 1535: 1531: 1527: 1525: 1519: 1515: 1511: 1507: 1503: 1499: 1497: 1496: 1491: 1487: 1483: 1479: 1475: 1471: 1469: 1463: 1459: 1457: 1456: 1450: 1446: 1442: 1438: 1434: 1430: 1423: 1419: 1415: 1411: 1407: 1403: 1396: 1392: 1385: 1381: 1377: 1373: 1369: 1365: 1361: 1357: 1355: 1350: 1346: 1342: 1338: 1334: 1330: 1326: 1322: 1318: 1314: 1310: 1306: 1304: 1299: 1295: 1291: 1287: 1283: 1279: 1275: 1271: 1264: 1260: 1258: 1245: 1240: 1230: 1226: 1222: 1218: 1214: 1210: 1206: 1202: 1198: 1194: 1190: 1186: 1182: 1179:spanning set 1174: 1170: 1166: 1164: 1159: 1155: 1151: 1149: 1144: 1137: 1130: 1123: 1116: 1109: 1102: 1095: 1088: 1081: 1077: 1073: 1069: 1062: 1055: 1051: 1044: 1037: 1030: 1026: 1022: 1020: 903: 896: 889: 882: 875: 868: 861: 857: 855: 850: 846: 842: 838: 834: 830: 822: 820: 815: 811: 807: 803: 799: 795: 791: 787: 783: 779: 775: 771: 767: 765: 760: 756: 744: 740: 736: 732: 728: 720: 716: 708: 704: 700: 696: 692: 688: 686: 677: 675:vector space 672: 657: 654: 649: 645: 641: 637: 633: 629: 625: 617: 613: 609: 605: 601: 597: 595: 589: 585: 581: 571:Zorn's lemma 569: 563: 561: 551: 547: 539: 531: 522:Zorn's lemma 520: 516: 510: 506: 502: 498: 494: 490: 482: 478: 474: 470: 463: 459: 455: 451: 447: 443: 439: 435: 427: 423: 416: 411:is called a 408: 404: 400: 396: 388: 384: 373: 369: 365: 361: 357: 353: 349: 341: 334: 330: 326: 322: 318: 314: 305: 301: 295: 291: 285: 281: 271: 267: 261: 257: 251: 247: 238: 233: 229: 216: 207: 188: 175: 151: 111:vector space 84: 61:upper bounds 48: 45:Zorn's lemma 44: 43: 25: 7725:Riesz space 7686:Isomorphism 7562:Normal cone 7484:Composition 7418:Semilattice 7327:Homogeneous 7312:Equivalence 7162:Total order 6953:Type theory 6901:undecidable 6833:Truth value 6720:equivalence 6399:non-logical 6012:Enumeration 6002:Isomorphism 5949:cardinality 5933:Von Neumann 5898:Ultrafilter 5863:Uncountable 5797:equivalence 5714:Quantifiers 5704:Fixed-point 5673:First-order 5553:Consistency 5538:Proposition 5515:Traditional 5486:Lindström's 5476:Compactness 5418:Type theory 5363:Cardinality 5175:Paul Halmos 4835:Halmos 1960 4816:Halmos 1960 4524:Lang, Serge 4482:, p. 9 4346:Zorns Lemma 4300:ultrafilter 3868:by setting 3378:by setting 2133:where each 2007:really long 1819:), because 1252:contains a 723:is not the 715:subsets of 544:upper bound 487:upper bound 422:An element 403:. A subset 393:restricting 265:hold, then 76:necessarily 59:containing 18:Zorns Lemma 7764:Categories 7693:Order type 7627:Cofinality 7468:Well-order 7443:Transitive 7332:Idempotent 7265:Asymmetric 6764:elementary 6457:arithmetic 6325:Quantifier 6303:functional 6175:Expression 5893:Transitive 5837:identities 5822:complement 5755:hereditary 5738:Set theory 5142:References 4872:: 76–108. 4492:Moore 2013 4441:Moore 2013 4321:See also: 4245:Jerry Bona 4212:See also: 4170:John Tukey 3023:such that 2141:satisfies 2043:: we pick 2013:, but all 2001:<…, in 1752:.) So, if 1674:such that 1638:and every 1550:such that 1510:, the sum 1437:and every 1429:For every 1414:, the sum 1402:For every 1068:for every 1054:such that 825:to be the 774:(that is, 527:Suppose a 346:comparable 277:transitive 237:for every 223:≤ that is 172:Motivation 133:that in a 63:for every 53:set theory 7744:Upper set 7681:Embedding 7617:Antichain 7438:Tolerance 7428:Symmetric 7423:Semiorder 7369:Reflexive 7287:Connected 7035:Supertask 6938:Recursion 6896:decidable 6730:saturated 6708:of models 6631:deductive 6626:axiomatic 6546:Hilbert's 6533:Euclidean 6514:canonical 6437:axiomatic 6369:Signature 6298:Predicate 6187:Extension 6109:Ackermann 6034:Operation 5913:Universal 5903:Recursive 5878:Singleton 5873:Inhabited 5858:Countable 5848:Types of 5832:power set 5802:partition 5719:Predicate 5665:Predicate 5580:Syllogism 5570:Soundness 5543:Inference 5533:Tautology 5435:paradoxes 5279:EMS Press 5215:(2008) . 5064:: 75–76. 4708:↪ 4633:14 August 4480:Jech 2008 4468:Jech 2008 4372:Antichain 4176:in 1940. 4040:◻ 3768:− 3762:∈ 3705:⊂ 3440:∈ 3350:∪ 3275:→ 3189:≤ 3156:∈ 3135:⊂ 3124:∣ 3118:→ 3069:∈ 3058:for each 3043:∈ 3005:→ 2966:⋃ 2786:~ 2731:∪ 2719:~ 2690:≥ 1934:∈ 1886:≥ 1874:∈ 1868:∀ 1859:∈ 970:⋯ 622:vacuously 245:(if both 225:reflexive 7539:Topology 7406:Preorder 7389:Eulerian 7352:Complete 7302:Directed 7292:Covering 7157:Preorder 7116:Category 7111:Glossary 7020:Logicism 7013:timeline 6989:Concrete 6848:Validity 6818:T-schema 6811:Kripke's 6806:Tarski's 6801:semantic 6791:Strength 6740:submodel 6735:spectrum 6703:function 6551:Tarski's 6540:Elements 6527:geometry 6483:Robinson 6404:variable 6389:function 6362:spectrum 6352:Sentence 6308:variable 6251:Language 6204:Relation 6165:Automata 6155:Alphabet 6139:language 5993:-jection 5971:codomain 5957:Function 5918:Universe 5888:Infinite 5792:Relation 5575:Validity 5565:Argument 5463:theorem, 5296:Metamath 4885:24 April 4596:(2015). 4565:(2015). 4526:(2002). 4426:(2003), 4366:See also 4178:Bourbaki 4159:Max Zorn 3890:′ 3775:′ 3732:′ 3701:′ 3342:′ 3131:′ 3114:′ 2893:. Then 2807:. Thus, 2157: : 2113: : 2084: : 2015:ordinals 1825:function 1702:. Thus, 1658:Suppose 1566:. Since 1526:Suppose 1470:Because 719:. Since 497:. Here, 193:—  123:topology 99:Max Zorn 7644:Duality 7622:Cofinal 7610:Related 7589:Fréchet 7466:)  7342:Bounded 7337:Lattice 7310:)  7308:Partial 7176:Results 7147:Lattice 6962:Related 6759:Diagram 6657: ( 6636:Hilbert 6621:Systems 6616:Theorem 6494:of the 6439:systems 6219:Formula 6214:Grammar 6130: ( 6074:General 5787:Forcing 5772:Element 5692:Monadic 5467:paradox 5408:Theorem 5344:General 5281:, 2001 4681:, § 16. 4528:Algebra 4142:History 4058:: take 3488:, then 2772:and so 2705:, then 2244:below. 2214:, then 2062:we set 1740:, then 1690:, then 1278:except 1122:, ..., 1094:, ..., 1043:, ..., 902:, ..., 887:scalars 874:, ..., 707:}. Let 640:, then 542:has an 432:maximal 275:), and 145:has an 7669:Subnet 7649:Filter 7599:Normed 7584:Banach 7550:& 7457:Better 7394:Strict 7384:Graded 7275:topics 7106:Topics 6725:finite 6488:Skolem 6441:  6416:Theory 6384:Symbol 6374:String 6357:atomic 6234:ground 6229:closed 6224:atomic 6180:ground 6143:syntax 6039:binary 5966:domain 5883:Finite 5648:finite 5506:Logics 5465:  5413:Theory 5250:  5227:  5201:  5185:  5010:  4964:  4797:Halmos 4679:Halmos 4606:  4575:  4560:, and 4552:  4534:  4294:Every 3966:is in 2431:is in 2348:is in 2240:or in 1997:< a 1768:– but 1719:proper 1678:is in 1650:is in 1518:is in 1449:is in 1422:is in 1384:. For 1268:ideals 1265:proper 1021:Since 680:has a 573:  485:is an 113:has a 72:subset 36:has a 7659:Ideal 7637:Graph 7433:Total 7411:Total 7297:Dense 6715:Model 6463:Peano 6320:Proof 6160:Arity 6089:Naive 5976:image 5908:Fuzzy 5868:Empty 5817:union 5762:Class 5403:Model 5393:Lemma 5351:Axiom 4860:(PDF) 4628:(PDF) 4428:Trees 4411:Notes 4272:basis 4163:axiom 3788:. As 3429:when 3244:. If 2848:Lemma 2455:Then 2257:Lemma 2248:Proof 2200:poset 2198:is a 2189:Lemma 2161:< 2117:< 2088:< 1986:< 1979:< 1972:< 1717:is a 1682:. If 1458:#1 - 1356:Take 1313:. If 1250:unity 1248:with 1177:is a 1076:. As 827:union 821:Take 751:(see 735:, so 682:basis 646:every 536:chain 450:with 413:chain 325:with 299:then 143:field 115:basis 93:) by 87:lemma 65:chain 34:graph 7250:list 6838:Type 6641:list 6445:list 6422:list 6411:Term 6345:rank 6239:open 6133:list 5945:Maps 5850:sets 5709:Free 5679:list 5429:list 5356:list 5248:ISBN 5225:ISBN 5199:ISBN 5183:ISBN 5008:ISBN 4962:ISBN 4887:2013 4841:help 4822:help 4803:help 4685:help 4635:2022 4604:ISBN 4573:ISBN 4550:ISBN 4532:ISBN 4146:The 3997:< 3986:and 3911:and 3473:< 2853:Let 2262:Let 2032:The 1744:1 = 1594:and 1558:and 1530:and 1259:Let 1243:ring 885:and 458:and 415:(in 368:nor 356:and 317:and 289:and 279:(if 255:and 190:you. 135:ring 85:The 7664:Net 7464:Pre 6525:of 6507:of 6455:of 5987:Sur 5961:Map 5768:Ur- 5750:Set 5294:at 5162:doi 5113:doi 5066:doi 5035:doi 5000:doi 4954:doi 4914:doi 4874:doi 4662:doi 4362:". 4306:of 4180:'s 4118:is 3669:in 2929:.) 2639:in 2559:in 2391:in 2194:If 2050:in 1999:ω+1 1958:). 1578:or 1372:in 1353:). 1321:in 1309:in 1270:in 1205:∪ { 1181:of 1158:of 1147:). 841:in 810:of 794:in 770:in 731:of 703:≠ { 691:= { 687:If 546:in 538:in 489:of 481:of 446:in 399:to 321:of 241:), 214:set 121:in 105:in 7766:: 6911:NP 6535:: 6529:: 6459:: 6136:), 5991:Bi 5983:In 5277:, 5271:, 5246:. 5242:. 5223:. 5177:, 5156:. 5152:. 5109:26 5107:, 5093:^ 5062:37 5060:. 5056:. 5006:. 4960:, 4910:41 4908:. 4904:. 4862:. 4658:98 4656:. 4652:. 4542:, 4220:ZF 4138:. 4032:. 2963::= 2833:. 2226:. 2153:∈ 2149:({ 2145:= 2137:∈ 2129:⊆ 2075:({ 2071:= 1787:. 1776:. 1710:. 1692:rx 1686:∈ 1670:∈ 1648:rx 1642:∈ 1634:∈ 1626:. 1618:+ 1606:+ 1586:. 1582:⊆ 1574:⊆ 1546:∈ 1542:, 1514:+ 1506:∈ 1502:, 1494:. 1447:rx 1441:∈ 1433:∈ 1418:+ 1410:∈ 1406:, 1337:⊆ 1302:. 1256:. 1233:. 1193:∈ 1162:. 1115:, 1087:, 1061:∈ 1050:∈ 1036:, 895:, 881:∈ 867:, 853:. 818:. 763:. 684:. 558:. 462:≤ 454:≠ 372:≤ 364:≤ 333:, 329:≤ 304:≤ 294:≤ 284:≤ 270:= 260:≤ 250:≤ 232:≤ 212:A 149:. 117:, 82:. 74:) 7462:( 7459:) 7455:( 7306:( 7253:) 7087:e 7080:t 7073:v 6991:/ 6906:P 6661:) 6447:) 6443:( 6340:∀ 6335:! 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Index

Zorns Lemma

graph
spanning tree
set theory
partially ordered set
upper bounds
chain
totally ordered
subset
necessarily
maximal element
lemma
axiom of choice
Kazimierz Kuratowski
Max Zorn
Hahn–Banach theorem
functional analysis
vector space
basis
Tychonoff's theorem
topology
compact spaces
abstract algebra
ring
maximal ideal
field
algebraic closure
well-ordering theorem
axiom of choice

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