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Galois connection

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4616:. However, this terminology is avoided for Galois connections, since there was a time when posets were transformed into categories in a dual fashion, i.e. with morphisms pointing in the opposite direction. This led to a complementary notation concerning left and right adjoints, which today is ambiguous. 4337:
In this situation, an important feature of Galois connections is that one adjoint uniquely determines the other. Hence one can strengthen the above statement to guarantee that any supremum-preserving map between complete lattices is the lower adjoint of a unique Galois connection. The main property
5036:, in: Proceedings of the 1991 Summer Conference on General Topology and Applications in Honor of Mary Ellen Rudin and Her Work, Annals of the New York Academy of Sciences, Vol. 704, 1993, pp. 103–125. (Freely available online in various file formats 4565:
is also a Galois connection. When considering categories of complete lattices, this can be simplified to considering just mappings preserving all suprema (or, alternatively, infima). Mapping complete lattices to their duals, these categories display auto
1903: 3483:
antitone Galois connections between power sets arise in this way. This follows from the "Basic Theorem on Concept Lattices". Theory and applications of Galois connections arising from binary relations are studied in
3109: 242:. Mnemonically, the upper/lower terminology refers to where the function application appears relative to ≀. The term "adjoint" refers to the fact that monotone Galois connections are special cases of pairs of 1402: 3274: 1541: 1478: 1346: 1124:
truncating a real number to the greatest integer less than or equal to it. The embedding of integers is customarily done implicitly, but to show the Galois connection we make it explicit. So let
3749:. Thus monotonicity does not have to be included in the definition explicitly. However, mentioning monotonicity helps to avoid confusion about the two alternative notions of Galois connections. 2060: 1991: 1240: 1158: 4255:. In this way, closure operators and Galois connections are seen to be closely related, each specifying an instance of the other. Similar conclusions hold true for kernel operators. 1284: 1204: 1789: 4430:. The existence of a certain Galois connection now implies the existence of the respective least or greatest elements, no matter whether the corresponding posets satisfy any 3495:
in its primitive version incorporates both the monotone and antitone Galois connections to furnish its upper and lower bounds of nodes for the concept lattice, respectively.
1938: 1110: 1081: 4949: 62:; this article presents the common case of posets. The literature contains two closely related notions of "Galois connection". In this article, we will refer to them as 898: 863: 1043: 3537:
is the lower adjoint as introduced above. Some helpful and instructive basic properties can be obtained immediately. By the defining property of Galois connections,
1005: 970: 938: 3488:. That field uses Galois connections for mathematical data analysis. Many algorithms for Galois connections can be found in the respective literature, e.g., in. 1425: 1753:
can be characterized by the existence of suitable adjoints. These considerations give some impression of the ubiquity of Galois connections in order theory.
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between the involved posets, but every Galois connection gives rise to an isomorphism of certain sub-posets, as will be explained below. The term
4907: 3326:(not necessarily a polynomial ring), there is an antitone Galois connection between radical ideals in the ring and Zariski closed subsets of the 5037: 3020: 1354: 556:. However the original notion in Galois theory is slightly different. In this alternative definition, a Galois connection is a pair of 4082:(respectively residual mapping). Therefore, the notion of residuated mapping and monotone Galois connection are essentially the same. 3157: 1493: 816:. All of the below statements on Galois connections can thus easily be converted into statements about antitone Galois connections. 5059: 4656:
definition. One can also define Galois connections as a pair of monotone functions that satisfy the laxer condition that for all
4930:"Abstract Interpretation: A Unified Lattice Model for Static Analysis of Programs by Construction or Approximation of Fixpoints" 5043:, it presents many examples and results, as well as notes on the different notations and definitions that arose in this area.) 4434:. Thus, when one upper adjoint of a Galois connection is given, the other upper adjoint can be defined via this same property. 4327: 1430: 5101: 4979: 4929: 4858: 1289: 791:
The implications of the two definitions of Galois connections are very similar, since an antitone Galois connection between
4838: 36: 2073:, one can establish that doubly transitive actions have no blocks other than the trivial ones (singletons or the whole of 5014: 1999: 1962: 5086: 5068: 4759: 1209: 1127: 5170: 1742:. The least and greatest elements of a partial order are given by lower and upper adjoints to the unique function 4311: 3739:
preserves the order of any two elements, i.e. it is monotone. Again, a similar reasoning yields monotonicity of
1898:{\displaystyle {\mathcal {B}}=\{B\subseteq X:x\in B;\forall g\in G,gB=B\ \mathrm {or} \ gB\cap B=\emptyset \},} 4177:. Nuclei induce frame homomorphisms; a subset of a locale is called a sublocale if it is given by a nucleus. 2776: 1245: 1163: 4489:
Galois connections also provide an interesting class of mappings between posets which can be used to obtain
4586:
Every partially ordered set can be viewed as a category in a natural way: there is a unique morphism from
4608:
between two categories that arise from partially ordered sets. In this context, the upper adjoint is the
4431: 2505: 1722: 1652: 4105:
is monotone (being the composite of monotone functions), inflationary, and idempotent. This states that
3348: 3327: 3011: 5175: 3305: 4871: 1725:. Roughly speaking, it turns out that the usual functions ∨ and ∧ are lower and upper adjoints to the 641:
in this version erases the distinction between upper and lower, and the two functions are then called
35:(posets). Galois connections find applications in various mathematical theories. They generalize the 4567: 4330:
states that the converse implication is also valid in certain cases: especially, any mapping between
1919: 4575: 1768: 1090: 1061: 261:
An essential property of a Galois connection is that an upper/lower adjoint of a Galois connection
92:(or dual order isomorphism, depending on whether we take monotone or antitone Galois connections). 1949: 5003:
The following books and survey articles include Galois connections using the monotone definition:
4625: 3492: 3485: 5160: 4490: 3588: 2224:, both ordered by inclusion βŠ†. There is a further adjoint pair in this situation: for a subset 2109: 1643:
being the lower adjoint. A similar Galois connection whose lower adjoint is given by the meet (
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of posets. Especially, it is possible to compose Galois connections: given Galois connections
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that induce adjoint mappings in the other direction are the morphisms usually considered for
4326:. From these properties, one can also conclude monotonicity of the adjoints immediately. The 2817: 1010: 122: 32: 2283:
is the upper adjoint, while in the second Galois connection it serves as the lower adjoint.
975: 4629: 4319: 3115: 943: 911: 411: 742:
are the associated closure operators; they are monotone idempotent maps with the property
8: 4570:, that are quite fundamental for obtaining other duality theorems. More special kinds of 3309: 3144: 2977: 2810: 2291: 2121: 4808: 4090:
The above findings can be summarized as follows: for a Galois connection, the composite
3924:
This shows the desired equality. Furthermore, we can use this property to conclude that
1427:
is restricted to the integers. The well-known properties of the floor function, such as
5140: 4899: 4737: 4147: 4079: 3331: 2959: 2655: 2442: 2345: 2082: 2066: 1702: 1410: 4624:
Galois connections may be used to describe many forms of abstraction in the theory of
3343:
More generally, there is an antitone Galois connection between ideals in the ring and
48: 5097: 5082: 5064: 5054: 4959: 4903: 4891: 4854: 4834: 4765: 4755: 2747: 2740: 2560: 2427: 1556: 901: 514: 130: 89: 74: 5021:
Gerhard Gierz, Karl H. Hofmann, Klaus Keimel, Jimmie D. Lawson, Michael W. Mislove,
1721:
Further interesting examples for Galois connections are described in the article on
5132: 5107: 5009: 4883: 4747: 4605: 4331: 4180: 4121: 3320: 3297: 1750: 1484: 900:
each other's inverse, forms a (trivial) Galois connection, as follows. Because the
428: 386: 243: 59: 4481:, contains a greatest element. Again, this can be dualized for the upper adjoint. 4800: 4733: 3368: 2988: 2623: 2493: 2392: 2295: 1648: 549: 247: 44: 4947: 4751: 4652:. It is only explicit in the definition to distinguish it from the alternative 4446: 3711:. Applying the basic property of Galois connections, one can now conclude that 2970: 2764: 2737: 2341: 2287: 1121: 197: 55: 5118: 5040: 4887: 4142:
is monotone, deflationary, and idempotent. Such mappings are sometimes called
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For a counterexample for the false theorem in Sect.7 (p.243 top right), see:
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Monotonicity follows from the following condition. See the discussion of the
4233: 2457: 2167: 1576: 905: 553: 4872:"A general theory of concept lattice with tractable implication exploration" 4807:. The notation is different nowadays; an easier introduction by Peter Smith 2838:. This yields an antitone Galois connection between the set of subspaces of 548:
The above definition is common in many applications today, and prominent in
5092:
Nikolaos Galatos, Peter Jipsen, Tomasz Kowalski, and Hiroakira Ono (2007),
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form a monotone Galois connection, with semantics being the upper adjoint.
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The dual orderings give another monotone Galois connection, now with the
1113: 645:
rather than adjoints. Each polarity uniquely determines the other, since
20: 4334:
that preserves all suprema is the lower adjoint of a Galois connection.
4310:
Another important property of Galois connections is that lower adjoints
5144: 4820:
Birkhoff, 1st edition (1940): Β§32, 3rd edition (1967): Ch. V, Β§7 and Β§8
4251:, that maps each closed element to itself, considered as an element of 4208: 4056: 2963: 2876: 529: 446: 2512:
the power set of the set of all mathematical structures. For a theory
3344: 2372: 2070: 1568: 1117: 830: 382: 82: 5136: 1480:
can be derived by elementary reasoning from this Galois connection.
4742: 4571: 4315: 3104:{\displaystyle V(S)=\{x\in K^{n}:f(x)=0{\mbox{ for all }}f\in S\},} 2384: 1941: 40: 5032:
Marcel ErnΓ©, JΓΌrgen Koslowski, Austin Melton, George E. Strecker,
2746:, there is an antitone Galois connection between subgroups of the 2563:, this is the set of sentences that are true in all structures in 250:
as discussed further below. Other terminology encountered here is
5094:
Residuated Lattices. An Algebraic Glimpse at Substructural Logics
4987:
Proc. 6th ACM Symp. on Principles of Programming Languages (POPL)
4948:
Jochen Burghardt; Florian KammΓΌller; Jeff W. Sanders (Dec 2000).
4323: 4305: 4288:) are mapped to elements within the range of the kernel operator 2388: 1644: 1397:{\displaystyle n\leq x~\Leftrightarrow ~n\leq \lfloor x\rfloor .} 1084: 445:, known as the associated kernel operator. Both are monotone and 2939:
This gives an antitone Galois connection between the subsets of
904:
is reflexive, transitive and antisymmetric, it is, trivially, a
4968:(However the original article only considers complete lattices) 4062:
It can be shown (see Blyth or ErnΓ© for proofs) that a function
3269:{\displaystyle I(U)=\{f\in K:f(x)=0{\mbox{ for all }}x\in U\}.} 2842:
and itself, ordered by inclusion; both polarities are equal to
1580: 1536:{\displaystyle x\leq n~\Leftrightarrow ~\lceil x\rceil \leq n.} 4791:
See Alperin, Bell, Groups and Representations (GTM 162), p. 32
3752:
Another basic property of Galois connections is the fact that
3468:
yield an antitone Galois connection between the power sets of
4604:. A monotone Galois connection is then nothing but a pair of 3503:
In the following, we consider a (monotone) Galois connection
2531: 4619: 3621:. These properties can be described by saying the composite 16:
Particular correspondence between two partially ordered sets
5048:
Some publications using the original (antitone) definition:
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The above considerations also show that closed elements of
4085: 2271:
form a monotone Galois connection between the power set of
2216:
form a monotone Galois connection between the power set of
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is inflationary as shown above. On the other hand, since
2612:
The motivating example comes from Galois theory: suppose
1546: 4811:, which also attribute the concept to the article cited. 1473:{\displaystyle \lfloor x+n\rfloor =\lfloor x\rfloor +n,} 4191:
gives rise to the Galois connection with lower adjoint
4070:
is a lower (respectively upper) adjoint if and only if
3355:
Connections on power sets arising from binary relations
2805:
Linear algebra: annihilators and orthogonal complements
2555:
be the minimum of the axiomatizations that approximate
31:
is a particular correspondence (typically) between two
4338:
to derive this uniqueness is the following: For every
3245: 3080: 2966:
and their zero sets is an antitone Galois connection.
2731: 2077:): this follows from the stabilizers being maximal in 1341:{\displaystyle F(n)\leq x~\Leftrightarrow ~n\leq G(x)} 1116:, each with its usual ordering, is given by the usual 4732:. Lecture Notes in Computer Science. Vol. 2962. 4730:
Semirings for Soft Constraint Solving and Programming
3160: 3023: 2472:
form a monotone Galois connection between subsets of
2002: 1965: 1922: 1792: 1496: 1433: 1413: 1357: 1292: 1248: 1212: 1166: 1130: 1093: 1064: 1013: 978: 946: 914: 871: 839: 4939:
ACM Symposium on Principles of Programming Languages
509:
is a Galois connection in which the kernel operator
4831:
Formal Concept Analysis -- Mathematical Foundations
2508:(axiomatizations) reverse ordered by strength, and 4980:"Systematic Design of Program Analysis Frameworks" 4484: 3587:. By a similar reasoning (or just by applying the 3268: 3103: 2054: 1985: 1932: 1897: 1535: 1472: 1419: 1396: 1340: 1278: 1234: 1198: 1152: 1104: 1075: 1037: 999: 964: 932: 892: 857: 73:A Galois connection is rather weak compared to an 5124:Transactions of the American Mathematical Society 3308:, then the closure on the polynomial ring is the 2055:{\displaystyle B\mapsto H_{B}=\{g\in G:gx\in B\}} 5152: 4803:, Adjointness in foundations, Dialectica, 1969, 4581: 1986:{\displaystyle {\mathcal {B}}\to {\mathcal {G}}} 1120:function of the integers into the reals and the 4322:. Dually, upper adjoints preserve all existing 100: 4870:Liaw, Tsong-Ming; Lin, Simon C. (2020-10-12). 4306:Existence and uniqueness of Galois connections 2694:to be the field consisting of all elements of 2682:, ordered by inclusion βŠ†. For such a subgroup 2602: 2537: ; for a set of mathematical structures 2530:be the set of all structures that satisfy the 1235:{\displaystyle G:\mathbb {R} \to \mathbb {Z} } 1153:{\displaystyle F:\mathbb {Z} \to \mathbb {R} } 1048: 258:) for the lower (respectively upper) adjoint. 1655:, where the two mappings can be described by 799:is just a monotone Galois connection between 543: 402:Given a Galois connection with lower adjoint 3260: 3176: 3095: 3039: 2049: 2022: 1889: 1803: 1709:" is the upper adjoint of "conjunction with 1521: 1515: 1458: 1452: 1446: 1434: 1388: 1382: 1270: 1264: 5114:, Amer. Math. Soc. Coll. Pub., Vol 25, 1940 2312:, and the closure operator on subgroups of 1756: 54:A Galois connection can also be defined on 4978:Patrick Cousot; Radhia Cousot (Jan 1979). 4928:Patrick Cousot; Radhia Cousot (Jan 1977). 4727: 4437:On the other hand, some monotone function 2088: 1639:, form a monotone Galois connection, with 5079:Lattices and Ordered Algebraic Structures 4741: 4620:Applications in the theory of programming 1228: 1220: 1189: 1146: 1138: 1095: 1066: 47:, discovered by the French mathematician 5060:Categories for the Working Mathematician 5053: 4328:adjoint functor theorem for order theory 4086:Closure operators and Galois connections 4869: 2698:that are held fixed by all elements of 2487: 1279:{\displaystyle G(x)=\lfloor x\rfloor .} 1199:{\displaystyle F(n)=n\in \mathbb {R} ,} 5153: 1547:Power set; implication and conjunction 2953: 1058:A monotone Galois connection between 129:between these posets consists of two 3287:form an antitone Galois connection. 3010:is a set of polynomials, define the 2875:, consisting of all elements of the 2728:form an antitone Galois connection. 2480:, if both are ordered by inclusion. 1551:For an order-theoretic example, let 1160:denote the embedding function, with 37:fundamental theorem of Galois theory 5117: 5029:, Cambridge University Press, 2003. 5018:, Cambridge University Press, 2002. 4954:(Technical report). Vol. 122. 3689:. Then using the above one obtains 2732:Algebraic topology: covering spaces 2331: 2290:between algebraic objects (such as 1651:. Especially, it is present in any 1407:This is valid because the variable 13: 5015:Introduction to Lattices and Order 4863: 3589:duality principle for order theory 2279:. In the first Galois connection, 1978: 1968: 1925: 1886: 1864: 1861: 1830: 1795: 560:, i.e. order-reversing, functions 14: 5187: 2987:be the set of all subsets of the 2797:, there is a covering space with 2294:), this connection is called the 1053: 373:A consequence of this is that if 39:about the correspondence between 4951:Isomorphism of Galois Embeddings 4199:being just the corestriction of 2996:ordered by inclusion βŠ†, and let 2607: 1647:) operation can be found in any 5027:Continuous Lattices and Domains 4971: 4921: 4910:from the original on 2020-05-28 4649: 4612:while the lower adjoint is the 4485:Galois connections as morphisms 3476:, both ordered by inclusion βŠ†. 2962:, the relation between sets of 2630:be the set of all subfields of 1242:denotes the floor function, so 5034:A primer on Galois connections 4989:. ACM Press. pp. 269–282. 4843: 4823: 4814: 4794: 4785: 4776: 4721: 4712: 4642: 3235: 3229: 3220: 3188: 3170: 3164: 3070: 3064: 3033: 3027: 2864:we can define its annihilator 2336:Pick some mathematical object 2006: 1973: 1933:{\displaystyle {\mathcal {G}}} 1509: 1370: 1335: 1329: 1314: 1302: 1296: 1258: 1252: 1224: 1176: 1170: 1142: 1029: 1023: 988: 982: 972:partially ordered sets. Since 959: 947: 927: 915: 881: 849: 95: 1: 5121:(1944), "Galois Connexions", 5063:(Second ed.). Springer. 4997: 4582:Connection to category theory 3880:is monotonic, one finds that 3498: 3000:be the set of all subsets of 2777:semi-locally simply connected 2638:, ordered by inclusion βŠ†. If 2449:, and take as "subobjects of 1105:{\displaystyle \mathbb {R} ,} 1076:{\displaystyle \mathbb {Z} ,} 1045:we have a Galois connection. 824: 64:(monotone) Galois connections 4876:Theoretical Computer Science 4849:Ganter, B. and Obiedkov, S. 4728:Bistarelli, Stefano (2004). 3147:of polynomials vanishing on 2904:, we define its annihilator 2893:. Similarly, given a subset 101:(Monotone) Galois connection 81:is sometimes used to mean a 7: 4752:10.1007/978-3-540-25925-1_8 4211:mapping the closure system 3731:. But this just shows that 3006:ordered by inclusion βŠ†. If 2670:be the set of subgroups of 2642:is such a subfield, write 2603:Antitone Galois connections 1716: 1049:Monotone Galois connections 819: 532:the set of closed elements 525:is an order isomorphism of 68:antitone Galois connections 10: 5192: 3421:Similarly, for any subset 2801:as its fundamental group. 2779:, then for every subgroup 2591:: the "semantics functor" 2492:A very general comment of 544:Antitone Galois connection 427:, known as the associated 127:monotone Galois connection 4888:10.1016/j.tcs.2020.05.014 4829:Ganter, B. and Wille, R. 3382:is given. For any subset 3367:are arbitrary sets and a 2595:and the "syntax functor" 2418:be the underlying set of 1959:Then, the correspondence 1705:terms: "implication from 893:{\displaystyle g:Y\to X,} 4635: 4318:that exist within their 3319:More generally, given a 2567:). We can then say that 2344:, for instance a group, 2302:connect to subgroups of 2085:for further discussion. 2069:Galois connection. As a 1757:Transitive group actions 858:{\displaystyle f:X\to Y} 5171:Abstract interpretation 4626:abstract interpretation 4432:completeness properties 4183:, any closure operator 3870:is deflationary, while 3797:. Clearly we find that 3493:general concept lattice 3486:formal concept analysis 2089:Image and inverse image 2083:Doubly transitive group 1723:completeness properties 1038:{\displaystyle x=g(y),} 833:of a pair of functions 691:is the largest element 659:is the largest element 331:is the largest element 4851:Conceptual Exploration 4809:in these lecture notes 3312:of ideal generated by 3296:is the closure in the 3270: 3118:of the polynomials in 3105: 2484:is the lower adjoint. 2352:, etc. For any subset 2112:, then for any subset 2056: 1987: 1934: 1899: 1537: 1474: 1421: 1398: 1342: 1280: 1236: 1200: 1154: 1106: 1077: 1039: 1001: 1000:{\displaystyle f(x)=y} 966: 934: 894: 859: 410:, we can consider the 265:determines the other: 123:partially ordered sets 33:partially ordered sets 4630:programming languages 4449:each set of the form 4358:is the least element 4232:is then given by the 4222:). The upper adjoint 3347:of the corresponding 3271: 3106: 2818:orthogonal complement 2736:Analogously, given a 2504:to be the set of all 2275:and the power set of 2220:and the power set of 2057: 1988: 1935: 1900: 1538: 1475: 1422: 1399: 1343: 1281: 1237: 1201: 1155: 1107: 1078: 1040: 1002: 967: 965:{\displaystyle (Y,=)} 935: 933:{\displaystyle (X,=)} 895: 860: 279:is the least element 79:Galois correspondence 5077:Thomas Scott Blyth, 4384:. Dually, for every 4146:. In the context of 3306:algebraically closed 3158: 3021: 2771:. In particular, if 2498:syntax and semantics 2488:Syntax and semantics 2422:. (We can even take 2399:. For any subobject 2000: 1963: 1920: 1790: 1775:and pick some point 1749:Going further, even 1494: 1431: 1411: 1355: 1290: 1246: 1210: 1164: 1128: 1091: 1062: 1011: 976: 944: 912: 869: 837: 164:, such that for all 88:; this is simply an 5010:Hilary A. Priestley 5008:Brian A. Davey and 4943:. pp. 238–252. 4853:, Springer (2016), 4833:, Springer (1999), 4445:is a lower adjoint 3438: ) = {  3399: ) = {  3300:, and if the field 3247: for all  3082: for all  2943:and the subsets of 2913: ) = {  2811:inner product space 2763:and path-connected 2656:field automorphisms 2158:and for any subset 1348:then translates to 588:between two posets 389:of the other, i.e. 218:In this situation, 5081:, Springer, 2005, 5057:(September 1998). 5055:Mac Lane, Saunders 4302:, and vice versa. 4148:frames and locales 4080:residuated mapping 3591:), one finds that 3479:Up to isomorphism 3266: 3249: 3114:the set of common 3101: 3084: 2960:algebraic geometry 2954:Algebraic geometry 2816:, we can form the 2587:logically entails 2500:are adjoint: take 2476:and subobjects of 2178: ) =   2132: ) =   2081:in that case. See 2052: 1983: 1930: 1895: 1533: 1470: 1417: 1394: 1338: 1276: 1232: 1196: 1150: 1102: 1073: 1035: 997: 962: 930: 890: 855: 406:and upper adjoint 5176:Closure operators 5102:978-0-444-52141-5 4859:978-3-662-49290-1 4332:complete lattices 3557:is equivalent to 3248: 3083: 2748:fundamental group 2741:topological space 2654:for the group of 2561:first-order logic 2428:topological space 2286:In the case of a 1870: 1859: 1751:complete lattices 1514: 1508: 1420:{\displaystyle n} 1375: 1369: 1319: 1313: 902:equality relation 714:The compositions 385:then each is the 90:order isomorphism 86:Galois connection 75:order isomorphism 29:Galois connection 5183: 5147: 5108:Garrett Birkhoff 5074: 4991: 4990: 4984: 4975: 4969: 4967: 4958:. p. 9-14. 4944: 4934: 4925: 4919: 4918: 4916: 4915: 4867: 4861: 4847: 4841: 4839:978-3-540-627715 4827: 4821: 4818: 4812: 4798: 4792: 4789: 4783: 4780: 4774: 4773: 4745: 4725: 4719: 4716: 4710: 4708: 4690: 4686: 4682: 4663: 4659: 4646: 4606:adjoint functors 4603: 4564: 4539:, the composite 4538: 4534: 4530: 4515: 4511: 4507: 4480: 4476: 4472: 4444: 4429: 4414: 4410: 4407:is the greatest 4406: 4391: 4387: 4383: 4365: 4361: 4357: 4345: 4341: 4301: 4287: 4265: 4261: 4254: 4250: 4246: 4231: 4221: 4206: 4203:to the image of 4202: 4198: 4190: 4186: 4176: 4164: 4150:, the composite 4144:kernel operators 4141: 4127: 4122:closure operator 4119: 4104: 4077: 4069: 4054: 4039: 4022: 3971: 3919: 3879: 3869: 3855: 3836: 3796: 3792: 3788: 3748: 3738: 3730: 3710: 3688: 3678: 3653: 3634: 3620: 3616: 3612: 3586: 3582: 3578: 3556: 3536: 3521: 3475: 3471: 3467: 3463: 3459: 3428: 3424: 3420: 3389: 3385: 3381: 3377: 3373: 3366: 3362: 3339: 3325: 3321:commutative ring 3315: 3303: 3298:Zariski topology 3295: 3282: 3275: 3273: 3272: 3267: 3250: 3246: 3219: 3218: 3200: 3199: 3150: 3142: 3131: 3125: 3121: 3110: 3108: 3107: 3102: 3085: 3081: 3057: 3056: 3009: 3005: 2999: 2995: 2986: 2982: 2975: 2949: 2942: 2938: 2903: 2896: 2892: 2888: 2884: 2874: 2863: 2859: 2855: 2845: 2841: 2837: 2833: 2830:of any subspace 2829: 2815: 2800: 2796: 2782: 2774: 2770: 2762: 2745: 2727: 2716: 2702:. Then the maps 2701: 2697: 2693: 2685: 2681: 2669: 2665: 2661: 2653: 2641: 2637: 2633: 2629: 2621: 2598: 2594: 2590: 2586: 2578: 2570: 2566: 2558: 2554: 2546: 2536: 2529: 2521: 2511: 2506:logical theories 2503: 2483: 2479: 2475: 2471: 2467: 2463: 2455: 2452: 2448: 2440: 2425: 2421: 2417: 2406: 2402: 2398: 2382: 2378: 2371:be the smallest 2370: 2359: 2355: 2339: 2332:Span and closure 2327: 2322: 2315: 2311: 2301: 2282: 2278: 2274: 2270: 2266: 2262: 2231: 2227: 2223: 2219: 2215: 2211: 2207: 2166:we can form the 2165: 2161: 2157: 2120:we can form the 2119: 2115: 2107: 2080: 2076: 2061: 2059: 2058: 2053: 2018: 2017: 1992: 1990: 1989: 1984: 1982: 1981: 1972: 1971: 1955: 1947: 1939: 1937: 1936: 1931: 1929: 1928: 1915: 1904: 1902: 1901: 1896: 1868: 1867: 1857: 1799: 1798: 1782: 1778: 1774: 1764: 1748: 1741: 1712: 1708: 1700: 1673: 1642: 1638: 1615: 1597: 1593: 1590:. Then the maps 1589: 1585: 1574: 1566: 1562: 1554: 1542: 1540: 1539: 1534: 1512: 1506: 1485:ceiling function 1479: 1477: 1476: 1471: 1426: 1424: 1423: 1418: 1403: 1401: 1400: 1395: 1373: 1367: 1347: 1345: 1344: 1339: 1317: 1311: 1286:The equivalence 1285: 1283: 1282: 1277: 1241: 1239: 1238: 1233: 1231: 1223: 1205: 1203: 1202: 1197: 1192: 1159: 1157: 1156: 1151: 1149: 1141: 1111: 1109: 1108: 1103: 1098: 1082: 1080: 1079: 1074: 1069: 1044: 1042: 1041: 1036: 1006: 1004: 1003: 998: 971: 969: 968: 963: 939: 937: 936: 931: 899: 897: 896: 891: 864: 862: 861: 856: 815: 811: 802: 798: 794: 787: 783: 779: 764: 760: 756: 741: 727: 709: 694: 690: 677: 662: 658: 640: 636: 633:The symmetry of 628: 613: 595: 591: 587: 573: 539: 535: 528: 524: 520: 512: 508: 504: 499:Galois insertion 493: 489: 485: 471: 467: 463: 444: 429:closure operator 426: 409: 405: 398: 380: 376: 368: 363: 362: 361: 356: 345: 344: 343: 342: 337: 330: 317: 315: 314: 313: 308: 293: 292: 291: 290: 285: 278: 244:adjoint functors 233: 229: 221: 213: 196: 179: 175: 171: 167: 163: 149: 120: 112: 23:, especially in 5191: 5190: 5186: 5185: 5184: 5182: 5181: 5180: 5151: 5150: 5137:10.2307/1990305 5071: 5000: 4995: 4994: 4982: 4976: 4972: 4945: 4932: 4926: 4922: 4913: 4911: 4868: 4864: 4848: 4844: 4828: 4824: 4819: 4815: 4801:William Lawvere 4799: 4795: 4790: 4786: 4782:Galatos, p. 145 4781: 4777: 4762: 4736:. p. 102. 4734:Springer-Verlag 4726: 4722: 4717: 4713: 4692: 4688: 4684: 4665: 4661: 4657: 4647: 4643: 4638: 4622: 4595: 4594:if and only if 4584: 4562: 4555: 4549: ,   4540: 4536: 4532: 4528: 4517: 4513: 4509: 4508:between posets 4505: 4499: ,   4494: 4487: 4478: 4474: 4450: 4438: 4416: 4412: 4408: 4400: 4393: 4389: 4385: 4377: 4367: 4363: 4359: 4347: 4343: 4339: 4308: 4300: 4289: 4274: 4267: 4263: 4259: 4252: 4248: 4237: 4230: 4223: 4212: 4204: 4200: 4192: 4188: 4184: 4170: 4158: 4151: 4140: 4129: 4125: 4113: 4106: 4098: 4091: 4088: 4071: 4063: 4048: 4041: 4038: 4027: 4012: 3997: 3986: 3979: 3965: 3950: 3939: 3928: 3913: 3902: 3891: 3884: 3878: 3871: 3868: 3857: 3849: 3842: 3830: 3819: 3808: 3801: 3794: 3790: 3782: 3771: 3760: 3753: 3747: 3740: 3732: 3712: 3700: 3690: 3680: 3666: 3647: 3640: 3633: 3622: 3618: 3614: 3603: 3592: 3584: 3580: 3568: 3558: 3538: 3523: 3519: 3513: ,   3504: 3501: 3473: 3469: 3465: 3461: 3430: 3426: 3422: 3391: 3387: 3383: 3379: 3375: 3371: 3369:binary relation 3364: 3360: 3357: 3330: 3323: 3313: 3301: 3291: 3290:The closure on 3280: 3244: 3214: 3210: 3195: 3191: 3159: 3156: 3155: 3148: 3133: 3127: 3126:is a subset of 3123: 3119: 3079: 3052: 3048: 3022: 3019: 3018: 3007: 3001: 2997: 2991: 2989:polynomial ring 2984: 2980: 2973: 2956: 2944: 2940: 2905: 2898: 2894: 2890: 2889:that vanish on 2886: 2879: 2865: 2861: 2857: 2853: 2843: 2839: 2835: 2831: 2820: 2813: 2807: 2798: 2790: 2784: 2780: 2772: 2768: 2765:covering spaces 2756: 2750: 2743: 2734: 2718: 2703: 2699: 2695: 2687: 2683: 2671: 2667: 2663: 2659: 2643: 2639: 2635: 2631: 2627: 2624:field extension 2613: 2610: 2605: 2596: 2592: 2588: 2580: 2579:if and only if 2572: 2571:is a subset of 2568: 2564: 2556: 2548: 2538: 2534: 2523: 2513: 2509: 2501: 2494:William Lawvere 2490: 2481: 2477: 2473: 2469: 2465: 2461: 2453: 2450: 2446: 2431: 2423: 2419: 2408: 2404: 2400: 2396: 2380: 2376: 2361: 2357: 2353: 2337: 2334: 2318: 2317: 2313: 2303: 2299: 2298:: subgroups of 2296:lattice theorem 2280: 2276: 2272: 2268: 2264: 2233: 2229: 2225: 2221: 2217: 2213: 2209: 2170: 2163: 2159: 2124: 2117: 2113: 2094: 2091: 2078: 2074: 2065:is a monotone, 2013: 2009: 2001: 1998: 1997: 1977: 1976: 1967: 1966: 1964: 1961: 1960: 1953: 1948:containing the 1945: 1940:consist of the 1924: 1923: 1921: 1918: 1917: 1916:. Further, let 1913: 1860: 1794: 1793: 1791: 1788: 1787: 1780: 1776: 1772: 1762: 1759: 1743: 1729: 1719: 1710: 1706: 1675: 1656: 1653:Boolean algebra 1649:Heyting algebra 1640: 1633: \  1617: 1599: 1595: 1591: 1587: 1583: 1579:. Pick a fixed 1572: 1564: 1560: 1552: 1549: 1495: 1492: 1491: 1432: 1429: 1428: 1412: 1409: 1408: 1356: 1353: 1352: 1291: 1288: 1287: 1247: 1244: 1243: 1227: 1219: 1211: 1208: 1207: 1188: 1165: 1162: 1161: 1145: 1137: 1129: 1126: 1125: 1094: 1092: 1089: 1088: 1065: 1063: 1060: 1059: 1056: 1051: 1012: 1009: 1008: 1007:if and only if 977: 974: 973: 945: 942: 941: 913: 910: 909: 870: 867: 866: 838: 835: 834: 827: 822: 813: 807: 800: 796: 792: 785: 781: 766: 762: 758: 743: 729: 715: 696: 692: 681: 664: 660: 649: 638: 634: 615: 614:if and only if 600: 593: 589: 575: 561: 546: 537: 533: 526: 522: 518: 510: 506: 502: 491: 487: 473: 469: 465: 450: 432: 414: 407: 403: 390: 378: 374: 357: 354: 353: 352: 347: 338: 335: 334: 333: 332: 321: 309: 306: 305: 304: 295: 286: 283: 282: 281: 280: 269: 248:category theory 231: 227: 219: 200: 184: 177: 173: 169: 165: 151: 137: 114: 106: 103: 98: 56:preordered sets 49:Γ‰variste Galois 17: 12: 11: 5: 5189: 5179: 5178: 5173: 5168: 5163: 5149: 5148: 5131:(3): 493–513, 5115: 5112:Lattice Theory 5105: 5090: 5075: 5069: 5045: 5044: 5030: 5019: 4999: 4996: 4993: 4992: 4970: 4920: 4862: 4842: 4822: 4813: 4805:available here 4793: 4784: 4775: 4760: 4720: 4711: 4640: 4639: 4637: 4634: 4621: 4618: 4583: 4580: 4578:(or locales). 4560: 4553: 4526: 4503: 4486: 4483: 4447:if and only if 4398: 4375: 4307: 4304: 4298: 4294: βˆ˜  4272: 4228: 4187:on some poset 4165:is called the 4156: 4138: 4134: βˆ˜  4111: 4096: 4087: 4084: 4046: 4036: 4032: βˆ˜  4024: 4023: 4010: 4006:)))) =   3995: 3991: (  3984: 3973: 3972: 3963: 3959: (  3955:)))) =   3948: 3944: (  3937: 3933: (  3922: 3921: 3911: 3900: 3896: (  3889: 3876: 3866: 3862: βˆ˜  3847: 3839: 3838: 3828: 3817: 3813: (  3806: 3780: 3769: 3765: (  3758: 3745: 3698: 3645: 3631: 3627: βˆ˜  3601: 3597: (  3566: 3528:  : 3517: 3500: 3497: 3356: 3353: 3349:affine variety 3328:affine variety 3277: 3276: 3265: 3262: 3259: 3256: 3253: 3243: 3240: 3237: 3234: 3231: 3228: 3225: 3222: 3217: 3213: 3209: 3206: 3203: 3198: 3194: 3190: 3187: 3184: 3181: 3178: 3175: 3172: 3169: 3166: 3163: 3112: 3111: 3100: 3097: 3094: 3091: 3088: 3078: 3075: 3072: 3069: 3066: 3063: 3060: 3055: 3051: 3047: 3044: 3041: 3038: 3035: 3032: 3029: 3026: 2971:natural number 2955: 2952: 2806: 2803: 2788: 2754: 2738:path-connected 2733: 2730: 2609: 2606: 2604: 2601: 2489: 2486: 2458:closed subsets 2379:that contains 2342:underlying set 2333: 2330: 2090: 2087: 2063: 2062: 2051: 2048: 2045: 2042: 2039: 2036: 2033: 2030: 2027: 2024: 2021: 2016: 2012: 2008: 2005: 1980: 1975: 1970: 1927: 1906: 1905: 1894: 1891: 1888: 1885: 1882: 1879: 1876: 1873: 1866: 1863: 1856: 1853: 1850: 1847: 1844: 1841: 1838: 1835: 1832: 1829: 1826: 1823: 1820: 1817: 1814: 1811: 1808: 1805: 1802: 1797: 1758: 1755: 1718: 1715: 1548: 1545: 1544: 1543: 1532: 1529: 1526: 1523: 1520: 1517: 1511: 1505: 1502: 1499: 1469: 1466: 1463: 1460: 1457: 1454: 1451: 1448: 1445: 1442: 1439: 1436: 1416: 1405: 1404: 1393: 1390: 1387: 1384: 1381: 1378: 1372: 1366: 1363: 1360: 1337: 1334: 1331: 1328: 1325: 1322: 1316: 1310: 1307: 1304: 1301: 1298: 1295: 1275: 1272: 1269: 1266: 1263: 1260: 1257: 1254: 1251: 1230: 1226: 1222: 1218: 1215: 1195: 1191: 1187: 1184: 1181: 1178: 1175: 1172: 1169: 1148: 1144: 1140: 1136: 1133: 1122:floor function 1101: 1097: 1072: 1068: 1055: 1054:Floor; ceiling 1052: 1050: 1047: 1034: 1031: 1028: 1025: 1022: 1019: 1016: 996: 993: 990: 987: 984: 981: 961: 958: 955: 952: 949: 929: 926: 923: 920: 917: 889: 886: 883: 880: 877: 874: 854: 851: 848: 845: 842: 826: 823: 821: 818: 712: 711: 679: 631: 630: 545: 542: 449:, and we have 371: 370: 319: 254:(respectively 234:is called the 222:is called the 216: 215: 198:if and only if 102: 99: 97: 94: 15: 9: 6: 4: 3: 2: 5188: 5177: 5174: 5172: 5169: 5167: 5164: 5162: 5161:Galois theory 5159: 5158: 5156: 5146: 5142: 5138: 5134: 5130: 5126: 5125: 5120: 5116: 5113: 5109: 5106: 5103: 5099: 5095: 5091: 5088: 5087:1-85233-905-5 5084: 5080: 5076: 5072: 5070:0-387-98403-8 5066: 5062: 5061: 5056: 5052: 5051: 5050: 5049: 5042: 5039: 5035: 5031: 5028: 5024: 5023:Dana S. Scott 5020: 5017: 5016: 5011: 5007: 5006: 5005: 5004: 4988: 4981: 4974: 4965: 4961: 4957: 4953: 4952: 4942: 4940: 4931: 4924: 4909: 4905: 4901: 4897: 4893: 4889: 4885: 4881: 4877: 4873: 4866: 4860: 4856: 4852: 4846: 4840: 4836: 4832: 4826: 4817: 4810: 4806: 4802: 4797: 4788: 4779: 4771: 4767: 4763: 4761:3-540-21181-0 4757: 4753: 4749: 4744: 4739: 4735: 4731: 4724: 4715: 4707: 4703: 4699: 4695: 4680: 4676: 4672: 4668: 4655: 4651: 4645: 4641: 4633: 4631: 4627: 4617: 4615: 4611: 4610:right adjoint 4607: 4602: 4598: 4593: 4589: 4579: 4577: 4573: 4569: 4559: 4552: 4548: 4544: 4525: 4521: 4502: 4498: 4492: 4482: 4470: 4466: 4462: 4458: 4454: 4448: 4442: 4435: 4433: 4428: 4424: 4420: 4404: 4397: 4381: 4374: 4370: 4355: 4351: 4335: 4333: 4329: 4325: 4321: 4317: 4313: 4303: 4297: 4293: 4286: 4282: 4278: 4271: 4256: 4244: 4240: 4235: 4227: 4219: 4215: 4210: 4196: 4182: 4178: 4174: 4168: 4162: 4155: 4149: 4145: 4137: 4133: 4123: 4120:is in fact a 4117: 4110: 4102: 4095: 4083: 4081: 4075: 4067: 4060: 4058: 4052: 4045: 4035: 4031: 4020: 4016: 4009: 4005: 4001: 3994: 3990: 3983: 3978: 3977: 3976: 3969: 3962: 3958: 3954: 3947: 3943: 3936: 3932: 3927: 3926: 3925: 3917: 3910: 3907:))) ≀   3906: 3899: 3895: 3888: 3883: 3882: 3881: 3875: 3865: 3861: 3853: 3846: 3834: 3827: 3824:))) β‰₯   3823: 3816: 3812: 3805: 3800: 3799: 3798: 3786: 3779: 3776:))) =   3775: 3768: 3764: 3757: 3750: 3744: 3736: 3728: 3724: 3720: 3716: 3708: 3704: 3697: 3693: 3687: 3683: 3677: 3673: 3669: 3665:Now consider 3663: 3661: 3657: 3651: 3644: 3638: 3630: 3626: 3611: 3607: 3600: 3596: 3590: 3576: 3572: 3565: 3561: 3554: 3550: 3546: 3542: 3535: 3531: 3527: 3516: 3512: 3508: 3496: 3494: 3489: 3487: 3482: 3477: 3457: 3453: 3449: 3445: 3441: 3437: 3433: 3418: 3414: 3410: 3406: 3402: 3398: 3394: 3370: 3352: 3350: 3346: 3341: 3337: 3333: 3329: 3322: 3317: 3311: 3307: 3299: 3294: 3288: 3286: 3263: 3257: 3254: 3251: 3241: 3238: 3232: 3226: 3223: 3215: 3211: 3207: 3204: 3201: 3196: 3192: 3185: 3182: 3179: 3173: 3167: 3161: 3154: 3153: 3152: 3146: 3140: 3136: 3130: 3117: 3098: 3092: 3089: 3086: 3076: 3073: 3067: 3061: 3058: 3053: 3049: 3045: 3042: 3036: 3030: 3024: 3017: 3016: 3015: 3013: 3004: 2994: 2990: 2979: 2972: 2967: 2965: 2961: 2951: 2947: 2936: 2932: 2928: 2924: 2920: 2916: 2912: 2908: 2901: 2882: 2878: 2872: 2868: 2856:and a subset 2852: 2847: 2827: 2823: 2819: 2812: 2802: 2794: 2787: 2778: 2766: 2760: 2753: 2749: 2742: 2739: 2729: 2725: 2721: 2714: 2710: 2706: 2691: 2679: 2675: 2657: 2651: 2647: 2634:that contain 2625: 2620: 2616: 2608:Galois theory 2600: 2584: 2576: 2562: 2552: 2545: 2541: 2533: 2527: 2520: 2516: 2507: 2499: 2495: 2485: 2459: 2444: 2438: 2434: 2429: 2415: 2411: 2395:generated by 2394: 2390: 2386: 2374: 2368: 2364: 2351: 2347: 2343: 2329: 2326: 2321: 2310: 2306: 2297: 2293: 2289: 2284: 2260: 2256: 2252: 2248: 2244: 2240: 2236: 2205: 2201: 2197: 2193: 2189: 2185: 2181: 2177: 2173: 2169: 2168:inverse image 2155: 2151: 2147: 2143: 2139: 2135: 2131: 2127: 2123: 2111: 2106: 2102: 2098: 2086: 2084: 2072: 2068: 2046: 2043: 2040: 2037: 2034: 2031: 2028: 2025: 2019: 2014: 2010: 2003: 1996: 1995: 1994: 1957: 1951: 1943: 1911: 1892: 1883: 1880: 1877: 1874: 1871: 1854: 1851: 1848: 1845: 1842: 1839: 1836: 1833: 1827: 1824: 1821: 1818: 1815: 1812: 1809: 1806: 1800: 1786: 1785: 1784: 1770: 1767: 1754: 1752: 1746: 1740: 1736: 1732: 1728: 1724: 1714: 1704: 1698: 1694: 1690: 1686: 1682: 1678: 1671: 1667: 1663: 1659: 1654: 1650: 1646: 1636: 1632: 1628: 1624: 1620: 1614: 1610: 1606: 1602: 1582: 1578: 1575:, ordered by 1570: 1558: 1530: 1527: 1524: 1518: 1503: 1500: 1497: 1490: 1489: 1488: 1486: 1481: 1467: 1464: 1461: 1455: 1449: 1443: 1440: 1437: 1414: 1391: 1385: 1379: 1376: 1364: 1361: 1358: 1351: 1350: 1349: 1332: 1326: 1323: 1320: 1308: 1305: 1299: 1293: 1273: 1267: 1261: 1255: 1249: 1216: 1213: 1193: 1185: 1182: 1179: 1173: 1167: 1134: 1131: 1123: 1119: 1115: 1099: 1086: 1070: 1046: 1032: 1026: 1020: 1017: 1014: 994: 991: 985: 979: 956: 953: 950: 924: 921: 918: 907: 906:partial order 903: 887: 884: 878: 875: 872: 852: 846: 843: 840: 832: 817: 810: 806: 789: 777: 773: 769: 754: 750: 746: 740: 736: 732: 726: 722: 718: 707: 703: 699: 688: 684: 680: 675: 671: 667: 656: 652: 648: 647: 646: 644: 626: 622: 618: 611: 607: 603: 599: 598: 597: 586: 582: 578: 572: 568: 564: 559: 555: 554:domain theory 551: 541: 531: 516: 500: 495: 484: 480: 476: 461: 457: 453: 448: 443: 439: 435: 430: 425: 421: 417: 413: 400: 397: 393: 388: 384: 367: 360: 350: 341: 328: 324: 320: 312: 302: 298: 289: 276: 272: 268: 267: 266: 264: 259: 257: 256:right adjoint 253: 249: 245: 241: 237: 236:upper adjoint 225: 224:lower adjoint 211: 207: 203: 199: 195: 191: 187: 183: 182: 181: 162: 158: 154: 148: 144: 140: 135: 132: 128: 124: 118: 110: 93: 91: 87: 84: 80: 76: 71: 69: 65: 61: 57: 52: 50: 46: 42: 38: 34: 30: 26: 22: 5166:Order theory 5128: 5122: 5119:Ore, Øystein 5111: 5096:, Elsevier, 5093: 5078: 5058: 5047: 5046: 5033: 5026: 5013: 5002: 5001: 4986: 4973: 4950: 4936: 4923: 4912:. Retrieved 4879: 4875: 4865: 4850: 4845: 4830: 4825: 4816: 4796: 4787: 4778: 4729: 4723: 4718:Gierz, p. 23 4714: 4705: 4701: 4697: 4693: 4683:and for all 4678: 4674: 4670: 4666: 4653: 4644: 4623: 4614:left adjoint 4613: 4609: 4600: 4596: 4591: 4587: 4585: 4557: 4550: 4546: 4542: 4523: 4519: 4500: 4496: 4488: 4468: 4464: 4460: 4456: 4452: 4440: 4436: 4426: 4422: 4418: 4402: 4395: 4379: 4372: 4368: 4353: 4349: 4336: 4309: 4295: 4291: 4284: 4280: 4276: 4269: 4257: 4242: 4238: 4225: 4217: 4213: 4194: 4179: 4172: 4166: 4160: 4153: 4143: 4135: 4131: 4115: 4108: 4100: 4093: 4089: 4073: 4065: 4061: 4050: 4043: 4033: 4029: 4025: 4018: 4014: 4007: 4003: 3999: 3992: 3988: 3981: 3974: 3967: 3960: 3956: 3952: 3945: 3941: 3934: 3930: 3923: 3915: 3908: 3904: 3897: 3893: 3886: 3873: 3863: 3859: 3851: 3844: 3840: 3832: 3825: 3821: 3814: 3810: 3803: 3784: 3777: 3773: 3766: 3762: 3755: 3751: 3742: 3734: 3726: 3722: 3718: 3714: 3706: 3702: 3695: 3691: 3685: 3681: 3675: 3671: 3667: 3664: 3659: 3656:inflationary 3655: 3649: 3642: 3637:deflationary 3636: 3628: 3624: 3609: 3605: 3598: 3594: 3574: 3570: 3563: 3559: 3552: 3548: 3544: 3540: 3533: 3529: 3525: 3514: 3510: 3506: 3502: 3490: 3480: 3478: 3455: 3451: 3447: 3443: 3439: 3435: 3431: 3416: 3412: 3408: 3404: 3400: 3396: 3392: 3390:, we define 3358: 3342: 3335: 3318: 3292: 3289: 3284: 3278: 3138: 3134: 3128: 3113: 3014:of zeros as 3002: 2992: 2968: 2957: 2945: 2934: 2930: 2926: 2922: 2918: 2914: 2910: 2906: 2899: 2880: 2870: 2866: 2851:vector space 2848: 2825: 2821: 2808: 2792: 2785: 2758: 2751: 2735: 2723: 2719: 2712: 2708: 2704: 2689: 2677: 2673: 2649: 2645: 2618: 2614: 2611: 2582: 2574: 2550: 2543: 2539: 2525: 2518: 2514: 2497: 2491: 2436: 2432: 2413: 2409: 2366: 2362: 2350:vector space 2340:that has an 2335: 2324: 2319: 2316:is given by 2308: 2304: 2288:quotient map 2285: 2258: 2254: 2250: 2246: 2242: 2238: 2234: 2203: 2199: 2195: 2191: 2187: 2183: 2179: 2175: 2171: 2153: 2149: 2145: 2141: 2137: 2133: 2129: 2125: 2104: 2100: 2096: 2092: 2064: 1958: 1909: 1907: 1769:transitively 1760: 1744: 1738: 1734: 1730: 1727:diagonal map 1720: 1696: 1692: 1688: 1684: 1683:) = (  1680: 1676: 1669: 1665: 1661: 1657: 1634: 1630: 1626: 1622: 1618: 1612: 1608: 1604: 1600: 1567:both be the 1550: 1482: 1406: 1114:real numbers 1057: 828: 808: 790: 775: 771: 767: 752: 748: 744: 738: 734: 730: 724: 720: 716: 713: 705: 701: 697: 686: 682: 673: 669: 665: 654: 650: 642: 632: 624: 620: 616: 609: 605: 601: 596:, such that 584: 580: 576: 570: 566: 562: 557: 547: 521:, and hence 498: 496: 482: 478: 474: 459: 455: 451: 441: 437: 433: 423: 419: 415: 412:compositions 401: 395: 391: 372: 365: 358: 348: 339: 326: 322: 310: 300: 296: 287: 274: 270: 262: 260: 255: 252:left adjoint 251: 239: 235: 223: 217: 209: 205: 201: 193: 189: 185: 160: 156: 152: 146: 142: 138: 126: 116: 108: 104: 85: 78: 72: 67: 63: 53: 28: 25:order theory 18: 4207:(i.e. as a 4169:induced by 3721:) ≀   3547:) ≀   2964:polynomials 2666:fixed. Let 2383:, i.e. the 1912:containing 1908:the set of 1783:. Consider 1625: ) = 1607: ) = 1112:the set of 1083:the set of 536:  of 96:Definitions 21:mathematics 5155:Categories 4998:References 4937:Proc. 4th 4914:2023-07-19 4882:: 84–114. 4743:cs/0208008 4650:properties 4491:categories 4415:such that 4366:such that 4262:(elements 4209:surjective 4181:Conversely 4128:. Dually, 4057:idempotent 3789:, for all 3679:such that 3613:, for all 3579:, for all 3509:= (  3499:Properties 3345:subschemes 3151:, that is 2877:dual space 2662:that hold 2140:= {  2067:one-to-one 1950:stabilizer 1559:, and let 825:Bijections 805:order dual 643:polarities 447:idempotent 180:, we have 4964:1435-2702 4904:219514253 4896:0304-3975 4770:0302-9743 4572:morphisms 4545:∘   4471: }, 4459:|   4371:≀   4234:inclusion 3694:≀   3660:extensive 3562:≀   3458: }. 3429:, define 3419: }. 3255:∈ 3205:… 3183:∈ 3132:, define 3090:∈ 3046:∈ 2937: }. 2809:Given an 2686:, define 2373:subobject 2249:|   2232:, define 2194:|   2071:corollary 2044:∈ 2029:∈ 2007:↦ 1974:→ 1942:subgroups 1887:∅ 1878:∩ 1837:∈ 1831:∀ 1822:∈ 1810:⊆ 1577:inclusion 1569:power set 1525:≤ 1522:⌉ 1516:⌈ 1510:⇔ 1501:≤ 1459:⌋ 1453:⌊ 1447:⌋ 1435:⌊ 1389:⌋ 1383:⌊ 1380:≤ 1371:⇔ 1362:≤ 1324:≤ 1315:⇔ 1306:≤ 1271:⌋ 1265:⌊ 1225:→ 1186:∈ 1143:→ 1118:embedding 908:, making 882:→ 850:→ 831:bijection 383:bijective 134:functions 83:bijective 45:subfields 41:subgroups 4908:Archived 4696: ( 4677: ( 4673:(  4654:antitone 4531:between 4495:(  4451:{  4312:preserve 4275:(  4159:∘  4114:∘  4099:∘  4049:∘  4013:(  3998:(  3987:(  3940:(  3892:(  3850:∘  3841:because 3809:(  3761:(  3701:(  3648:∘  3639:, while 3569:(  3522:, where 3359:Suppose 3141: ) 2983:and let 2873: ) 2849:Given a 2828: ) 2585: ) 2577: ) 2553: ) 2528: ) 2496:is that 2439: ) 2426:to be a 2416: ) 2393:subspace 2385:subgroup 2369: ) 2198: ( 2144: ( 2110:function 2099: : 1717:Lattices 1679:(  1598:, where 1555:be some 1085:integers 820:Examples 803:and the 780:for all 757:for all 733: : 719: : 579: : 565: : 558:antitone 515:identity 486:for all 464:for all 436: : 418: : 263:uniquely 155: : 141: : 131:monotone 5145:1990305 4568:duality 4463: ( 4439:  4421: ( 4417:  4394:  4352: ( 4348:  4316:suprema 4290:  4279: ( 4268:  4224:  4193:  4171:  4167:nucleus 4152:  4130:  4107:  4092:  4076:  4072:  4068:  4064:  4042:  4028:  4017: ( 4002: ( 3980:  3929:  3885:  3872:  3858:  3843:  3802:  3754:  3741:  3733:  3725: ( 3717: ( 3713:  3705: ( 3641:  3623:  3593:  3573: ( 3551: ( 3543: ( 3539:  3524:  3505:  3310:radical 3143:as the 3012:variety 2948:  2929:) = 0 βˆ€ 2902:  2883:  2464:.) Now 2443:closure 2389:subring 2253: { 2136:  2095:  1703:logical 1645:infimum 550:lattice 513:is the 387:inverse 121:be two 60:classes 5143:  5100:  5085:  5067:  4962:  4941:(POPL) 4902:  4894:  4857:  4837:  4768:  4758:  4576:frames 4443:  4324:infima 4320:domain 4197:  4175:  4163:  4118:  4103:  4053:  4026:i.e., 3854:  3737:  3652:  2976:and a 2969:Fix a 2722:↦ Fix( 2707:↦ Gal( 2626:. Let 2547:, let 2532:axioms 2522:, let 2430:, let 2407:, let 2360:, let 2292:groups 2182:  1910:blocks 1869:  1858:  1747:β†’ {1}. 1616:, and 1581:subset 1513:  1507:  1374:  1368:  1318:  1312:  1206:while 431:, and 5141:JSTOR 5038:PS.GZ 4983:(PDF) 4933:(PDF) 4900:S2CID 4738:arXiv 4704:)) ≀ 4636:Notes 4283:)) = 4266:with 4247:into 4078:is a 3608:)) ≀ 3460:Then 3374:over 3279:Then 3145:ideal 3122:. If 3116:zeros 2978:field 2622:is a 2263:Then 2241:) = { 2208:Then 2122:image 2108:is a 1701:. In 1691:) = ( 1664:) = ( 695:with 678:, and 663:with 505:into 346:with 318:, and 294:with 5098:ISBN 5083:ISBN 5065:ISBN 4960:ISSN 4892:ISSN 4855:ISBN 4835:ISBN 4766:ISSN 4756:ISBN 4535:and 4516:and 4512:and 4473:for 4467:) ≀ 4425:) ≀ 4314:all 4055:are 4040:and 3975:and 3658:(or 3491:The 3472:and 3464:and 3378:and 3363:and 3332:Spec 3283:and 2717:and 2688:Fix( 2672:Gal( 2644:Gal( 2573:Mod( 2559:(in 2524:Mod( 2468:and 2456:the 2441:the 2346:ring 2267:and 2257:} βŠ† 2212:and 2202:) ∈ 2148:) | 1761:Let 1674:and 1594:and 1563:and 1087:and 940:and 865:and 829:The 795:and 765:and 728:and 637:and 592:and 574:and 552:and 530:onto 481:) ≀ 472:and 364:) ≀ 230:and 192:) ≀ 172:and 150:and 125:. A 119:, ≀) 113:and 111:, ≀) 105:Let 66:and 43:and 27:, a 5133:doi 4956:GMD 4884:doi 4880:837 4748:doi 4687:in 4660:in 4628:of 4590:to 4477:in 4411:in 4388:in 4362:of 4342:in 4236:of 4124:on 3793:in 3662:). 3654:is 3635:is 3617:in 3583:in 3481:all 3448:xRn 3425:of 3409:mRy 3386:of 3304:is 2958:In 2897:of 2885:of 2860:of 2834:of 2783:of 2775:is 2767:of 2658:of 2593:Mod 2581:Th( 2549:Th( 2460:of 2445:of 2403:of 2391:or 2375:of 2356:of 2228:of 2186:= { 2162:of 2116:of 2093:If 1952:of 1944:of 1779:in 1771:on 1766:act 1713:". 1687:∨ Β¬ 1629:βˆͺ ( 1586:of 1571:of 1557:set 812:of 784:in 761:in 517:on 501:of 490:in 468:in 381:is 377:or 246:in 238:of 226:of 176:in 168:in 58:or 19:In 5157:: 5139:, 5129:55 5127:, 5110:: 5041:PS 5025:: 5012:: 4985:. 4935:. 4906:. 4898:. 4890:. 4878:. 4874:. 4764:. 4754:. 4746:. 4691:, 4681:)) 4669:≀ 4664:, 4632:. 4599:≀ 4556:∘ 4522:, 4455:∈ 4392:, 4346:, 4059:. 4021:)) 3970:)) 3709:)) 3684:≀ 3674:∈ 3670:, 3577:)) 3532:β†’ 3454:∈ 3446:| 3442:∈ 3415:∈ 3407:| 3403:∈ 3351:. 3340:. 3316:. 2950:. 2933:∈ 2921:| 2917:∈ 2846:. 2597:Th 2542:∈ 2517:∈ 2387:, 2348:, 2328:. 2325:HN 2323:= 2261:}. 2245:∈ 2206:}. 2190:∈ 2156:} 2152:∈ 2103:β†’ 1993:: 1956:. 1737:Γ— 1733:β†’ 1695:β‡’ 1668:∧ 1611:∩ 1487:: 788:. 772:FG 770:≀ 749:GF 747:≀ 737:β†’ 731:FG 723:β†’ 717:GF 700:≀ 668:≀ 619:≀ 604:≀ 583:β†’ 569:β†’ 540:. 534:GF 511:FG 497:A 494:. 475:FG 456:GF 454:≀ 440:β†’ 434:FG 422:β†’ 416:GF 399:. 394:= 299:≀ 204:≀ 159:β†’ 145:β†’ 136:: 70:. 51:. 5135:: 5104:. 5089:. 5073:. 4966:. 4917:. 4886:: 4772:. 4750:: 4740:: 4709:. 4706:y 4702:y 4700:( 4698:g 4694:f 4689:B 4685:y 4679:x 4675:f 4671:g 4667:x 4662:A 4658:x 4601:y 4597:x 4592:y 4588:x 4563:) 4561:βˆ— 4558:g 4554:βˆ— 4551:f 4547:f 4543:g 4541:( 4537:C 4533:B 4529:) 4527:βˆ— 4524:g 4520:g 4518:( 4514:B 4510:A 4506:) 4504:βˆ— 4501:f 4497:f 4479:B 4475:b 4469:b 4465:x 4461:f 4457:A 4453:x 4441:f 4427:y 4423:x 4419:f 4413:A 4409:x 4405:) 4403:y 4401:( 4399:βˆ— 4396:f 4390:B 4386:y 4382:) 4380:y 4378:( 4376:βˆ— 4373:f 4369:x 4364:B 4360:y 4356:) 4354:x 4350:f 4344:A 4340:x 4299:βˆ— 4296:f 4292:f 4285:x 4281:x 4277:f 4273:βˆ— 4270:f 4264:x 4260:A 4253:A 4249:A 4245:) 4243:A 4241:( 4239:c 4229:βˆ— 4226:f 4220:) 4218:A 4216:( 4214:c 4205:c 4201:c 4195:f 4189:A 4185:c 4173:f 4161:f 4157:βˆ— 4154:f 4139:βˆ— 4136:f 4132:f 4126:A 4116:f 4112:βˆ— 4109:f 4101:f 4097:βˆ— 4094:f 4074:f 4066:f 4051:f 4047:βˆ— 4044:f 4037:βˆ— 4034:f 4030:f 4019:x 4015:f 4011:βˆ— 4008:f 4004:x 4000:f 3996:βˆ— 3993:f 3989:f 3985:βˆ— 3982:f 3968:x 3966:( 3964:βˆ— 3961:f 3957:f 3953:x 3951:( 3949:βˆ— 3946:f 3942:f 3938:βˆ— 3935:f 3931:f 3920:. 3918:) 3916:x 3914:( 3912:βˆ— 3909:f 3905:x 3903:( 3901:βˆ— 3898:f 3894:f 3890:βˆ— 3887:f 3877:βˆ— 3874:f 3867:βˆ— 3864:f 3860:f 3852:f 3848:βˆ— 3845:f 3837:. 3835:) 3833:x 3831:( 3829:βˆ— 3826:f 3822:x 3820:( 3818:βˆ— 3815:f 3811:f 3807:βˆ— 3804:f 3795:B 3791:x 3787:) 3785:x 3783:( 3781:βˆ— 3778:f 3774:x 3772:( 3770:βˆ— 3767:f 3763:f 3759:βˆ— 3756:f 3746:βˆ— 3743:f 3735:f 3729:) 3727:y 3723:f 3719:x 3715:f 3707:y 3703:f 3699:βˆ— 3696:f 3692:x 3686:y 3682:x 3676:A 3672:y 3668:x 3650:f 3646:βˆ— 3643:f 3632:βˆ— 3629:f 3625:f 3619:B 3615:y 3610:y 3606:y 3604:( 3602:βˆ— 3599:f 3595:f 3585:A 3581:x 3575:x 3571:f 3567:βˆ— 3564:f 3560:x 3555:) 3553:x 3549:f 3545:x 3541:f 3534:B 3530:A 3526:f 3520:) 3518:βˆ— 3515:f 3511:f 3507:f 3474:Y 3470:X 3466:G 3462:F 3456:N 3452:n 3450:βˆ€ 3444:X 3440:x 3436:N 3434:( 3432:G 3427:Y 3423:N 3417:M 3413:m 3411:βˆ€ 3405:Y 3401:y 3397:M 3395:( 3393:F 3388:X 3384:M 3380:Y 3376:X 3372:R 3365:Y 3361:X 3338:) 3336:R 3334:( 3324:R 3314:S 3302:K 3293:K 3285:I 3281:V 3264:. 3261:} 3258:U 3252:x 3242:0 3239:= 3236:) 3233:x 3230:( 3227:f 3224:: 3221:] 3216:n 3212:X 3208:, 3202:, 3197:1 3193:X 3189:[ 3186:K 3180:f 3177:{ 3174:= 3171:) 3168:U 3165:( 3162:I 3149:U 3139:U 3137:( 3135:I 3129:K 3124:U 3120:S 3099:, 3096:} 3093:S 3087:f 3077:0 3074:= 3071:) 3068:x 3065:( 3062:f 3059:: 3054:n 3050:K 3043:x 3040:{ 3037:= 3034:) 3031:S 3028:( 3025:V 3008:S 3003:K 2998:B 2993:K 2985:A 2981:K 2974:n 2946:V 2941:V 2935:Y 2931:Ο† 2927:x 2925:( 2923:Ο† 2919:V 2915:x 2911:Y 2909:( 2907:G 2900:V 2895:Y 2891:X 2887:V 2881:V 2871:X 2869:( 2867:F 2862:V 2858:X 2854:V 2844:F 2840:V 2836:V 2832:X 2826:X 2824:( 2822:F 2814:V 2799:G 2795:) 2793:X 2791:( 2789:1 2786:Ο€ 2781:G 2773:X 2769:X 2761:) 2759:X 2757:( 2755:1 2752:Ο€ 2744:X 2726:) 2724:G 2720:G 2715:) 2713:E 2711:/ 2709:L 2705:E 2700:G 2696:L 2692:) 2690:G 2684:G 2680:) 2678:K 2676:/ 2674:L 2668:B 2664:E 2660:L 2652:) 2650:E 2648:/ 2646:L 2640:E 2636:K 2632:L 2628:A 2619:K 2617:/ 2615:L 2589:T 2583:S 2575:T 2569:S 2565:S 2557:S 2551:S 2544:B 2540:S 2535:T 2526:T 2519:A 2515:T 2510:B 2502:A 2482:F 2478:X 2474:X 2470:G 2466:F 2462:X 2454:" 2451:X 2447:S 2437:S 2435:( 2433:F 2424:X 2420:U 2414:U 2412:( 2410:G 2405:X 2401:U 2397:S 2381:S 2377:X 2367:S 2365:( 2363:F 2358:X 2354:S 2338:X 2320:H 2314:G 2309:N 2307:/ 2305:G 2300:G 2281:G 2277:X 2273:Y 2269:H 2265:G 2259:M 2255:y 2251:f 2247:Y 2243:y 2239:M 2237:( 2235:H 2230:X 2226:M 2222:Y 2218:X 2214:G 2210:F 2204:N 2200:x 2196:f 2192:X 2188:x 2184:N 2180:f 2176:N 2174:( 2172:G 2164:Y 2160:N 2154:M 2150:m 2146:m 2142:f 2138:M 2134:f 2130:M 2128:( 2126:F 2118:X 2114:M 2105:Y 2101:X 2097:f 2079:G 2075:X 2050:} 2047:B 2041:x 2038:g 2035:: 2032:G 2026:g 2023:{ 2020:= 2015:B 2011:H 2004:B 1979:G 1969:B 1954:x 1946:G 1926:G 1914:x 1893:, 1890:} 1884:= 1881:B 1875:B 1872:g 1865:r 1862:o 1855:B 1852:= 1849:B 1846:g 1843:, 1840:G 1834:g 1828:; 1825:B 1819:x 1816:: 1813:X 1807:B 1804:{ 1801:= 1796:B 1781:X 1777:x 1773:X 1763:G 1745:X 1739:X 1735:X 1731:X 1711:a 1707:a 1699:) 1697:y 1693:a 1689:a 1685:y 1681:y 1677:G 1672:) 1670:x 1666:a 1662:x 1660:( 1658:F 1641:F 1637:) 1635:L 1631:U 1627:N 1623:N 1621:( 1619:G 1613:M 1609:L 1605:M 1603:( 1601:F 1596:G 1592:F 1588:U 1584:L 1573:U 1565:B 1561:A 1553:U 1531:. 1528:n 1519:x 1504:n 1498:x 1468:, 1465:n 1462:+ 1456:x 1450:= 1444:n 1441:+ 1438:x 1415:n 1392:. 1386:x 1377:n 1365:x 1359:n 1336:) 1333:x 1330:( 1327:G 1321:n 1309:x 1303:) 1300:n 1297:( 1294:F 1274:. 1268:x 1262:= 1259:) 1256:x 1253:( 1250:G 1229:Z 1221:R 1217:: 1214:G 1194:, 1190:R 1183:n 1180:= 1177:) 1174:n 1171:( 1168:F 1147:R 1139:Z 1135:: 1132:F 1100:, 1096:R 1071:, 1067:Z 1033:, 1030:) 1027:y 1024:( 1021:g 1018:= 1015:x 995:y 992:= 989:) 986:x 983:( 980:f 960:) 957:= 954:, 951:Y 948:( 928:) 925:= 922:, 919:X 916:( 888:, 885:X 879:Y 876:: 873:g 853:Y 847:X 844:: 841:f 814:B 809:B 801:A 797:B 793:A 786:B 782:b 778:) 776:b 774:( 768:b 763:A 759:a 755:) 753:a 751:( 745:a 739:B 735:B 725:A 721:A 710:. 708:) 706:a 704:( 702:F 698:b 693:a 689:) 687:b 685:( 683:G 676:) 674:b 672:( 670:G 666:a 661:b 657:) 655:a 653:( 651:F 639:G 635:F 629:. 627:) 625:b 623:( 621:G 617:a 612:) 610:a 608:( 606:F 602:b 594:B 590:A 585:A 581:B 577:G 571:B 567:A 563:F 538:A 527:B 523:G 519:B 507:A 503:B 492:B 488:b 483:b 479:b 477:( 470:A 466:a 462:) 460:a 458:( 452:a 442:B 438:B 424:A 420:A 408:G 404:F 396:G 392:F 379:G 375:F 369:. 366:b 359:a 355:~ 351:( 349:F 340:a 336:~ 329:) 327:b 325:( 323:G 316:) 311:b 307:~ 303:( 301:G 297:a 288:b 284:~ 277:) 275:a 273:( 271:F 240:F 232:G 228:G 220:F 214:. 212:) 210:b 208:( 206:G 202:a 194:b 190:a 188:( 186:F 178:B 174:b 170:A 166:a 161:A 157:B 153:G 147:B 143:A 139:F 117:B 115:( 109:A 107:(

Index

mathematics
order theory
partially ordered sets
fundamental theorem of Galois theory
subgroups
subfields
Γ‰variste Galois
preordered sets
classes
order isomorphism
bijective
order isomorphism
partially ordered sets
monotone
functions
if and only if
adjoint functors
category theory
bijective
inverse
compositions
closure operator
idempotent
identity
onto
lattice
domain theory
order dual
bijection
equality relation

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