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Inverse semigroup

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Thus, any inverse semigroup can be embedded in a symmetric inverse semigroup, and with image closed under the inverse operation on partial bijections. Conversely, any subsemigroup of the symmetric inverse semigroup closed under the inverse operation is an inverse semigroup. Hence a semigroup
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The above composition of partial transformations of a set gives rise to a symmetric inverse semigroup. There is another way of composing partial transformations, which is more restrictive than that used above: two partial transformations
1973: 2285: 4400:, which states that an inductive groupoid can always be constructed from an inverse semigroup, and conversely. More precisely, an inverse semigroup is precisely a groupoid in the category of posets that is an 278: 719: 2642: 1379: 1312: 3934: 3802: 4048: 3885: 3541: 3351: 2034: 1589: 1213: 1152: 2386: 3749: 2436: 4388:; otherwise, the composition αβ is undefined. Under this alternative composition, the collection of all partial one-one transformations of a set forms not an inverse semigroup but an 3553: 4356:
who showed that elements of the free inverse semigroup can be naturally regarded as trees, known as Munn trees. Multiplication in the free inverse semigroup has a correspondent on
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Every inverse semigroup S has a E-unitary cover; that is there exists an idempotent separating surjective homomorphism from some E-unitary semigroup T onto S.
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to take account of this. With the addition of this empty transformation, the composition of partial transformations of a set becomes an everywhere-defined
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commute; this has led to two distinct classes of generalisations of an inverse semigroup: semigroups in which (1) holds, but (2) does not, and vice versa.
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in which every element has a unique inverse. Inverse semigroups appear in a range of contexts; for example, they can be employed in the study of
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Since his father was German, Wagner preferred the German transliteration of his name (with a "W", rather than a "V") from Cyrillic – see
210: 836:{\displaystyle a\,{\mathcal {L}}\,b\Longleftrightarrow a^{-1}a=b^{-1}b,\quad a\,{\mathcal {R}}\,b\Longleftrightarrow aa^{-1}=bb^{-1}} 2583: 299:. It was Wagner, however, who was the first to observe that the composition of partial transformations is a special case of the 1323: 1261: 5575: 5492: 5473: 5032: 4147: 5439: 5721: 5810: 4741: 4688: 3890: 3758: 1753:, however, there is no need to do so, since this property follows from the above definition, via the following theorem: 4007: 3844: 3500: 3310: 2008: 1550: 1174: 1113: 355: 122: 4352:
for free inverse semigroups is much more intricate than that of free groups. A celebrated result in this area due to
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of an inverse semigroup is an inverse semigroup; the inverse of an element is always mapped to the inverse of the
5815: 4589: 4360:, which essentially consists of overlapping common portions of the trees. (see Lawson 1998 for further details) 3677: 3661:{\displaystyle P(G,{\mathcal {X}},{\mathcal {Y}})=\{(A,g)\in {\mathcal {Y}}\times G:g^{-1}A\in {\mathcal {Y}}\}} 2397: 4139: 1685:) of inverse semigroups is defined in exactly the same way as for any other semigroup: for inverse semigroups 300: 97:(The convention followed in this article will be that of writing a function on the right of its argument, e.g. 4349: 4618: 1793: 1694: 157: 5026: 4389: 2683: 1880:
is isomorphic to a subsemigroup of the symmetric inverse semigroup closed under inverses if and only if
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Gonçalves, D; Sobottka, M; Starling, C (2017). "Inverse semigroup shifts over countable alphabets".
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Multiplication table example. It is associative and every element has its own inverse according to
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Homological Algebra: The Interplay of Homology with Distributive Lattices and Orthodox Semigroups
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One class of inverse semigroups that has been studied extensively over the years is the class of
1638: 884: 113:), and composing functions from left to right—a convention often observed in semigroup theory.) 91: 4353: 2065: 4772: 4357: 5571: 5488: 5469: 5345: 5315: 5307: 5286: 5165: 5159: 4778: 4751: 4721: 4681: 4541: 4520: 4492: 4444: 4425: 4396:. This close connection between inverse semigroups and inductive groupoids is embodied in the 504: 364: 303:. He recognised also that the domain of composition of two partial transformations may be the 142: 138: 87: 5280: 2810: 1981: 5786: 5694: 5666: 5636: 5615: 5594: 5544: 5511: 5426: 5395: 5372: 5014: 2039: 918: 863: 315: 146: 2552: 2524: 5685: 5657: 4736: 4393: 1630: 380: 368: 1895:
are defined on inverse semigroups in exactly the same way as for any other semigroup: a
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of the class of locally inverse semigroups and the class of orthodox semigroups.
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Wagner, V. V. (1953). "The theory of generalised heaps and generalised groups".
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Exel, R. (1998). "Partial actions of groups and actions of inverse semigroups".
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Gołab, St. (1939). "Über den Begriff der "Pseudogruppe von Transformationen"".
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it is possible to obtain an analogous result under additional hypotheses on
4449: 4151: 1862: 866: 384: 304: 44: 1968:{\displaystyle a\,\rho \,b,\quad c\,\rho \,d\Longrightarrow ac\,\rho \,bd.} 480:
There are a number of equivalent characterisations of an inverse semigroup
5698: 5344:. Mathematical Surveys of the American Mathematical Society. Vol. 7. 5606:
Preston, G. B. (1954b). "Inverse semi-groups with minimal right ideals".
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McAlister, D. B. (1974a). "Groups, semilattices and inverse semigroups".
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relation ≤ (sometimes denoted by ω), which is defined by the following:
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are composed if, and only if, the image of α is equal to the domain of
2280:{\displaystyle a\in S,e\in E(S),a\,\rho \,e\Longrightarrow a\in E(S).} 367:). This is the "archetypal" inverse semigroup, in the same way that a 5795: 4595:
Amongst the non-regular generalisations of an inverse semigroup are:
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in 1954. Both authors arrived at inverse semigroups via the study of
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One of the earliest results proved about inverse semigroups was the
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will denote the semilattice of idempotents of an inverse semigroup
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Preston, G. B. (1954c). "Representations of inverse semi-groups".
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if every element has at least one inverse; equivalently, for each
3979:-unitary monoid. McAlister's covering theorem has been refined by 3967:
maximal element above it in the natural partial order, i.e. every
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Examples of regular generalisations of an inverse semigroup are:
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The natural partial order on an inverse semigroup interacts with
273:{\displaystyle \operatorname {dom} \alpha \beta =\alpha ^{-1}\,} 2658:-unitary inverse semigroups is the following construction. Let 2116:
is a group. In the set of all group congruences on a semigroup
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is compatible with both multiplication and inversion, that is,
385:§ Homomorphisms and representations of inverse semigroups 440:
are not necessarily equal to the identity, but they are both
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form a semilattice under the product operation, products on
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For a brief introduction to inverse semigroups, see either
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simply reduces to equality, since the identity is the only
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is an inverse semigroup under this multiplication, with
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that is compatible with semigroup multiplication, i.e.,
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Homomorphisms and representations of inverse semigroups
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Inverse categories have found various applications in
3547:. A McAlister triple is used to define the following: 4166: 4108: 4084: 4060: 4010: 3893: 3847: 3761: 3680: 3556: 3503: 3475: 3451: 3403: 3367: 3313: 3267: 3204: 3159: 3131: 3072: 3028: 2988: 2950: 2922: 2890: 2862: 2836: 2813: 2783: 2747: 2720: 2692: 2664: 2586: 2555: 2527: 2400: 2350: 2208: 2068: 2042: 2011: 1984: 1915: 1809: 1553: 1505: 1462: 1326: 1264: 1177: 1116: 722: 683: 644: 608: 584: 556: 532: 324: 213: 5485:
Inverse Semigroups: The Theory of Partial Symmetries
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can be composed (from left to right) on the largest
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Inverse semigroups were introduced independently by
5653:"Obituary: Viktor Vladimirovich Vagner (1908–1981)" 5161:
Semigroups: An Introduction to the Structure Theory
4617:This notion of inverse also readily generalizes to 709:. There is therefore a simple characterisation of 5772:"On inverse categories and transfer in cohomology" 4408:and whose poset of objects is a meet-semilattice. 4337: 4118: 4094: 4070: 4042: 3929:{\displaystyle P(G,{\mathcal {X}},{\mathcal {Y}})} 3928: 3879: 3797:{\displaystyle P(G,{\mathcal {X}},{\mathcal {Y}})} 3796: 3743: 3660: 3535: 3485: 3461: 3413: 3377: 3353:is also assumed to have the following properties: 3345: 3277: 3214: 3169: 3141: 3082: 3038: 2998: 2960: 2932: 2900: 2872: 2846: 2819: 2793: 2757: 2730: 2702: 2674: 2636: 2561: 2533: 2430: 2380: 2302:-unitary inverse semigroups: an inverse semigroup 2279: 2089: 2054: 2028: 1990: 1967: 1826: 1583: 1517: 1474: 1373: 1306: 1207: 1146: 835: 693: 654: 618: 594: 566: 542: 341: 272: 5779:Proceedings of the Edinburgh Mathematical Society 5758:More comprehensive introductions can be found in 5537:Transactions of the American Mathematical Society 5504:Transactions of the American Mathematical Society 5365:Proceedings of the Edinburgh Mathematical Society 4608:Weakly (left, right, two-sided) ample semigroups. 4605:(Left, right, two-sided) semiadequate semigroups. 4043:{\displaystyle (G,{\mathcal {X}},{\mathcal {Y}})} 3880:{\displaystyle (G,{\mathcal {X}},{\mathcal {Y}})} 3536:{\displaystyle (G,{\mathcal {X}},{\mathcal {Y}})} 3346:{\displaystyle (G,{\mathcal {X}},{\mathcal {Y}})} 2029:{\displaystyle a\,\sigma \,b\Longleftrightarrow } 5533:"Groups, semilattices and inverse semigroups II" 5409:Proceedings of the American Mathematical Society 4004:-inverse semigroups as well. A McAlister triple 1584:{\displaystyle e\leq f\Longleftrightarrow e=ef,} 1208:{\displaystyle a\leq b\Longleftrightarrow a=bf,} 1147:{\displaystyle a\leq b\Longleftrightarrow a=eb,} 349:of all partial one-one transformations of a set 5748: 5585:Preston, G. B. (1954a). "Inverse semi-groups". 5211: 5209: 5045: 4982: 4825:, then a much more comprehensive exposition in 3940:-unitary inverse semigroup. Conversely, every 2381:{\displaystyle es\in E\Longrightarrow s\in E.} 4599:(Left, right, two-sided) adequate semigroups. 2498:of idempotents, and minimum group congruence 1606:) give least upper bounds with respect to ≤. 952:. It has no identity and is not commutative. 204:upon which it "makes sense" to compose them: 8: 5306:Hines, Peter; Braunstein, Samuel L. (2010). 4329: 4167: 3655: 3592: 873:form an inverse semigroup under composition. 5712:Proceedings of the USSR Academy of Sciences 5314:. Cambridge University Press. p. 369. 5629:Journal of the London Mathematical Society 5608:Journal of the London Mathematical Society 5587:Journal of the London Mathematical Society 5312:Semantic Techniques in Quantum Computation 5200: 4602:(Left, right, two-sided) ample semigroups. 4284: 4278: 4204: 3827:. One of the main results in the study of 3744:{\displaystyle (A,g)(B,h)=(A\wedge gB,gh)} 2431:{\displaystyle se\in E\Rightarrow s\in E.} 1400:reduces to restriction of mappings, i.e., 5670: 5548: 5420: 5376: 5310:. In Gay and, Simon; Mackie, Ian (eds.). 5008: 4777:(2nd ed.). CRC Press. p. 1528. 4588:of generalised inverse semigroups is the 4323: 4310: 4279: 4266: 4250: 4231: 4215: 4180: 4165: 4110: 4109: 4107: 4086: 4085: 4083: 4062: 4061: 4059: 4031: 4030: 4021: 4020: 4009: 3917: 3916: 3907: 3906: 3892: 3868: 3867: 3858: 3857: 3846: 3785: 3784: 3775: 3774: 3760: 3679: 3649: 3648: 3633: 3614: 3613: 3580: 3579: 3570: 3569: 3555: 3524: 3523: 3514: 3513: 3502: 3477: 3476: 3474: 3453: 3452: 3450: 3405: 3404: 3402: 3369: 3368: 3366: 3334: 3333: 3324: 3323: 3312: 3269: 3268: 3266: 3206: 3205: 3203: 3161: 3160: 3158: 3133: 3132: 3130: 3074: 3073: 3071: 3030: 3029: 3027: 2990: 2989: 2987: 2952: 2951: 2949: 2924: 2923: 2921: 2892: 2891: 2889: 2864: 2863: 2861: 2838: 2837: 2835: 2812: 2785: 2784: 2782: 2749: 2748: 2746: 2722: 2721: 2719: 2694: 2693: 2691: 2666: 2665: 2663: 2622: 2606: 2585: 2554: 2526: 2399: 2349: 2249: 2245: 2207: 2184:-unitary inverse semigroups (see below). 2067: 2041: 2019: 2015: 2010: 1983: 1955: 1951: 1938: 1934: 1923: 1919: 1914: 1818: 1812: 1811: 1808: 1552: 1514: 1508: 1507: 1506: 1504: 1471: 1465: 1464: 1463: 1461: 1359: 1343: 1325: 1263: 1176: 1115: 824: 805: 791: 785: 784: 783: 764: 745: 734: 728: 727: 726: 721: 685: 684: 682: 646: 645: 643: 610: 609: 607: 586: 585: 583: 558: 557: 555: 534: 533: 531: 492:has a unique inverse, in the above sense. 333: 327: 326: 323: 318:. Under this composition, the collection 269: 260: 212: 5338:Clifford, A. H.; Preston, G. B. (1967). 5263: 4838: 1396:. In a symmetric inverse semigroup, the 954: 5759: 4774:CRC Concise Encyclopedia of Mathematics 4763: 4142:of the free inverse semigroup on a set 4000:-theorem has been used to characterize 1978:Of particular interest is the relation 353:forms an inverse semigroup, called the 5763: 5227: 5215: 5145: 5133: 5109: 5097: 5085: 5061: 5024: 4970: 4923: 4863: 4826: 4822: 4809: 4797: 4138:is possible for inverse semigroups. A 2104:is a congruence and, in fact, it is a 5752: 5308:"The Structure of Partial Isometries" 5251: 5239: 5196: 5184: 5121: 5073: 5057: 4958: 4946: 4934: 4911: 4899: 4887: 4875: 4851: 4420:can be defined by the conditions (1) 4416:As noted above, an inverse semigroup 4412:Generalisations of inverse semigroups 2502:. Then the following are equivalent: 7: 4625:is simply a category in which every 4398:Ehresmann–Schein–Nambooripad Theorem 3971:-class has a maximal element. Every 2108:, meaning that the factor semigroup 188:be partial transformations of a set 4146:may be obtained by considering the 3959:An inverse semigroup is said to be 2441:One further characterisation of an 5440:"(Weakly) left E-ample semigroups" 5341:The Algebraic Theory of Semigroups 5064:and, independently, Preston 1954c. 4506:is an inverse semigroup, for each 4054:-inverse semigroup if and only if 2769:, that is, every pair of elements 1998:, defined on an inverse semigroup 1827:{\displaystyle {\mathcal {I}}_{S}} 1792:is an inverse semigroup, then the 1518:{\displaystyle \,{\mathcal {R}}\,} 1475:{\displaystyle \,{\mathcal {L}}\,} 473:inverse monoid), is, of course, a 342:{\displaystyle {\mathcal {I}}_{X}} 25: 5267: 1888:Congruences on inverse semigroups 1218:for some (in general, different) 5466:Fundamentals of Semigroup Theory 5285:. World Scientific. p. 55. 4371:Connections with category theory 3963:-inverse if every element has a 3989:Every inverse semigroup has an 3831:-unitary inverse semigroups is 1930: 1410:if, and only if, the domain of 779: 301:composition of binary relations 5732:. Novaya Seriya (in Russian). 5709:(1952). "Generalised groups". 4821:First a short announcement in 4538:Generalised inverse semigroups 4363:Any free inverse semigroup is 4320: 4297: 4280: 4275: 4205: 4198: 4170: 4148:free semigroup with involution 4119:{\displaystyle {\mathcal {X}}} 4095:{\displaystyle {\mathcal {X}}} 4071:{\displaystyle {\mathcal {Y}}} 4037: 4011: 3944:-unitary inverse semigroup is 3923: 3897: 3874: 3848: 3791: 3765: 3738: 3714: 3708: 3696: 3693: 3681: 3607: 3595: 3586: 3560: 3530: 3504: 3486:{\displaystyle {\mathcal {Y}}} 3462:{\displaystyle {\mathcal {Y}}} 3414:{\displaystyle {\mathcal {Y}}} 3378:{\displaystyle {\mathcal {X}}} 3340: 3314: 3278:{\displaystyle {\mathcal {X}}} 3215:{\displaystyle {\mathcal {X}}} 3170:{\displaystyle {\mathcal {X}}} 3142:{\displaystyle {\mathcal {X}}} 3083:{\displaystyle {\mathcal {X}}} 3039:{\displaystyle {\mathcal {X}}} 2999:{\displaystyle {\mathcal {Y}}} 2961:{\displaystyle {\mathcal {Y}}} 2933:{\displaystyle {\mathcal {X}}} 2901:{\displaystyle {\mathcal {X}}} 2873:{\displaystyle {\mathcal {Y}}} 2847:{\displaystyle {\mathcal {Y}}} 2794:{\displaystyle {\mathcal {Y}}} 2758:{\displaystyle {\mathcal {Y}}} 2731:{\displaystyle {\mathcal {X}}} 2703:{\displaystyle {\mathcal {Y}}} 2675:{\displaystyle {\mathcal {X}}} 2596: 2413: 2363: 2271: 2265: 2253: 2236: 2230: 2023: 1942: 1563: 1414:is contained in the domain of 1336: 1286: 1187: 1126: 858:Examples of inverse semigroups 795: 738: 694:{\displaystyle {\mathcal {R}}} 655:{\displaystyle {\mathcal {L}}} 619:{\displaystyle {\mathcal {R}}} 595:{\displaystyle {\mathcal {L}}} 574:-class contains precisely one 567:{\displaystyle {\mathcal {R}}} 543:{\displaystyle {\mathcal {L}}} 253: 229: 1: 5431:10.1090/S0002-9939-98-04575-4 5242:, Section 2.4 & Chapter 6 5199:, Theorem 5.9.2. Originally, 4742:Special classes of semigroups 4549:generalised inverse semigroup 3671:together with multiplication 2649:McAlister's Covering Theorem. 2491:be an inverse semigroup with 375:. For example, just as every 5060:, Theorem 5.1.7 Originally, 4689:theoretical computer science 4134:A construction similar to a 3887:be a McAlister triple. Then 5749:Clifford & Preston 1967 5468:. Oxford: Clarendon Press. 5046:Clifford & Preston 1967 4983:Clifford & Preston 1967 4771:Weisstein, Eric W. (2002). 4680:. The category of sets and 4404:with respect to its (dual) 3493:have nonempty intersection. 2686:, with ordering ≤, and let 2445:-unitary inverse semigroup 2294:-unitary inverse semigroups 2148:is any other congruence on 356:symmetric inverse semigroup 123:Viktor Vladimirovich Wagner 5832: 5531:McAlister, D. B. (1974b). 5164:. CRC Press. p. 248. 5031:: CS1 maint: postscript ( 4642:has a generalized inverse 4555:form a normal band, i.e., 4489:Locally inverse semigroups 2090:{\displaystyle c\leq a,b.} 1774:, which is an analogue of 499:has at least one inverse ( 395:The inverse of an element 5791:10.1017/S0013091512000211 5378:10.1017/S0013091500016230 5019:10.1007/s00233-017-9858-5 4676:. An inverse category is 3975:-inverse semigroup is an 3046:(on the left), such that 2738:with the properties that 1884:is an inverse semigroup. 1092:The natural partial order 846:Unless stated otherwise, 713:in an inverse semigroup: 5770:Linckelmann, M. (2012). 5641:10.1112/jlms/s1-29.4.411 5620:10.1112/jlms/s1-29.4.404 5599:10.1112/jlms/s1-29.4.396 5359:Fountain, J. B. (1979). 4078:is a principal ideal of 2654:Central to the study of 2191:on an inverse semigroup 2174:minimum group congruence 2144:is a group, that is, if 2124:is an inverse semigroup 1617:) is finite and forms a 880:is an inverse semigroup. 399:of an inverse semigroup 35:(occasionally called an 5730:Matematicheskii Sbornik 5279:Grandis, Marco (2012). 5158:Grillet, P. A. (1995). 4130:Free inverse semigroups 2820:{\displaystyle \wedge } 1991:{\displaystyle \sigma } 1786:Wagner–Preston Theorem. 47:in which every element 5483:Lawson, M. V. (1998). 4914:, Proposition 5.1.2(1) 4890:, Proposition 5.1.2(1) 4684:is the prime example. 4339: 4120: 4096: 4072: 4044: 3930: 3881: 3839:McAlister's P-Theorem. 3798: 3745: 3662: 3537: 3487: 3463: 3415: 3379: 3347: 3279: 3216: 3171: 3143: 3084: 3040: 3000: 2962: 2934: 2902: 2874: 2848: 2821: 2795: 2759: 2732: 2704: 2676: 2638: 2571:compatibility relation 2563: 2535: 2432: 2382: 2281: 2091: 2056: 2055:{\displaystyle c\in S} 2030: 1992: 1969: 1828: 1772:Wagner–Preston Theorem 1585: 1519: 1476: 1375: 1308: 1209: 1148: 837: 695: 656: 620: 596: 568: 544: 511:commute (that is, the 343: 307:, so he introduced an 274: 147:partial transformation 5699:10.1007/s002330010132 5388:Mathematische Annalen 5361:"Adequate semigroups" 4534:forms a subsemigroup. 4340: 4121: 4097: 4073: 4045: 3948:to one of this type. 3931: 3882: 3833:McAlister's P-Theorem 3799: 3746: 3663: 3538: 3488: 3464: 3416: 3380: 3348: 3280: 3217: 3172: 3144: 3085: 3041: 3001: 2963: 2935: 2903: 2875: 2849: 2822: 2796: 2760: 2733: 2705: 2684:partially ordered set 2677: 2639: 2564: 2562:{\displaystyle \sim } 2536: 2534:{\displaystyle \sim } 2449:is the following: if 2433: 2383: 2282: 2100:It can be shown that 2092: 2057: 2031: 1993: 1970: 1829: 1586: 1520: 1477: 1376: 1309: 1210: 1149: 1096:An inverse semigroup 838: 696: 657: 621: 597: 569: 545: 379:can be embedded in a 344: 275: 5811:Algebraic structures 5796:Open access preprint 5566:Petrich, M. (1984). 5487:. World Scientific. 4164: 4106: 4082: 4058: 4008: 3891: 3845: 3759: 3678: 3554: 3501: 3473: 3449: 3401: 3365: 3311: 3265: 3202: 3157: 3129: 3070: 3026: 2986: 2948: 2920: 2888: 2860: 2854:(with respect to ≤); 2834: 2811: 2803:greatest lower bound 2781: 2745: 2718: 2690: 2662: 2584: 2553: 2525: 2398: 2348: 2206: 2066: 2040: 2009: 1982: 1913: 1904:equivalence relation 1807: 1551: 1503: 1460: 1324: 1262: 1233:can be taken to be 1175: 1114: 720: 681: 642: 606: 582: 554: 530: 444:. An inverse monoid 322: 309:empty transformation 211: 5722:English translation 5136:, Proposition 2.4.3 4973:, Proposition 3.2.3 4937:, Proposition 5.2.1 4517:Orthodox semigroups 4406:Alexandrov topology 4152:taking the quotient 3955:-inverse semigroups 2519:is idempotent pure; 957: 403:is usually written 37:inversion semigroup 5672:10.1007/BF02676643 5568:Inverse semigroups 5400:10.1007/BF01597390 4850:See, for example, 4717:Partial symmetries 4702:Orthodox semigroup 4682:partial bijections 4445:Regular semigroups 4392:, in the sense of 4390:inductive groupoid 4335: 4126:is a semilattice. 4116: 4092: 4068: 4040: 3926: 3877: 3794: 3741: 3658: 3533: 3483: 3459: 3411: 3375: 3343: 3275: 3212: 3167: 3149:, there exists an 3139: 3080: 3036: 2996: 2958: 2930: 2898: 2870: 2844: 2817: 2791: 2755: 2728: 2700: 2672: 2634: 2559: 2531: 2428: 2378: 2277: 2087: 2052: 2026: 1988: 1965: 1824: 1581: 1515: 1472: 1371: 1304: 1205: 1144: 956:Inverse semigroup 955: 885:bicyclic semigroup 833: 691: 652: 616: 592: 564: 540: 371:is the archetypal 339: 270: 139:partial bijections 92:partial symmetries 66:in the sense that 5351:978-0-8218-0272-4 5321:978-0-521-51374-6 5292:978-981-4407-06-9 5171:978-0-8247-9662-4 4784:978-1-4200-3522-3 4752:Nambooripad order 4732:Green's relations 4722:Regular semigroup 4542:regular semigroup 4530:if its subset of 4521:regular semigroup 4493:regular semigroup 4426:regular semigroup 4156:Vagner congruence 3385:, there exists a 3232:if, and only if, 3100:if, and only if, 2767:lower semilattice 2168:. The congruence 1767:of that element. 1708:is a morphism if 1653:) is an infinite 1441:Green's relations 1432:in the domain of 1089: 1088: 887:is inverse, with 711:Green's relations 628:Green's relations 550:-class and every 505:regular semigroup 495:Every element of 488:Every element of 365:converse relation 88:regular semigroup 33:inverse semigroup 16:(Redirected from 5823: 5816:Semigroup theory 5794: 5776: 5737: 5720: 5702: 5676: 5674: 5644: 5623: 5602: 5581: 5562: 5552: 5527: 5498: 5479: 5457: 5455: 5454: 5448: 5442:. Archived from 5434: 5424: 5422:funct-an/9511003 5403: 5382: 5380: 5355: 5326: 5325: 5303: 5297: 5296: 5276: 5270: 5261: 5255: 5249: 5243: 5237: 5231: 5225: 5219: 5213: 5204: 5194: 5188: 5187:, pp. 193–4 5182: 5176: 5175: 5155: 5149: 5143: 5137: 5131: 5125: 5119: 5113: 5107: 5101: 5095: 5089: 5083: 5077: 5071: 5065: 5055: 5049: 5043: 5037: 5036: 5030: 5022: 5012: 4992: 4986: 4980: 4974: 4968: 4962: 4956: 4950: 4949:, pp. 152–3 4944: 4938: 4932: 4926: 4921: 4915: 4909: 4903: 4897: 4891: 4885: 4879: 4873: 4867: 4861: 4855: 4848: 4842: 4836: 4830: 4819: 4813: 4806: 4800: 4795: 4789: 4788: 4768: 4675: 4665: 4655: 4641: 4623:inverse category 4613:Inverse category 4564: 4484: 4344: 4342: 4341: 4336: 4328: 4327: 4318: 4317: 4283: 4274: 4273: 4258: 4257: 4239: 4238: 4223: 4222: 4188: 4187: 4125: 4123: 4122: 4117: 4115: 4114: 4101: 4099: 4098: 4093: 4091: 4090: 4077: 4075: 4074: 4069: 4067: 4066: 4049: 4047: 4046: 4041: 4036: 4035: 4026: 4025: 3993:-inverse cover. 3935: 3933: 3932: 3927: 3922: 3921: 3912: 3911: 3886: 3884: 3883: 3878: 3873: 3872: 3863: 3862: 3826: 3803: 3801: 3800: 3795: 3790: 3789: 3780: 3779: 3750: 3748: 3747: 3742: 3667: 3665: 3664: 3659: 3654: 3653: 3641: 3640: 3619: 3618: 3585: 3584: 3575: 3574: 3545:McAlister triple 3542: 3540: 3539: 3534: 3529: 3528: 3519: 3518: 3492: 3490: 3489: 3484: 3482: 3481: 3468: 3466: 3465: 3460: 3458: 3457: 3430: 3420: 3418: 3417: 3412: 3410: 3409: 3384: 3382: 3381: 3376: 3374: 3373: 3352: 3350: 3349: 3344: 3339: 3338: 3329: 3328: 3302: 3284: 3282: 3281: 3276: 3274: 3273: 3241: 3231: 3221: 3219: 3218: 3213: 3211: 3210: 3186: 3176: 3174: 3173: 3168: 3166: 3165: 3148: 3146: 3145: 3140: 3138: 3137: 3109: 3099: 3089: 3087: 3086: 3081: 3079: 3078: 3045: 3043: 3042: 3037: 3035: 3034: 3005: 3003: 3002: 2997: 2995: 2994: 2977: 2967: 2965: 2964: 2959: 2957: 2956: 2939: 2937: 2936: 2931: 2929: 2928: 2907: 2905: 2904: 2899: 2897: 2896: 2879: 2877: 2876: 2871: 2869: 2868: 2853: 2851: 2850: 2845: 2843: 2842: 2826: 2824: 2823: 2818: 2800: 2798: 2797: 2792: 2790: 2789: 2764: 2762: 2761: 2756: 2754: 2753: 2737: 2735: 2734: 2729: 2727: 2726: 2709: 2707: 2706: 2701: 2699: 2698: 2681: 2679: 2678: 2673: 2671: 2670: 2643: 2641: 2640: 2635: 2630: 2629: 2614: 2613: 2568: 2566: 2565: 2560: 2540: 2538: 2537: 2532: 2437: 2435: 2434: 2429: 2387: 2385: 2384: 2379: 2286: 2284: 2283: 2278: 2164:is contained in 2106:group congruence 2096: 2094: 2093: 2088: 2061: 2059: 2058: 2053: 2035: 2033: 2032: 2027: 1997: 1995: 1994: 1989: 1974: 1972: 1971: 1966: 1833: 1831: 1830: 1825: 1823: 1822: 1817: 1816: 1776:Cayley's theorem 1759:The homomorphic 1752: 1726: 1590: 1588: 1587: 1582: 1528: 1524: 1522: 1521: 1516: 1513: 1512: 1495:. Similarly, if 1494: 1481: 1479: 1478: 1473: 1470: 1469: 1452: 1427: 1409: 1380: 1378: 1377: 1372: 1367: 1366: 1351: 1350: 1313: 1311: 1310: 1305: 1214: 1212: 1211: 1206: 1168:. Equivalently, 1153: 1151: 1150: 1145: 958: 951: 941: 919:Brandt semigroup 906: 842: 840: 839: 834: 832: 831: 813: 812: 790: 789: 772: 771: 753: 752: 733: 732: 700: 698: 697: 692: 690: 689: 661: 659: 658: 653: 651: 650: 625: 623: 622: 617: 615: 614: 601: 599: 598: 593: 591: 590: 573: 571: 570: 565: 563: 562: 549: 547: 546: 541: 539: 538: 460: 425:. In an inverse 424: 348: 346: 345: 340: 338: 337: 332: 331: 316:binary operation 279: 277: 276: 271: 268: 267: 129:in 1952, and by 85: 75: 21: 18:Inverse category 5831: 5830: 5826: 5825: 5824: 5822: 5821: 5820: 5801: 5800: 5774: 5769: 5751:, Chapter 7 or 5744: 5742:Further reading 5727: 5705: 5686:Semigroup Forum 5679: 5658:Semigroup Forum 5647: 5626: 5605: 5584: 5578: 5565: 5550:10.2307/1997032 5530: 5516:10.2307/1996831 5501: 5495: 5482: 5476: 5460: 5452: 5450: 5446: 5437: 5406: 5385: 5358: 5352: 5337: 5334: 5329: 5322: 5305: 5304: 5300: 5293: 5278: 5277: 5273: 5262: 5258: 5250: 5246: 5238: 5234: 5226: 5222: 5214: 5207: 5201:McAlister 1974a 5195: 5191: 5183: 5179: 5172: 5157: 5156: 5152: 5148:, Theorem 2.4.6 5144: 5140: 5132: 5128: 5120: 5116: 5108: 5104: 5100:, Theorem 2.4.1 5096: 5092: 5084: 5080: 5072: 5068: 5056: 5052: 5044: 5040: 5023: 4997:Semigroup Forum 4994: 4993: 4989: 4981: 4977: 4969: 4965: 4957: 4953: 4945: 4941: 4933: 4929: 4922: 4918: 4910: 4906: 4902:, Theorem 5.1.1 4898: 4894: 4886: 4882: 4874: 4870: 4862: 4858: 4849: 4845: 4837: 4833: 4820: 4816: 4807: 4803: 4796: 4792: 4785: 4770: 4769: 4765: 4761: 4756: 4737:Category theory 4697: 4667: 4657: 4643: 4629: 4615: 4556: 4500:locally inverse 4476: 4414: 4394:category theory 4373: 4319: 4306: 4262: 4246: 4227: 4211: 4176: 4162: 4161: 4132: 4104: 4103: 4080: 4079: 4056: 4055: 4006: 4005: 3957: 3889: 3888: 3843: 3842: 3805: 3757: 3756: 3676: 3675: 3629: 3552: 3551: 3499: 3498: 3471: 3470: 3447: 3446: 3422: 3399: 3398: 3363: 3362: 3309: 3308: 3286: 3263: 3262: 3233: 3223: 3200: 3199: 3178: 3155: 3154: 3127: 3126: 3101: 3091: 3068: 3067: 3024: 3023: 2984: 2983: 2969: 2946: 2945: 2918: 2917: 2908:, that is, for 2886: 2885: 2858: 2857: 2832: 2831: 2809: 2808: 2779: 2778: 2743: 2742: 2716: 2715: 2688: 2687: 2660: 2659: 2644:are idempotent. 2618: 2602: 2582: 2581: 2551: 2550: 2523: 2522: 2396: 2395: 2346: 2345: 2296: 2204: 2203: 2197:idempotent pure 2064: 2063: 2038: 2037: 2036:there exists a 2007: 2006: 1980: 1979: 1911: 1910: 1890: 1810: 1805: 1804: 1740: 1709: 1675: 1631:totally ordered 1549: 1548: 1540:), the natural 1501: 1500: 1496: 1486: 1458: 1457: 1444: 1443:as follows: if 1419: 1401: 1355: 1339: 1322: 1321: 1260: 1259: 1173: 1172: 1112: 1111: 1094: 943: 933: 888: 860: 820: 801: 760: 741: 718: 717: 679: 678: 640: 639: 604: 603: 580: 579: 552: 551: 528: 527: 449: 412: 411:, for example, 393: 381:symmetric group 369:symmetric group 359:(or monoid) on 325: 320: 319: 256: 209: 208: 176:are subsets of 119: 77: 67: 23: 22: 15: 12: 11: 5: 5829: 5827: 5819: 5818: 5813: 5803: 5802: 5799: 5798: 5767: 5756: 5743: 5740: 5739: 5738: 5736:(74): 545–632. 5725: 5715:(in Russian). 5703: 5677: 5645: 5624: 5614:(4): 404–411. 5603: 5593:(4): 396–403. 5582: 5576: 5563: 5528: 5499: 5493: 5480: 5474: 5458: 5435: 5415:(12): 3481–4. 5404: 5383: 5371:(2): 113–125. 5356: 5350: 5333: 5330: 5328: 5327: 5320: 5298: 5291: 5271: 5256: 5244: 5232: 5220: 5205: 5189: 5177: 5170: 5150: 5138: 5126: 5114: 5102: 5090: 5078: 5066: 5050: 5048:, Theorem 7.36 5038: 5003:(2): 203–240. 4987: 4975: 4963: 4951: 4939: 4927: 4916: 4904: 4892: 4880: 4868: 4856: 4843: 4831: 4814: 4801: 4790: 4783: 4762: 4760: 4757: 4755: 4754: 4749: 4744: 4739: 4734: 4729: 4724: 4719: 4714: 4709: 4704: 4698: 4696: 4693: 4614: 4611: 4610: 4609: 4606: 4603: 4600: 4582: 4581: 4535: 4514: 4486: 4467:, there is an 4428:, and (2) the 4413: 4410: 4402:étale groupoid 4372: 4369: 4346: 4345: 4334: 4331: 4326: 4322: 4316: 4313: 4309: 4305: 4302: 4299: 4296: 4293: 4290: 4287: 4282: 4277: 4272: 4269: 4265: 4261: 4256: 4253: 4249: 4245: 4242: 4237: 4234: 4230: 4226: 4221: 4218: 4214: 4210: 4207: 4203: 4200: 4197: 4194: 4191: 4186: 4183: 4179: 4175: 4172: 4169: 4131: 4128: 4113: 4089: 4065: 4039: 4034: 4029: 4024: 4019: 4016: 4013: 3956: 3950: 3925: 3920: 3915: 3910: 3905: 3902: 3899: 3896: 3876: 3871: 3866: 3861: 3856: 3853: 3850: 3793: 3788: 3783: 3778: 3773: 3770: 3767: 3764: 3753: 3752: 3740: 3737: 3734: 3731: 3728: 3725: 3722: 3719: 3716: 3713: 3710: 3707: 3704: 3701: 3698: 3695: 3692: 3689: 3686: 3683: 3669: 3668: 3657: 3652: 3647: 3644: 3639: 3636: 3632: 3628: 3625: 3622: 3617: 3612: 3609: 3606: 3603: 3600: 3597: 3594: 3591: 3588: 3583: 3578: 3573: 3568: 3565: 3562: 3559: 3532: 3527: 3522: 3517: 3512: 3509: 3506: 3497:Such a triple 3495: 3494: 3480: 3456: 3432: 3408: 3372: 3342: 3337: 3332: 3327: 3322: 3319: 3316: 3305: 3304: 3272: 3243: 3209: 3188: 3164: 3136: 3111: 3077: 3033: 3008: 3007: 2993: 2955: 2927: 2895: 2867: 2855: 2841: 2816: 2788: 2752: 2725: 2697: 2669: 2646: 2645: 2633: 2628: 2625: 2621: 2617: 2612: 2609: 2605: 2601: 2598: 2595: 2592: 2589: 2558: 2547: 2546: 2530: 2520: 2514: 2439: 2438: 2427: 2424: 2421: 2418: 2415: 2412: 2409: 2406: 2403: 2391:Equivalently, 2389: 2388: 2377: 2374: 2371: 2368: 2365: 2362: 2359: 2356: 2353: 2295: 2289: 2288: 2287: 2276: 2273: 2270: 2267: 2264: 2261: 2258: 2255: 2252: 2248: 2244: 2241: 2238: 2235: 2232: 2229: 2226: 2223: 2220: 2217: 2214: 2211: 2172:is called the 2160:a group, then 2132:congruence on 2098: 2097: 2086: 2083: 2080: 2077: 2074: 2071: 2051: 2048: 2045: 2025: 2022: 2018: 2014: 1987: 1976: 1975: 1964: 1961: 1958: 1954: 1950: 1947: 1944: 1941: 1937: 1933: 1929: 1926: 1922: 1918: 1889: 1886: 1866:representation 1859: 1858: 1821: 1815: 1674: 1671: 1594:so, since the 1592: 1591: 1580: 1577: 1574: 1571: 1568: 1565: 1562: 1559: 1556: 1511: 1468: 1382: 1381: 1370: 1365: 1362: 1358: 1354: 1349: 1346: 1342: 1338: 1335: 1332: 1329: 1315: 1314: 1303: 1300: 1297: 1294: 1291: 1288: 1285: 1282: 1279: 1276: 1273: 1270: 1267: 1216: 1215: 1204: 1201: 1198: 1195: 1192: 1189: 1186: 1183: 1180: 1155: 1154: 1143: 1140: 1137: 1134: 1131: 1128: 1125: 1122: 1119: 1093: 1090: 1087: 1086: 1083: 1080: 1077: 1074: 1071: 1065: 1064: 1061: 1058: 1055: 1052: 1049: 1043: 1042: 1039: 1036: 1033: 1030: 1027: 1021: 1020: 1017: 1014: 1011: 1008: 1005: 999: 998: 995: 992: 989: 986: 983: 977: 976: 973: 970: 967: 964: 961: 930: 929: 926:Munn semigroup 922: 915: 908: 881: 874: 859: 856: 844: 843: 830: 827: 823: 819: 816: 811: 808: 804: 800: 797: 794: 788: 782: 778: 775: 770: 767: 763: 759: 756: 751: 748: 744: 740: 737: 731: 725: 688: 673:, whilst the 649: 632: 631: 613: 589: 561: 537: 524: 493: 392: 389: 336: 330: 281: 280: 266: 263: 259: 255: 252: 249: 246: 243: 240: 237: 234: 231: 228: 225: 222: 219: 216: 135:United Kingdom 131:Gordon Preston 118: 115: 24: 14: 13: 10: 9: 6: 4: 3: 2: 5828: 5817: 5814: 5812: 5809: 5808: 5806: 5797: 5792: 5788: 5784: 5780: 5773: 5768: 5765: 5761: 5757: 5754: 5750: 5746: 5745: 5741: 5735: 5731: 5726: 5723: 5718: 5714: 5713: 5708: 5707:Wagner, V. V. 5704: 5700: 5696: 5692: 5688: 5687: 5682: 5681:Schein, B. M. 5678: 5673: 5668: 5664: 5660: 5659: 5654: 5650: 5649:Schein, B. M. 5646: 5642: 5638: 5634: 5630: 5625: 5621: 5617: 5613: 5609: 5604: 5600: 5596: 5592: 5588: 5583: 5579: 5573: 5569: 5564: 5560: 5556: 5551: 5546: 5542: 5538: 5534: 5529: 5525: 5521: 5517: 5513: 5509: 5505: 5500: 5496: 5490: 5486: 5481: 5477: 5471: 5467: 5463: 5459: 5449:on 2005-08-26 5445: 5441: 5436: 5432: 5428: 5423: 5418: 5414: 5410: 5405: 5401: 5397: 5393: 5390:(in German). 5389: 5384: 5379: 5374: 5370: 5366: 5362: 5357: 5353: 5347: 5343: 5342: 5336: 5335: 5331: 5323: 5317: 5313: 5309: 5302: 5299: 5294: 5288: 5284: 5283: 5275: 5272: 5269: 5265: 5264:Fountain 1979 5260: 5257: 5254:, p. 222 5253: 5248: 5245: 5241: 5236: 5233: 5229: 5224: 5221: 5218:, p. 230 5217: 5212: 5210: 5206: 5202: 5198: 5193: 5190: 5186: 5181: 5178: 5173: 5167: 5163: 5162: 5154: 5151: 5147: 5142: 5139: 5135: 5130: 5127: 5124:, p. 192 5123: 5118: 5115: 5111: 5106: 5103: 5099: 5094: 5091: 5087: 5082: 5079: 5075: 5070: 5067: 5063: 5059: 5054: 5051: 5047: 5042: 5039: 5034: 5028: 5021:Corollary 4.9 5020: 5016: 5011: 5006: 5002: 4998: 4991: 4988: 4985:, Theorem 7.5 4984: 4979: 4976: 4972: 4967: 4964: 4961:, p. 153 4960: 4955: 4952: 4948: 4943: 4940: 4936: 4931: 4928: 4925: 4920: 4917: 4913: 4908: 4905: 4901: 4896: 4893: 4889: 4884: 4881: 4878:, p. 149 4877: 4872: 4869: 4866:, p. 152 4865: 4860: 4857: 4853: 4847: 4844: 4840: 4839:Preston 1954a 4835: 4832: 4828: 4824: 4818: 4815: 4811: 4805: 4802: 4799: 4794: 4791: 4786: 4780: 4776: 4775: 4767: 4764: 4758: 4753: 4750: 4748: 4745: 4743: 4740: 4738: 4735: 4733: 4730: 4728: 4725: 4723: 4720: 4718: 4715: 4713: 4710: 4708: 4707:Biordered set 4705: 4703: 4700: 4699: 4694: 4692: 4690: 4685: 4683: 4679: 4674: 4670: 4664: 4660: 4654: 4650: 4646: 4640: 4636: 4632: 4628: 4624: 4620: 4612: 4607: 4604: 4601: 4598: 4597: 4596: 4593: 4591: 4587: 4579: 4575: 4571: 4568: 4563: 4559: 4554: 4550: 4546: 4543: 4539: 4536: 4533: 4529: 4525: 4522: 4518: 4515: 4512: 4509: 4505: 4501: 4497: 4494: 4490: 4487: 4483: 4479: 4474: 4470: 4466: 4462: 4458: 4454: 4451: 4447: 4446: 4442: 4441: 4440: 4437: 4435: 4431: 4427: 4423: 4419: 4411: 4409: 4407: 4403: 4399: 4395: 4391: 4387: 4383: 4379: 4370: 4368: 4366: 4361: 4359: 4355: 4351: 4332: 4324: 4314: 4311: 4307: 4303: 4300: 4294: 4291: 4288: 4285: 4270: 4267: 4263: 4259: 4254: 4251: 4247: 4243: 4240: 4235: 4232: 4228: 4224: 4219: 4216: 4212: 4208: 4201: 4195: 4192: 4189: 4184: 4181: 4177: 4173: 4160: 4159: 4158: 4157: 4153: 4149: 4145: 4141: 4137: 4129: 4127: 4053: 4027: 4017: 4014: 4003: 3999: 3994: 3992: 3988: 3984: 3982: 3978: 3974: 3970: 3966: 3962: 3954: 3951: 3949: 3947: 3943: 3939: 3913: 3903: 3900: 3894: 3864: 3854: 3851: 3840: 3836: 3834: 3830: 3824: 3820: 3817: 3813: 3809: 3781: 3771: 3768: 3762: 3735: 3732: 3729: 3726: 3723: 3720: 3717: 3711: 3705: 3702: 3699: 3690: 3687: 3684: 3674: 3673: 3672: 3645: 3642: 3637: 3634: 3630: 3626: 3623: 3620: 3610: 3604: 3601: 3598: 3589: 3576: 3566: 3563: 3557: 3550: 3549: 3548: 3546: 3520: 3510: 3507: 3445: 3441: 3437: 3433: 3429: 3425: 3396: 3392: 3388: 3360: 3356: 3355: 3354: 3330: 3320: 3317: 3301: 3297: 3293: 3289: 3260: 3256: 3252: 3248: 3244: 3240: 3236: 3230: 3226: 3197: 3193: 3189: 3185: 3181: 3152: 3124: 3120: 3116: 3112: 3108: 3104: 3098: 3094: 3065: 3061: 3057: 3053: 3049: 3048: 3047: 3021: 3017: 3013: 2981: 2976: 2972: 2943: 2915: 2911: 2883: 2856: 2829: 2814: 2807: 2804: 2776: 2772: 2768: 2741: 2740: 2739: 2713: 2685: 2657: 2652: 2650: 2631: 2626: 2623: 2619: 2615: 2610: 2607: 2603: 2599: 2593: 2590: 2587: 2580: 2579: 2578: 2577:, defined by 2576: 2572: 2556: 2544: 2528: 2521: 2518: 2515: 2512: 2508: 2505: 2504: 2503: 2501: 2497: 2494: 2490: 2486: 2482: 2480: 2476: 2472: 2468: 2464: 2460: 2456: 2452: 2448: 2444: 2425: 2422: 2419: 2416: 2410: 2407: 2404: 2401: 2394: 2393: 2392: 2375: 2372: 2369: 2366: 2360: 2357: 2354: 2351: 2344: 2343: 2342: 2340: 2336: 2332: 2328: 2324: 2320: 2316: 2312: 2309: 2305: 2301: 2293: 2290: 2274: 2268: 2262: 2259: 2256: 2250: 2246: 2242: 2239: 2233: 2227: 2224: 2221: 2218: 2215: 2212: 2209: 2202: 2201: 2200: 2198: 2194: 2190: 2187:A congruence 2185: 2183: 2179: 2175: 2171: 2167: 2163: 2159: 2155: 2151: 2147: 2143: 2139: 2135: 2131: 2127: 2123: 2119: 2115: 2111: 2107: 2103: 2084: 2081: 2078: 2075: 2072: 2069: 2049: 2046: 2043: 2020: 2016: 2012: 2005: 2004: 2003: 2001: 1985: 1962: 1959: 1956: 1952: 1948: 1945: 1939: 1935: 1931: 1927: 1924: 1920: 1916: 1909: 1908: 1907: 1905: 1901: 1898: 1894: 1887: 1885: 1883: 1879: 1873: 1871: 1867: 1864: 1857: 1853: 1849: 1845: 1841: 1837: 1836: 1835: 1819: 1802: 1798: 1795: 1791: 1787: 1783: 1781: 1777: 1773: 1768: 1766: 1762: 1758: 1754: 1751: 1748: 1744: 1738: 1734: 1730: 1725: 1721: 1717: 1713: 1707: 1703: 1699: 1696: 1692: 1688: 1684: 1680: 1672: 1670: 1668: 1664: 1660: 1656: 1652: 1648: 1644: 1640: 1636: 1632: 1628: 1624: 1620: 1616: 1612: 1607: 1605: 1601: 1597: 1578: 1575: 1572: 1569: 1566: 1560: 1557: 1554: 1547: 1546: 1545: 1543: 1542:partial order 1539: 1535: 1530: 1527: 1499: 1493: 1489: 1484: 1456: 1451: 1447: 1442: 1437: 1435: 1431: 1426: 1422: 1417: 1413: 1408: 1404: 1399: 1398:partial order 1395: 1391: 1390:partial order 1387: 1368: 1363: 1360: 1356: 1352: 1347: 1344: 1340: 1333: 1330: 1327: 1320: 1319: 1318: 1301: 1298: 1295: 1292: 1289: 1283: 1280: 1277: 1274: 1271: 1268: 1265: 1258: 1257: 1256: 1254: 1253:partial order 1249: 1247: 1244: 1240: 1236: 1232: 1228: 1224: 1221: 1202: 1199: 1196: 1193: 1190: 1184: 1181: 1178: 1171: 1170: 1169: 1167: 1163: 1160: 1141: 1138: 1135: 1132: 1129: 1123: 1120: 1117: 1110: 1109: 1108: 1106: 1105: 1104:partial order 1099: 1091: 1084: 1081: 1078: 1075: 1072: 1070: 1067: 1066: 1062: 1059: 1056: 1053: 1050: 1048: 1045: 1044: 1040: 1037: 1034: 1031: 1028: 1026: 1023: 1022: 1018: 1015: 1012: 1009: 1006: 1004: 1001: 1000: 996: 993: 990: 987: 984: 982: 979: 978: 974: 971: 968: 965: 962: 960: 959: 953: 950: 946: 940: 936: 927: 923: 920: 916: 913: 909: 904: 900: 896: 892: 886: 882: 879: 875: 872: 868: 865: 862: 861: 857: 855: 853: 849: 828: 825: 821: 817: 814: 809: 806: 802: 798: 792: 780: 776: 773: 768: 765: 761: 757: 754: 749: 746: 742: 735: 723: 716: 715: 714: 712: 708: 704: 676: 672: 669: 665: 637: 629: 577: 525: 522: 518: 514: 510: 506: 502: 498: 494: 491: 487: 486: 485: 483: 478: 476: 472: 468: 464: 459: 456: 452: 447: 443: 439: 436: 432: 428: 423: 420: 416: 410: 406: 402: 398: 390: 388: 386: 382: 378: 374: 370: 366: 362: 358: 357: 352: 334: 317: 314: 310: 306: 302: 298: 294: 290: 286: 264: 261: 257: 250: 247: 244: 241: 238: 235: 232: 226: 223: 220: 217: 214: 207: 206: 205: 203: 199: 195: 191: 187: 183: 179: 175: 171: 167: 163: 159: 155: 151: 148: 144: 140: 136: 132: 128: 124: 116: 114: 112: 108: 104: 100: 95: 93: 89: 84: 80: 74: 70: 65: 61: 58: 55:has a unique 54: 50: 46: 42: 38: 34: 30: 19: 5782: 5778: 5760:Petrich 1984 5755:, Chapter 5. 5733: 5729: 5719:: 1119–1122. 5716: 5710: 5690: 5684: 5662: 5656: 5635:(4): 411–9. 5632: 5628: 5611: 5607: 5590: 5586: 5567: 5540: 5536: 5507: 5503: 5484: 5465: 5462:Howie, J. M. 5451:. Retrieved 5447:(Postscript) 5444:the original 5412: 5408: 5391: 5387: 5368: 5364: 5340: 5311: 5301: 5281: 5274: 5259: 5247: 5235: 5223: 5192: 5180: 5160: 5153: 5141: 5129: 5117: 5112:, p. 65 5105: 5093: 5088:, p. 62 5081: 5076:, p. 22 5069: 5053: 5041: 5027:cite journal 5000: 4996: 4990: 4978: 4966: 4954: 4942: 4930: 4919: 4907: 4895: 4883: 4871: 4859: 4846: 4834: 4817: 4804: 4793: 4773: 4766: 4747:Weak inverse 4686: 4672: 4668: 4662: 4658: 4652: 4648: 4644: 4638: 4634: 4630: 4622: 4616: 4594: 4590:intersection 4583: 4577: 4573: 4569: 4561: 4557: 4548: 4547:is called a 4544: 4537: 4527: 4523: 4516: 4510: 4503: 4499: 4495: 4488: 4481: 4477: 4472: 4468: 4464: 4460: 4456: 4452: 4443: 4438: 4433: 4421: 4417: 4415: 4397: 4385: 4381: 4377: 4374: 4364: 4362: 4350:word problem 4347: 4155: 4143: 4140:presentation 4133: 4051: 4001: 3997: 3996:McAlister's 3995: 3990: 3986: 3985: 3976: 3972: 3968: 3964: 3960: 3958: 3952: 3941: 3937: 3838: 3837: 3832: 3828: 3822: 3818: 3815: 3811: 3807: 3754: 3670: 3544: 3543:is called a 3496: 3443: 3439: 3435: 3427: 3423: 3394: 3390: 3386: 3358: 3306: 3299: 3295: 3291: 3287: 3258: 3254: 3250: 3246: 3238: 3234: 3228: 3224: 3195: 3191: 3183: 3179: 3150: 3122: 3118: 3114: 3106: 3102: 3096: 3092: 3063: 3059: 3055: 3051: 3011: 3009: 2979: 2974: 2970: 2941: 2913: 2909: 2827: 2805: 2774: 2770: 2655: 2653: 2648: 2647: 2574: 2570: 2548: 2542: 2516: 2510: 2506: 2499: 2495: 2488: 2484: 2483: 2478: 2474: 2470: 2466: 2462: 2458: 2454: 2450: 2446: 2442: 2440: 2390: 2338: 2334: 2330: 2326: 2325:if, for all 2322: 2318: 2310: 2303: 2299: 2297: 2291: 2196: 2192: 2188: 2186: 2181: 2177: 2173: 2169: 2165: 2161: 2157: 2153: 2149: 2145: 2141: 2137: 2133: 2129: 2125: 2121: 2117: 2113: 2109: 2101: 2099: 1999: 1977: 1899: 1896: 1891: 1881: 1877: 1874: 1869: 1860: 1855: 1851: 1847: 1843: 1839: 1800: 1796: 1789: 1785: 1784: 1771: 1769: 1756: 1755: 1749: 1746: 1742: 1736: 1732: 1728: 1723: 1719: 1715: 1711: 1705: 1701: 1697: 1690: 1686: 1682: 1679:homomorphism 1676: 1666: 1662: 1658: 1650: 1646: 1634: 1633:by ≤), then 1626: 1622: 1614: 1610: 1608: 1603: 1599: 1593: 1537: 1533: 1531: 1525: 1497: 1491: 1487: 1482: 1454: 1449: 1445: 1438: 1433: 1429: 1424: 1420: 1415: 1411: 1406: 1402: 1383: 1316: 1251:The natural 1250: 1245: 1242: 1238: 1234: 1230: 1226: 1222: 1217: 1165: 1161: 1156: 1101: 1100:possesses a 1097: 1095: 1068: 1046: 1024: 1002: 980: 948: 944: 938: 934: 931: 902: 898: 894: 890: 870: 851: 847: 845: 706: 702: 670: 667: 663: 633: 516: 500: 496: 489: 481: 479: 470: 466: 462: 457: 454: 450: 445: 437: 434: 430: 421: 418: 414: 404: 400: 396: 394: 360: 354: 350: 308: 297:pseudogroups 292: 287:denotes the 284: 282: 197: 193: 189: 185: 181: 177: 173: 169: 165: 161: 153: 149: 127:Soviet Union 120: 110: 106: 105:rather than 102: 98: 96: 82: 78: 72: 68: 63: 59: 56: 52: 48: 40: 36: 32: 26: 5764:Lawson 1998 5693:: 149–158. 5665:: 189–200. 5543:: 351–370. 5510:: 227–244. 5394:: 768–780. 5228:Lawson 1998 5216:Lawson 1998 5146:Lawson 1998 5134:Lawson 1998 5110:Lawson 1998 5098:Lawson 1998 5086:Lawson 1998 5062:Wagner 1952 4971:Lawson 1998 4924:Wagner 1952 4864:Schein 2002 4827:Wagner 1953 4823:Wagner 1952 4810:Schein 1981 4798:Lawson 1998 4727:Semilattice 4712:Pseudogroup 4567:idempotents 4553:idempotents 4532:idempotents 4430:idempotents 3981:M.V. Lawson 3307:The triple 2882:order ideal 2493:semilattice 2465:, for some 2315:idempotents 2308:semilattice 1893:Congruences 1834:, given by 1596:idempotents 1229:. In fact, 928:is inverse. 921:is inverse. 914:is inverse. 912:semilattice 626:are two of 521:semilattice 513:idempotents 509:idempotents 313:associative 291:under  31:theory, an 5805:Categories 5753:Howie 1995 5577:0471875457 5494:9810233167 5475:0198511949 5453:2006-08-28 5438:Gould, V. 5332:References 5252:Howie 1995 5240:Howie 1995 5197:Howie 1995 5185:Howie 1995 5122:Howie 1995 5074:Howie 1995 5058:Howie 1995 5010:1510.04117 4959:Howie 1995 4947:Howie 1995 4935:Howie 1995 4912:Howie 1995 4900:Howie 1995 4888:Howie 1995 4876:Howie 1995 4852:Gołab 1939 4656:such that 4619:categories 4565:, for all 4508:idempotent 4475:such that 4367:-inverse. 4358:Munn trees 4354:W. D. Munn 4136:free group 3946:isomorphic 3421:such that 3357:for every 3177:such that 2195:is called 2136:such that 1897:congruence 1727:, for all 1428:, for all 1394:idempotent 1220:idempotent 1159:idempotent 867:bijections 701:-class of 675:idempotent 662:-class of 636:idempotent 576:idempotent 461:, for all 442:idempotent 391:The basics 5570:. Wiley. 4450:semigroup 4312:− 4304:∪ 4295:∈ 4268:− 4252:− 4233:− 4217:− 4182:− 3721:∧ 3646:∈ 3635:− 3621:× 3611:∈ 3121:and each 3113:for each 2815:∧ 2624:− 2608:− 2597:⟺ 2591:∼ 2557:∼ 2529:∼ 2513:-unitary; 2420:∈ 2414:⇒ 2408:∈ 2370:∈ 2364:⟹ 2358:∈ 2260:∈ 2254:⟹ 2247:ρ 2225:∈ 2213:∈ 2073:≤ 2047:∈ 2024:⟺ 2017:σ 1986:σ 1953:ρ 1943:⟹ 1936:ρ 1921:ρ 1564:⟺ 1558:≤ 1544:becomes: 1361:− 1353:≤ 1345:− 1337:⟹ 1331:≤ 1296:≤ 1287:⟹ 1281:≤ 1269:≤ 1188:⟺ 1182:≤ 1157:for some 1127:⟺ 1121:≤ 869:on a set 826:− 807:− 796:⟺ 766:− 747:− 739:⟺ 471:unipotent 448:in which 305:empty set 262:− 258:α 251:β 248:⁡ 242:∩ 239:α 236:⁡ 224:β 221:α 218:⁡ 152:of a set 86:, i.e. a 45:semigroup 5651:(1981). 5464:(1995). 4695:See also 4678:selfdual 4647: : 4633: : 4627:morphism 4528:orthodox 3987:Theorem. 3434:for all 3257:and all 3245:for all 3190:for all 3058:and all 3050:for all 3010:Now let 2485:Theorem. 2333:and all 2130:smallest 1863:faithful 1794:function 1757:Theorem. 1695:function 1683:morphism 1102:natural 578:, where 387:below). 289:preimage 168:, where 158:function 5785:: 187. 5559:1997032 5524:1996831 5230:, 4.1.8 4551:if its 4457:regular 4154:by the 3393:and an 2978:, then 2569:is the 2473:, then 2323:unitary 2128:is the 1621:(i.e., 1485:, then 1388:, this 864:Partial 677:in the 638:in the 519:form a 133:in the 125:in the 117:Origins 57:inverse 5574:  5557:  5522:  5491:  5472:  5348:  5318:  5289:  5168:  4781:  4050:is an 3965:unique 3936:is an 2982:is in 2944:is in 2880:is an 2801:has a 2712:subset 2549:where 2477:is in 2453:is in 2306:(with 1902:is an 1780:groups 1643:groups 1241:to be 910:Every 876:Every 526:Every 507:) and 453:= 1 = 427:monoid 283:where 202:domain 180:. Let 101:  5775:(PDF) 5724:(PDF) 5555:JSTOR 5520:JSTOR 5417:arXiv 5268:Gould 5005:arXiv 4841:,b,c. 4759:Notes 4621:. An 4586:class 4424:is a 3814:) = ( 3755:Then 3294:) = ( 3018:that 3016:group 3014:be a 2940:, if 2765:is a 2710:be a 2682:be a 2457:and 2317:) is 2152:with 2062:with 1861:is a 1838:dom ( 1799:from 1765:image 1761:image 1718:) = ( 1700:from 1655:chain 1645:. If 1639:union 1637:is a 1629:) is 1619:chain 1386:group 1384:In a 897:) = ( 878:group 503:is a 475:group 409:group 377:group 373:group 160:from 156:is a 141:of a 43:is a 29:group 5762:and 5572:ISBN 5489:ISBN 5470:ISBN 5346:ISBN 5316:ISBN 5287:ISBN 5166:ISBN 5033:link 4779:ISBN 4666:and 4584:The 4562:xzyx 4558:xyzx 4540:: a 4519:: a 4491:: a 4448:: a 4380:and 4348:The 4102:and 3983:to: 3841:Let 3469:and 3020:acts 2968:and 2487:Let 2199:if 1854:) = 1846:and 1842:) = 1778:for 1745:) = 1693:, a 1689:and 1681:(or 1661:and 1453:and 1418:and 1317:and 1237:and 924:The 917:The 883:The 848:E(S) 634:The 602:and 433:and 417:) = 196:and 184:and 172:and 145:: a 76:and 5787:doi 5695:doi 5667:doi 5637:doi 5616:doi 5595:doi 5545:doi 5541:196 5512:doi 5508:192 5427:doi 5413:126 5396:doi 5392:116 5373:doi 5203:,b. 5015:doi 4669:gfg 4659:fgf 4526:is 4504:eSe 4502:if 4498:is 4478:axa 4471:in 4463:in 4455:is 4432:in 3438:in 3397:in 3389:in 3361:in 3261:in 3253:in 3198:in 3153:in 3125:in 3117:in 3066:in 3054:in 3022:on 2916:in 2884:of 2830:in 2777:in 2714:of 2573:on 2509:is 2469:in 2337:in 2329:in 2313:of 2176:on 2002:by 1868:of 1803:to 1788:If 1735:in 1704:to 1669:). 1641:of 1609:If 1532:On 1225:in 1164:in 945:bab 935:aba 705:is 666:is 515:of 469:(a 465:in 245:dom 215:dom 164:to 143:set 83:yxy 73:xyx 62:in 51:in 27:In 5807:: 5783:56 5781:. 5777:. 5734:32 5717:84 5691:65 5689:. 5663:28 5661:. 5655:. 5633:29 5631:. 5612:29 5610:. 5591:29 5589:. 5553:. 5539:. 5535:. 5518:. 5506:. 5425:. 5411:. 5369:22 5367:. 5363:. 5266:, 5208:^ 5029:}} 5025:{{ 5013:. 5001:96 4999:. 4691:. 4671:= 4661:= 4651:→ 4637:→ 4576:, 4572:, 4560:= 4480:= 3835:: 3821:, 3810:, 3442:, 3426:= 3424:gA 3296:gh 3292:hA 3285:, 3249:, 3239:gB 3237:≤ 3235:gA 3227:≤ 3222:, 3194:, 3182:= 3180:gA 3105:= 3097:gB 3095:= 3093:gA 3090:, 3062:, 2973:≤ 2912:, 2773:, 2541:= 2481:. 2461:≤ 2341:, 1872:. 1856:xa 1852:aφ 1844:Sa 1840:aφ 1782:: 1743:sθ 1720:st 1716:tθ 1714:)( 1712:sθ 1677:A 1529:. 1490:= 1448:≤ 1436:. 1425:xβ 1423:= 1421:xα 1405:≤ 1248:. 1235:aa 1085:e 1063:a 1041:c 1019:a 997:a 975:e 947:= 942:, 937:= 901:, 893:, 854:. 707:ss 523:). 484:: 477:. 451:xx 431:xx 429:, 415:ab 233:im 192:; 94:. 81:= 71:= 39:) 5793:. 5789:: 5766:. 5701:. 5697:: 5675:. 5669:: 5643:. 5639:: 5622:. 5618:: 5601:. 5597:: 5580:. 5561:. 5547:: 5526:. 5514:: 5497:. 5478:. 5456:. 5433:. 5429:: 5419:: 5402:. 5398:: 5381:. 5375:: 5354:. 5324:. 5295:. 5174:. 5035:) 5017:: 5007:: 4854:. 4829:. 4812:. 4787:. 4673:g 4663:f 4653:X 4649:Y 4645:g 4639:Y 4635:X 4631:f 4580:. 4578:z 4574:y 4570:x 4545:S 4524:S 4513:. 4511:e 4496:S 4485:. 4482:a 4473:S 4469:x 4465:S 4461:a 4453:S 4434:S 4422:S 4418:S 4386:β 4382:β 4378:α 4365:F 4333:. 4330:} 4325:+ 4321:) 4315:1 4308:X 4301:X 4298:( 4292:y 4289:, 4286:x 4281:| 4276:) 4271:1 4264:x 4260:x 4255:1 4248:y 4244:y 4241:, 4236:1 4229:y 4225:y 4220:1 4213:x 4209:x 4206:( 4202:, 4199:) 4196:x 4193:, 4190:x 4185:1 4178:x 4174:x 4171:( 4168:{ 4144:X 4112:X 4088:X 4064:Y 4052:F 4038:) 4033:Y 4028:, 4023:X 4018:, 4015:G 4012:( 4002:F 3998:P 3991:F 3977:E 3973:F 3969:σ 3961:F 3953:F 3942:E 3938:E 3924:) 3919:Y 3914:, 3909:X 3904:, 3901:G 3898:( 3895:P 3875:) 3870:Y 3865:, 3860:X 3855:, 3852:G 3849:( 3829:E 3825:) 3823:g 3819:A 3816:g 3812:g 3808:A 3806:( 3792:) 3787:Y 3782:, 3777:X 3772:, 3769:G 3766:( 3763:P 3751:. 3739:) 3736:h 3733:g 3730:, 3727:B 3724:g 3718:A 3715:( 3712:= 3709:) 3706:h 3703:, 3700:B 3697:( 3694:) 3691:g 3688:, 3685:A 3682:( 3656:} 3651:Y 3643:A 3638:1 3631:g 3627:: 3624:G 3616:Y 3608:) 3605:g 3602:, 3599:A 3596:( 3593:{ 3590:= 3587:) 3582:Y 3577:, 3572:X 3567:, 3564:G 3561:( 3558:P 3531:) 3526:Y 3521:, 3516:X 3511:, 3508:G 3505:( 3479:Y 3455:Y 3444:g 3440:G 3436:g 3431:; 3428:X 3407:Y 3395:A 3391:G 3387:g 3371:X 3359:X 3341:) 3336:Y 3331:, 3326:X 3321:, 3318:G 3315:( 3303:. 3300:A 3298:) 3290:( 3288:g 3271:X 3259:A 3255:G 3251:h 3247:g 3242:; 3229:B 3225:A 3208:X 3196:B 3192:A 3187:; 3184:B 3163:X 3151:A 3135:X 3123:B 3119:G 3115:g 3110:; 3107:B 3103:A 3076:X 3064:B 3060:A 3056:G 3052:g 3032:X 3012:G 3006:. 2992:Y 2980:B 2975:A 2971:B 2954:Y 2942:A 2926:X 2914:B 2910:A 2894:X 2866:Y 2840:Y 2828:B 2806:A 2787:Y 2775:B 2771:A 2751:Y 2724:X 2696:Y 2668:X 2656:E 2632:b 2627:1 2620:a 2616:, 2611:1 2604:b 2600:a 2594:b 2588:a 2575:S 2545:, 2543:σ 2517:σ 2511:E 2507:S 2500:σ 2496:E 2489:S 2479:E 2475:s 2471:S 2467:s 2463:s 2459:e 2455:E 2451:e 2447:S 2443:E 2426:. 2423:E 2417:s 2411:E 2405:e 2402:s 2376:. 2373:E 2367:s 2361:E 2355:s 2352:e 2339:S 2335:s 2331:E 2327:e 2321:- 2319:E 2311:E 2304:S 2300:E 2292:E 2275:. 2272:) 2269:S 2266:( 2263:E 2257:a 2251:e 2243:a 2240:, 2237:) 2234:S 2231:( 2228:E 2222:e 2219:, 2216:S 2210:a 2193:S 2189:ρ 2182:E 2178:S 2170:σ 2166:τ 2162:σ 2158:τ 2156:/ 2154:S 2150:S 2146:τ 2142:σ 2140:/ 2138:S 2134:S 2126:σ 2122:S 2118:S 2114:σ 2112:/ 2110:S 2102:σ 2085:. 2082:b 2079:, 2076:a 2070:c 2050:S 2044:c 2021:b 2013:a 2000:S 1963:. 1960:d 1957:b 1949:c 1946:a 1940:d 1932:c 1928:, 1925:b 1917:a 1900:ρ 1882:S 1878:S 1870:S 1850:( 1848:x 1820:S 1814:I 1801:S 1797:φ 1790:S 1750:θ 1747:s 1741:( 1737:S 1733:t 1731:, 1729:s 1724:θ 1722:) 1710:( 1706:T 1702:S 1698:θ 1691:T 1687:S 1667:S 1665:( 1663:E 1659:S 1651:S 1649:( 1647:E 1635:S 1627:S 1625:( 1623:E 1615:S 1613:( 1611:E 1604:S 1602:( 1600:E 1579:, 1576:f 1573:e 1570:= 1567:e 1561:f 1555:e 1538:S 1536:( 1534:E 1526:t 1510:R 1498:s 1492:t 1488:s 1483:t 1467:L 1455:s 1450:t 1446:s 1434:α 1430:x 1416:β 1412:α 1407:β 1403:α 1369:. 1364:1 1357:b 1348:1 1341:a 1334:b 1328:a 1302:d 1299:b 1293:c 1290:a 1284:d 1278:c 1275:, 1272:b 1266:a 1246:a 1243:a 1239:f 1231:e 1227:S 1223:f 1203:, 1200:f 1197:b 1194:= 1191:a 1185:b 1179:a 1166:S 1162:e 1142:, 1139:b 1136:e 1133:= 1130:a 1124:b 1118:a 1098:S 1082:d 1079:a 1076:a 1073:a 1069:e 1060:a 1057:e 1054:d 1051:a 1047:d 1038:b 1035:a 1032:a 1029:a 1025:c 1016:a 1013:c 1010:b 1007:a 1003:b 994:a 991:a 988:a 985:a 981:a 972:d 969:c 966:b 963:a 949:b 939:a 907:. 905:) 903:a 899:b 895:b 891:a 889:( 871:X 852:S 829:1 822:b 818:b 815:= 810:1 803:a 799:a 793:b 787:R 781:a 777:, 774:b 769:1 762:b 758:= 755:a 750:1 743:a 736:b 730:L 724:a 703:s 687:R 671:s 668:s 664:s 648:L 630:. 612:R 588:L 560:R 536:L 517:S 501:S 497:S 490:S 482:S 467:S 463:x 458:x 455:x 446:S 438:x 435:x 422:a 419:b 413:( 405:x 401:S 397:x 361:X 351:X 335:X 329:I 293:α 285:α 265:1 254:] 230:[ 227:= 198:β 194:α 190:X 186:β 182:α 178:X 174:B 170:A 166:B 162:A 154:X 150:α 111:x 109:( 107:f 103:f 99:x 79:y 69:x 64:S 60:y 53:S 49:x 41:S 20:)

Index

Inverse category
group
semigroup
regular semigroup
partial symmetries
Viktor Vladimirovich Wagner
Soviet Union
Gordon Preston
United Kingdom
partial bijections
set
partial transformation
function
domain
preimage
pseudogroups
composition of binary relations
empty set
associative
binary operation
symmetric inverse semigroup
converse relation
symmetric group
group
group
symmetric group
§ Homomorphisms and representations of inverse semigroups
group
monoid
idempotent

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