共查询到20条相似文献,搜索用时 62 毫秒
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Valdis Laan 《Periodica Mathematica Hungarica》2010,60(1):81-94
Two semigroups are called strongly Morita equivalent if they are contained in a Morita context with unitary bi-acts and surjective
mappings. We consider the notion of context equivalence which is obtained from the notion of strong Morita equivalence by
dropping the requirement of unitariness. We show that context equivalence is an equivalence relation on the class of factorisable
semigroups and describe factorisable semigroups that are context equivalent to monoids or groups, and semigroups with weak
local units that are context equivalent to inverse semigroups, orthodox semigroups or semilattices. 相似文献
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半群上Rees矩阵半群的半格的结构 总被引:1,自引:0,他引:1
曹永林 《纯粹数学与应用数学》1998,(2)
推广了M.Petrich在文[1]中所用的方法,得到了幺半群上Rees矩阵半群的半格的一个结构定理.研究了单幂幺半群上Rees矩阵半群的半格的性质并给出了矩形单幂幺半群的半格的若干等价刻划. 相似文献
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A. V. Mikhalev E. V. Ovchinnikova A. A. Palyutin A. A. Stepanova 《Journal of Mathematical Sciences》2007,140(2):250-285
This work is devoted to results obtained in the model theory of regular polygons. We give a characterization of monoids with
axiomatizable and model-complete class of regular polygons. We describe monoids with complete class of regular polygons that
satisfy some additional conditions. We study monoids whose regular core is represented as a union of finitely many principal
right ideals and all regular polygons over which have a stable and superstable theory. We prove the stability of the class
of all regular polygons over a monoid provided this class is axiomatizable and model-complete. We also describe monoids for
which the class of all regular polygons is superstable and ω-stable provided this class is axiomatizable and model-complete.
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Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 10, No. 4, pp. 107–157, 2004. 相似文献
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The structure of superabundant semigroups 总被引:9,自引:0,他引:9
K.P.Shum 《中国科学A辑(英文版)》2004,47(5):756-771
A structure theorem for superabundant semigroups in terms of semilattices of normalized Rees matrix semigroups over some cancellative monoids is obtained. This result not only provides a construction method for superabundant semigroups but also generalizes the well-known result of Petrich on completely regular semigroups. Some results obtained by Fountain on abundant semigroups are also extended and strengthened. 相似文献
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Paul Blanchard 《Semigroup Forum》1991,43(1):218-246
We study some syntactic properties of languages obtained from rational languages through counting operations. These counting operations use the congruences-threshold p, modulo n—on the set of integers. We show that in some cases they preserve the properties of syntactic monoids: the structure of idempotent and commutative monoids is not modified, aperiodic monoids with central idempotents keep their central idempotents and their regular D-classes still are groups although not trivial, aperiodic left (right) nilsimple semigroups still have regular R (L)-classes which are (non trivial) groups. If possible results are expressed in terms of varieties of semigroups or monoids. 相似文献
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The paper is devoted to the investigation of uniform acts over semigroups perceived as an overclass of subdirectly irreducible acts. We establish conditions for a uniform act to be subdirectly irreducible. In particular, we prove that uniform acts with two zeros are subdirectly irreducible. Ultimately we investigate monoids which are uniform as right acts over themselves and we describe regular monoids with this property. 相似文献
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Presentations are found for the wreath product of two monoids, the Schützenberger product of two monoids, the Bruck-Reilly extension of a monoid, strong semilattices of monoids and Rees matrix semigroups of monoids. 相似文献
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In this paper,we investigate a class of factorisable IC quasi-adequate semigroups,so-called,factorisable IC quasi-adequate semigroups of type-(H,I).Some characterizations of factorisable IC quasi-adequate semigroups of type-(H,I) are obtained.In particular,we prove that any IC quasi-adequate semigroup has a factorisable IC quasi-adequate subsemigroups of type-(H,I) and a band of cancellative monoids. 相似文献
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A. A. Stepanova 《Algebra and Logic》2002,41(4):267-273
We deal with monoids possessing a stable class of torsion-free polygons over them. 相似文献
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《代数通讯》2013,41(11):4465-4484
Abstract We generalise theory of Lawson for inverse monoids with zero to wider classes of regular semigroups. We give a structure theorem for ?-unipotent monoids with zero. Several connections between cancellative categories and 0-E-unitary semigroups are obtained as an application of the results of this paper. 相似文献
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Two-sided restriction semigroups and their handed versions arise from a number of sources. Attracting a deal of recent interest, they appear under a plethora of names in the literature. The class of left restriction semigroups essentially provides an axiomatisation of semigroups of partial mappings. It is known that this class admits proper covers, and that proper left restriction semigroups can be described by monoids acting on the left of semilattices. Any proper left restriction semigroup embeds into a semidirect product of a semilattice by a monoid, and moreover, this result is known in the wider context of left restriction categories. The dual results hold for right restriction semigroups.What can we say about two-sided restriction semigroups, hereafter referred to simply as restriction semigroups? Certainly, proper covers are known to exist. Here we consider whether proper restriction semigroups can be described in a natural way by monoids acting on both sides of a semilattice.It transpires that to obtain the full class of proper restriction semigroups, we must use partial actions of monoids, thus recovering results of Petrich and Reilly and of Lawson for inverse semigroups and ample semigroups, respectively. We also describe the class of proper restriction semigroups such that the partial actions can be mutually extendable to actions. Proper inverse and free restriction semigroups (which are proper) have this form, but we give examples of proper restriction semigroups which do not. 相似文献
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Peter R. Jones 《Semigroup Forum》2013,86(2):337-361
The left restriction semigroups have arisen in a number of contexts, one being as the abstract characterization of semigroups of partial maps, another as the ‘weakly left E-ample’ semigroups of the ‘York school’, and, more recently as a variety of unary semigroups defined by a set of simple identities. We initiate a study of the lattice of varieties of such semigroups and, in parallel, of their two-sided versions, the restriction semigroups. Although at the very bottom of the respective lattices the behaviour is akin to that of varieties of inverse semigroups, more interesting features are soon found in the minimal varieties that do not consist of semilattices of monoids, associated with certain ‘forbidden’ semigroups. There are two such in the one-sided case, three in the two-sided case. Also of interest in the one-sided case are the varieties consisting of unions of monoids, far indeed from any analogue for inverse semigroups. In a sequel, the author will show, in the two-sided case, that some rather surprising behavior is observed at the next ‘level’ of the lattice of varieties. 相似文献
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N. Levan 《Journal of Optimization Theory and Applications》1993,76(1):111-130
This paper studies the strong stabilizability of two classes of Hilbert space contraction semigroups: (i) strict contraction semigroups, which include those with strictly dissipative generators; and (ii) isometric or unitary semigroups. The former class is already weakly stable, while the latter is not strongly stable over the whole space. Our tool is the functional model of Hilbert space contractions; hence, strong stability of the semigroup is studied via stability of its cogenerator. It is shown that a strict contraction semigroup is, in general, not strongly stabilized by the feedback –B*, while an isometric or a unitary semigroup is strongly stabilized by the same feedback, providedB is not compact. 相似文献
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Mohan S. Putcha 《Semigroup Forum》2011,83(1):65-74
We define abstract canonical semigroups modeled after the canonical reductive monoids associated with the canonical compactification
of a group of adjoint type. It then becomes possible for us to come up with semigroups having some of the algebraic properties
of monoids of Lie type (without first starting with a group). 相似文献
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Catarina A. Carvalho 《Semigroup Forum》2009,79(1):145-158
We say that a class of monoids satisfies the property ℘ if every monoid in that class that admits a finitely presented Bruck–Reilly
extension is finitely generated. We show that completely (0-)simple semigroups satisfy ℘, and that the direct product of two
monoids in a class that satisfy ℘ also satisfies ℘ subject to a certain condition on the endomorphisms of the direct product.
As a consequence of this result we obtain a new class of bands and a new class of completely regular semigroups that satisfy
property ℘. 相似文献