共查询到20条相似文献,搜索用时 15 毫秒
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In this paper we investigate under which conditions a monoid R is defined by the endomorphism monoid of an act over R. More
precisely, we ask when an isomorphism between two such endomorphism monoids over monoids R1 and R2 is induced by a semilinear isomorphism. The question is considered also for ordered and for topological monoids. On the way
we characterize monoids over which all projective acts are free. An abstract of this paper appeared in the Proceedings of
the Conference on Semigroups, Szeged 1972. 相似文献
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A graph semigroup refers to a monoid whose defining relations are of the form xixj=xjxi. We describe the centralizer of an arbitrary element of a graph semigroup, show that there exists a unique factorization
of any element into commuting parts, and prove related results.
Dedicated to L. M. Gluskin on the occasion of his sixtieth birthday 相似文献
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Alfred Geroldinger Franz Halter-Koch Wolfgang Hassler Florian Kainrath 《Semigroup Forum》2008,67(1):1-21
Abstract. No abstract. 相似文献
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We relate the old and new cohomology monoids of an arbitrary monoid M with coefficients in semimodules over M, introduced in the author’s previous papers, to monoid and group extensions. More precisely, the old and new second cohomology monoids describe Schreier extensions of semimodules by monoids, and the new third cohomology monoid is related to a certain group extension problem. 相似文献
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It is proved that in the variety of positive Sugihara monoids, every finite subdirectly irreducible algebra is a retract of
a free algebra. It follows that every quasivariety of positive Sugihara monoids is a variety, in contrast with the situation
in several neighboring varieties. This result shows that when the logic R-mingle is formulated with the Ackermann constant t, then its full negation-free fragment is hereditarily structurally complete.
Presented by R. W. Quackenbush.
Received August 28, 2005; accepted in final form July 31, 2006. 相似文献
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In this paper, we define and study what we call the double Catalan monoid. This monoid is the image of a natural map from the 0-Hecke monoid to the monoid of binary relations. We show that the double Catalan monoid provides an algebraization of the (combinatorial) set of 4321-avoiding permutations and relate its combinatorics to various off-shoots of both the combinatorics of Catalan numbers and the combinatorics of permutations. In particular, we give an algebraic interpretation of the first derivative of the Kreweras involution on Dyck paths, of 4321-avoiding involutions and of recent results of Barnabei et al. on admissible pairs of Dyck paths. We compute a presentation and determine the minimal dimension of an effective representation for the double Catalan monoid. We also determine the minimal dimension of an effective representation for the 0-Hecke monoid. 相似文献
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D. G. FitzGerald 《Semigroup Forum》2010,80(3):484-509
Factorizable inverse monoids constitute the algebraic theory of those partial symmetries which are restrictions of automorphisms; the formal definition is that each element is the product of an idempotent and an invertible. This class of monoids has theoretical significance, and includes concrete instances which are important in various contexts. This survey is organised around the idea of group acts on semilattices and contains a large range of examples. Topics also include methods for construction of factorizable inverse monoids, and aspects of their inner structure, morphisms, and presentations. 相似文献
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Perfect monoids revisited 总被引:1,自引:0,他引:1
Mati Kilp 《Semigroup Forum》1996,53(1):225-229
A new characterization of perfect monoids, i.e., monoids over which every act has a projective cover, is given. As was shown
by Fountain [1] a monoid is perfect if and only if all strongly flat acts over it are projective. Using our new condition,
an alternative version is given of a recent result, of Liu [7] describing monoids over which all strongly flat right acts
are projective generators, or are free.
This research has been supported by the Estonian Science Foundation, Grant No. 930.
I would like to thank the School of Mathematical and Computational Sciences of the University of St. Andrews for excellent
working conditions. 相似文献
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Completely quasi-projective monoids 总被引:3,自引:0,他引:3
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We show that no finite set of first-order axioms can define the class of representable semilattice-ordered monoids.
Received July 2, 2004; accepted in final form February 22, 2007. 相似文献
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