Finite Proper Covers in a Class of Finite Semigroups with Commuting Idempotents |
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Authors: | Gomes and Gould |
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Institution: | (1) Centro de álgebra da Universidade de Lisboa Avenida Prof Gama Pinto 2 1649-003 Lisboa, Portugal and Departamento de Mathématica Faculdade de Ciências Universidade de Lisboa 1746—016 Lisboa, Portugal ggomes@cii.fc.ul.pt, PT;(2) Department of Mathematics University of York Heslington York YO10 5DD, UK varg1@york.ac.uk, GB |
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Abstract: |
Abstract. Weakly left ample semigroups are a class of semigroups that are (2,1) -subalgebras of semigroups of partial transformations, where the unary operation takes a transformation α to the identity map in the domain of α . It is known that there is a class of proper weakly left ample semigroups whose structure is determined by unipotent monoids acting on semilattices or categories. In
this paper we show that for every finite weakly left ample semigroup S , there is a finite proper weakly left ample semigroup and an onto morphism from to S which separates idempotents. In fact, is actually a (2,1) -subalgebra of a symmetric inverse semigroup, that is, it is a left ample semigroup (formerly, left type A). |
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Keywords: | |
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