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Polyhedral convex cones and the equational theory of the bicyclic semigroup

Part of: Semigroups

Published online by Cambridge University Press:  09 April 2009

F. Pastijn
Affiliation:
Department of Mathematics, Statistics and Computer Science, Marquette University, Milwaukee WI 53201-1881, USA, e-mail: [email protected]
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Abstract

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To any given balanced semigroup identity UW a number of polyhedral convex cones are associated. In this setting an algorithm is proposed which determines whether the given identity is satisfied in the bicylic semigroup or in the semigroup . The semigroups BC and E deserve our attention because a semigroup variety contains a simple semigroup which is not completely simple (respectively, which is idempotent free) if and only if this variety contains BC (respectively, E). Therefore, for a given identity UW it is decidable whether or not the variety determined by UW contains a simple semigroup which is not completely simple (respectively, which is idempotent free).

Type
Research Article
Copyright
Copyright © Australian Mathematical Society 2006

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