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Nilpotents and congruences on semigroups of transformations with fixed rank

Published online by Cambridge University Press:  14 November 2011

M. Paula O. Marques-Smith
Affiliation:
Departamento de Matematica, Universidade do Minho, 4700 Braga, Portugal
R. P. Sullivan
Affiliation:
Department of Mathematics, University of Western Australia, Nedlands, WA 6009, Australia

Abstract

In 1988, Howie and Marques-Smith studied Pm, a Rees quotient semigroup of transformations associated with a regular cardinal m, and described the elements which can be written as a product of nilpotents in Pm. In 1981, Marques proved that if Δm denotes the Malcev congruence on Pm, then Pmm is congruence-free for any infinite m. In this paper, we describe the products of nilpotents in Pm when m is nonregular, and determine all the congruences on Pm when m is an arbitrary infinite cardinal. We also investigate when a nilpotent is a product of idempotents.

Type
Research Article
Copyright
Copyright © Royal Society of Edinburgh 1995

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