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Canonical Varieties of Completely Regular Semigroups

Part of: Semigroups

Published online by Cambridge University Press:  09 April 2009

Mario Petrich
21420 Bol, Brač Croatia
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Completely regular semigroups CR are regarded here as algebras with multiplication and the unary operation of inversion. Their lattice of varieties is denoted by L(CR). Let B denote the variety of bands and L(B) the lattice of its subvarieties. The mapping VVB is a complete homomorphism of L(CR) onto L(B). The congruence induced by it has classes that are intervals, say VB = [VB, VB] for VL(CR). Here VB = VB. We characterize VB in several ways, the principal one being an inductive way of constructing bases for v-irreducible band varieties. We term the latter canonical. We perform a similar analysis for the intersection of these varieties with the varieties BG, OBG and B.

Research Article
Copyright © Australian Mathematical Society 2007


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