Results 51 to 60 of about 543 (107)

Kernels of orthodox semigroup homomorphisms [PDF]

open access: yesJournal of the Australian Mathematical Society, 1976
Any congruence on an orthodox semigroup S induces a partition of the set E of idempotents of S satisfying certain normality conditions. Meakin (1970) has characterized those partitions of E which are induced by congruences on S as well as the largest congruence ρ and the smallest congruence σ on S corresponding to such a partition of E. In this paper a
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Identities of orthodox semigroup rings

open access: yesSemigroup Forum, 1994
Let \(R\) be a ring with identity, let \(S\) be a semigroup, and let \(T\) be the subsemigroup of \(S\) generated by all idempotents of \(S\). The semigroup ring of \(S\) over \(R\) is denoted by \(R[S]\). The author is interested in the two following problems. Problem 1: when is \(R[S]\) a ring with identity? Problem 2: suppose that \(R[S]\) is a ring
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Orthodox ternary semigroups

open access: yes, 2011
Using the notion of idempotent pairs we dene orthodox ternary semigroups and generalize various properties of binary orthodox semigroups to the case of ternary semigroups. Also right strongly regular ternary semigroups are characterized.
Sheeja, G., SriBala, S.
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Orthodox congruences on regular semigroups

open access: yesSemigroup Forum, 1988
We show that every orthodox congruence on a regular semigroup S is completely described by an orthodox congruence pair for S. A pair \((\xi,K)\) consisting of a normal congruence \(\xi\) on \(\) such that \(/\xi\) is a band and a normal subsemigroup K of S is said to be an orthodox congruence pair for S if, for all \(a,b\in S\), \(a'\in V(a)\), \(x\in \
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Semilattices of bisimple orthodox semigroups

open access: yesSemigroup Forum, 1974
A structure theorem for bisimple orthodox semigroups was given by Clifford [2]. In this paper we determine all homomorphisms of a certain type from one bisimple orthodox semigroup into another, and apply the results to give a structure theorem for any semilattice of bisimple orthodox semigroups with identity in which the set of identity elements forms ...
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Certain subsemigroups of orthodox semigroups

open access: yesSemigroup Forum, 1985
Let S be an orthodox semigroup and E(S) the band of idempotents of S. The author describes (1) the least fundamental inverse congruence on S, (2) the greatest subsemigroup of S containing E(S) which is a union (band) of groups, and (3) a necessary and sufficient condition for the union of maximal subgroups of S to be a subsemigroup of S.
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Matrix congruences on orthodox semigroups

open access: yesSemigroup Forum, 1985
A matrix congruence \(\sigma\) on a semigroup S is a congruence for which S/\(\sigma\) is a rectangular band. In this paper, the author presents conditions by which a matrix congruence on the band \(E_ S\) of idempotents of an orthodox semigroup S can be extended to a matrix congruence on S.
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