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Semigroups with zero whose idempotents form a subsemigroup

  • Gracinda M. S. Gomes (a1) and John M. Howie (a2)


The structure of a categorical, E*-dense, E*-unitary E-semigroup S is elucidated in terms of a ‘B-quiver’, where B is a primitive inverse semigroup. In the case where S is strongly categorical, B is a Brandt semigroup. A covering theorem is also proved, to the effect that every categorical E*-dense E-semigroup has a cover which is a categorical, E*-dense, E*-unitary E-semigroup.



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Semigroups with zero whose idempotents form a subsemigroup

  • Gracinda M. S. Gomes (a1) and John M. Howie (a2)


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