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    Saturated and epimorphically closed varieties of semigroups
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    Abstract:
    Abstract We establish a necessary condition ( E ) for a semigroup variety to be closed under the taking of epimorphisms and a necessary condition ( S ) for a variety to consist entirely of saturated semigroups. Condition ( S ) is shown to be sufficient for heterotypical varieties and a stronger condition ( S ′) is shown to be sufficient for homotypical varieties.
    The aim of the present paper is to give some general surjectivity theorems for multifunctions using tangent cones and generalized differentiability assumptions.
    Tangent cone
    Citations (7)
    In this paper we consider a generalization to analytic multifunctions of the classical Hardy space theory of analytic functions on the unit disc. With \K(lambda) = sup (\z\; z is an element of K(lambda)) we define the Nevanlinna class N and the classes H