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    Pointlike sets for varieties determined by groups

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    For a variety of finite groups H\mathbf H, let H‾\overline{\mathbf H} denote the variety of finite semigroups all of whose subgroups lie in H\mathbf H. We give a characterization of the subsets of a finite semigroup that are pointlike with respect to H‾\overline{\mathbf H}. Our characterization is effective whenever H\mathbf H has a decidable membership problem. In particular, the separation problem for H‾\overline{\mathbf H}-languages is decidable for any decidable variety of finite groups H\mathbf H. This generalizes Henckell's theorem on decidability of aperiodic pointlikes
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