33 research outputs found

    The number of clones determined by disjunctions of unary relations

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    We consider finitary relations (also known as crosses) that are definable via finite disjunctions of unary relations, i.e. subsets, taken from a fixed finite parameter set Γ\Gamma. We prove that whenever Γ\Gamma contains at least one non-empty relation distinct from the full carrier set, there is a countably infinite number of polymorphism clones determined by relations that are disjunctively definable from Γ\Gamma. Finally, we extend our result to finitely related polymorphism clones and countably infinite sets Γ\Gamma.Comment: manuscript to be published in Theory of Computing System
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