On the number of finite algebraic structures
We prove that every clone of operations on a finite set $A$, if it contains a Malcev operation, is finitely related – i.e., identical with the clone of all operations respecting $R$ for some finitary relation $R$ over $A$. It follows that for a fixed finite set $A$, the set of all such Malcev clones...
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Veröffentlicht in: | Journal of the European Mathematical Society : JEMS 2014-01, Vol.16 (8), p.1673-1686 |
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Sprache: | eng |
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Zusammenfassung: | We prove that every clone of operations on a finite set $A$, if it contains a Malcev operation, is finitely related – i.e., identical with the clone of all operations respecting $R$ for some finitary relation $R$ over $A$. It follows that for a fixed finite set $A$, the set of all such Malcev clones is countable. This completes the solution of a problem that was first formulated in 1980, or earlier: how many Malcev clones can finite sets support? More generally, we prove that every finite algebra with few subpowers has a finitely related clone of term operations. Hence modulo term equivalence and a renaming of the elements, there are only countably many finite algebras with few subpowers, and thus only countably many finite algebras with a Malcev term. |
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ISSN: | 1435-9855 1435-9863 |
DOI: | 10.4171/JEMS/472 |