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Dualities and algebras with a near-unanimity term

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Abstract

Let P be a finite relational structure that admits a (k +  1)-ary nearunanimity polymorphism. Then the NU Duality Theorem tells us that the algebra , whose operations are the polymorphisms of P, is dualisable with a dualising alter ego given by. We show that a more efficient alter ego can be obtained by using obstructions, as introduced by Zádori. We show that in the case that P is an ordered set (and therefore is an order-primal algebra), the duality that we obtain is strong. We close the paper by showing that if P is a finite fence, then our duality is optimal.

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Authors and Affiliations

  1. Department of Mathematics, Faculty of Science, Silpakorn University, Sanam Chan Palace Campus, Nakorn Pathom, 73000, Thailand

    Ratana Srithus & Udom Chotwattakawanit

Authors
  1. Ratana Srithus
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  2. Udom Chotwattakawanit
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Correspondence to Ratana Srithus.

Additional information

Presented by M. Haviar.

The research of the first author was supported by the Thailand Research Fund under grant no. MRG5680113.

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Srithus, R., Chotwattakawanit, U. Dualities and algebras with a near-unanimity term. Algebra Univers. 76, 111–126 (2016). https://doi.org/10.1007/s00012-016-0388-x

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