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Submaximal clones over a three-element set up to minor-equivalence

  • Albert Vucaj,
  • Dmitriy Zhuk

摘要

We study clones modulo minor homomorphisms, which are mappings from one clone to another preserving arities of operations and respecting permutation and identification of variables. Minor-equivalent clones satisfy the same sets of identities of the form \(f(x_1,\dots ,x_n)\approx g(y_1,\dots ,y_m)\) f ( x 1 , , x n ) g ( y 1 , , y m ) , also known as minor identities, and therefore share many algebraic properties. Moreover, it was proved that the complexity of the \({\text {CSP}}\) CSP of a finite structure \(\mathbb {A}\) A only depends on the set of minor identities satisfied by the polymorphism clone of \(\mathbb {A}\) A . In this article we consider the poset that arises by considering all clones over a three-element set with the following order: we write \(\mathcal {C}\ {\preceq _{\textrm{m}}}\ \mathcal {D}\) C m D if there exists a minor homomorphism from \(\mathcal {C}\) C to \(\mathcal {D}\) D . We show that the aforementioned poset has only three submaximal elements.