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Computing the greatest 𝐗 -eigenvector of a matrix in max-min algebra

Ján Plavka (2016)

Kybernetika

A vector x is said to be an eigenvector of a square max-min matrix A if A ⊗ x = x . An eigenvector x of A is called the greatest 𝐗 -eigenvector of A if x ∈ 𝐗 = { x ; x ̲ ≤ x ≤ x ¯ } and y ≤ x for each eigenvector y ∈ 𝐗 . A max-min matrix A is called strongly 𝐗 -robust if the orbit x , A ⊗ x , A 2 ⊗ x , ⋯ reaches the greatest 𝐗 -eigenvector with any starting vector of 𝐗 . We suggest an O ( n 3 ) algorithm for computing the greatest 𝐗 -eigenvector of A and study the strong 𝐗 -robustness. The necessary and sufficient conditions for strong 𝐗 -robustness are introduced and an efficient...

Congruence classes in Brouwerian semilattices

Ivan Chajda, Helmut Länger (2001)

Discussiones Mathematicae - General Algebra and Applications

Brouwerian semilattices are meet-semilattices with 1 in which every element a has a relative pseudocomplement with respect to every element b, i. e. a greatest element c with a∧c ≤ b. Properties of classes of reflexive and compatible binary relations, especially of congruences of such algebras are described and an abstract characterization of congruence classes via ideals is obtained.

Congruence lattices in varieties with compact intersection property

Filip Krajník, Miroslav Ploščica (2014)

Czechoslovak Mathematical Journal

We say that a variety 𝒱 of algebras has the Compact Intersection Property (CIP), if the family of compact congruences of every A ∈ 𝒱 is closed under intersection. We investigate the congruence lattices of algebras in locally finite, congruence-distributive CIP varieties and obtain a complete characterization for several types of such varieties. It turns out that our description only depends on subdirectly irreducible algebras in 𝒱 and embeddings between them. We believe that the strategy used here can...

Congruence lattices of intransitive G-Sets and flat M-Sets

Steve Seif (2013)

Commentationes Mathematicae Universitatis Carolinae

An M-Set is a unary algebra 〈 X , M 〉 whose set M of operations is a monoid of transformations of X ; 〈 X , M 〉 is a G-Set if M is a group. A lattice L is said to be represented by an M-Set 〈 X , M 〉 if the congruence lattice of 〈 X , M 〉 is isomorphic to L . Given an algebraic lattice L , an invariant Π ( L ) is introduced here. Π ( L ) provides substantial information about properties common to all representations of L by intransitive G-Sets. Π ( L ) is a sublattice of L (possibly isomorphic to the trivial lattice), a Π -product lattice. A Π -product...

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