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Free trees and the optimal bound in Wehrung's theorem

Pavel Růžička (2008)

Fundamenta Mathematicae

We prove that there is a distributive (∨,0,1)-semilattice of size ℵ₂ such that there is no weakly distributive (∨,0)-homomorphism from C o n c A to with 1 in its range, for any algebra A with either a congruence-compatible structure of a (∨,1)-semi-lattice or a congruence-compatible structure of a lattice. In particular, is not isomorphic to the (∨,0)-semilattice of compact congruences of any lattice. This improves Wehrung’s solution of Dilworth’s Congruence Lattice Problem, by giving the best cardinality...

Fuzzy sets (in)equations with a complete codomain lattice

Vanja Stepanović, Andreja Tepavčević (2022)

Kybernetika

The paper applies some properties of the monotonous operators on the complete lattices to problems of the existence and the construction of the solutions to some fuzzy relational equations, inequations, and their systems, taking a complete lattice for the codomain lattice. The existing solutions are extremal - the least or the greatest, thus we prove some extremal problems related to fuzzy sets (in)equations. Also, some properties of upper-continuous lattices are proved and applied to systems of...

Generalized cardinal properties of lattices and lattice ordered groups

Ján Jakubík (2004)

Czechoslovak Mathematical Journal

We denote by K the class of all cardinals; put K ' = K { } . Let 𝒞 be a class of algebraic systems. A generalized cardinal property f on 𝒞 is defined to be a rule which assings to each A 𝒞 an element f A of K ' such that, whenever A 1 , A 2 𝒞 and A 1 A 2 , then f A 1 = f A 2 . In this paper we are interested mainly in the cases when (i) 𝒞 is the class of all bounded lattices B having more than one element, or (ii) 𝒞 is a class of lattice ordered groups.

Generating methods for principal topologies on bounded lattices

Funda Karaçal, Ümit Ertuğrul, M. Nesibe Kesicioğlu (2021)

Kybernetika

In this paper, some generating methods for principal topology are introduced by means of some logical operators such as uninorms and triangular norms and their properties are investigated. Defining a pre-order obtained from the closure operator, the properties of the pre-order are studied.

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