Factorable congruences and factorable congruence blocks on powers of a finite algebra
Factorable congruences and strict refinement.
Factorization and non-algebraic categories
Factor-union representation of phenotype systems.
Families of independent sets in finite unary algebras
Families of strongly projective graphs
We give several characterisations of strongly projective graphs which generalise in many respects odd cycles and complete graphs [7]. We prove that all known families of projective graphs contain only strongly projective graphs, including complete graphs, odd cycles, Kneser graphs and non-bipartite distance-transitive graphs of diameter d ≥ 3.
Fast algorithms for finding a subdirect decomposition and interesting congruences of finite algebras
Feebly canonical and 1-hypergroups
Filters and annihilators in implication algebras
Filters and Simple Graphic Algebras.
Finite atomistic lattices that can be represented as lattices of quasivarieties
We prove that a finite atomistic lattice can be represented as a lattice of quasivarieties if and only if it is isomorphic to the lattice of all subsemilattices of a finite semilattice. This settles a conjecture that appeared in the context of [11].
Finite basis problem for 2-testable monoids
A monoid S 1 obtained by adjoining a unit element to a 2-testable semigroup S is said to be 2-testable. It is shown that a 2-testable monoid S 1 is either inherently non-finitely based or hereditarily finitely based, depending on whether or not the variety generated by the semigroup S contains the Brandt semigroup of order five. Consequently, it is decidable in quadratic time if a finite 2-testable monoid is finitely based.
Finite basis theorem for systems of semigroup identities.
Finite hull systems and their implication bases. (Endliche Hüllensysteme und ihre Implikationenbasen.)
Finite monogenic distributive systems
Finite Symmetric Functions with Non-Trivial Arity Gap
Given an n-ary k-valued function f, gap(f) denotes the essential arity gap of f which is the minimal number of essential variables in f which become fictive when identifying any two distinct essential variables in f. In the present paper we study the properties of the symmetric function with non-trivial arity gap (2 ≤ gap(f)). We prove several results concerning decomposition of the symmetric functions with non-trivial arity gap with its minors or subfunctions. We show that all non-empty sets of...
Finitely axiomatizable varieties of BCK-algebras.
Finitely generated almost universal varieties of -lattices
A concrete category is (algebraically) universal if any category of algebras has a full embedding into , and is almost universal if there is a class of -objects such that all non-constant homomorphisms between them form a universal category. The main result of this paper fully characterizes the finitely generated varieties of -lattices which are almost universal.
Finitely generated almost universal varieties of 0-lattices.
Finitely generated commutative division semirings