On central relations of complete lattices
On certain congruence lattices of finite unary algebras
On certain functions defined in universal algebras. (Sur certaines fonctions définies dans des algèbres universelles.)
On classes of algebraic systems closed with respect to quotients
On classes of algebras definable by regular equations
On clones determined by their initial segments
On clones of relations
On closed classes of quasilinear functions
On compatible and order-preserving functions on lattices
On completions of partial monounary algebras
On congruence lattices in a category
On congruence lattices of finite partial unary algebras
On congruence lattices of regular semigroups with Q-inverse transversals.
On congruence relations of monounary algebras. I
On congruence relations of monounary algebras. II
On congruences in direct sums of algebras
On congruences of -sets
We describe -sets whose congruences satisfy some natural lattice or multiplicative restrictions. In particular, we determine -sets with distributive, arguesian, modular, upper or lower semimodular congruence lattice as well as congruence -permutable -sets for .
On congruences of ...x-normal semigroups.
On connected unars with regular endomorphism monoids
On connections between hypergraphs and algebras
The aim of the present paper is to translate some algebraic concepts to hypergraphs. Thus we obtain a new language, very useful in the investigation of subalgebra lattices of partial, and also total, algebras. In this paper we solve three such problems on subalgebra lattices, other will be solved in [[Pio4]]. First, we show that for two arbitrary partial algebras, if their directed hypergraphs are isomorphic, then their weak, relative and strong subalgebra lattices are isomorphic. Secondly, we prove...