A deceptive fact about functions
The paper provides a proof of a combinatorial result which pertains to the characterization of the set of equations which are solvable in the composition monoid of all partial functions on an infinite set.
A deductive calculus for conditional equational systems with built-in predicates as premises.
A dichotomy theorem for mono-unary algebras
We study the isomorphism relation of invariant Borel classes of countable mono-unary algebras and prove a strong dichotomy theorem.
A duality between unary algebras and their subuniverse lattices
A dyadic view of rational convex sets
Let be a subfield of the field of real numbers. Equipped with the binary arithmetic mean operation, each convex subset of becomes a commutative binary mode, also called idempotent commutative medial (or entropic) groupoid. Let and be convex subsets of . Assume that they are of the same dimension and at least one of them is bounded, or is the field of all rational numbers. We prove that the corresponding idempotent commutative medial groupoids are isomorphic iff the affine space ...
A factorization of quasiorder hypergroups
The contribution is devoted to the question of the interchange of the construction of a quasiorder hypergroup from a quasiordered set and the factorization.
A first-order logic for multi-algebras.
A functional characterization of parallelogram spaces
A Galois correspondence for universal algebras
A generalization of a theorem of Skala
A generalization of equivalence relations.
A generalization of Płonka sums
A generalization of the direct product of universal algebras
A groupoid characterization of Boolean algebras
We present a groupoid which can be converted into a Boolean algebra with respect to term operations. Also conversely, every Boolean algebra can be reached in this way.
A lattice of homomorphs
A matrix characterization of the maximal groups in
A new Proof of Prešić's Theorem on Finite Equations
A New Proof of the Eilenberg-Zilber-Cartier Theorem.
A note on algebraic categories
A note on categories of partial algebras