Trees, band monoids, and formal languages.
Turning retractions of an algebra into an algebra.
T-Varieties and Clones of T-terms
The aim of this paper is to describe how varieties of algebras of type τ can be classified by using the form of the terms which build the (defining) identities of the variety. There are several possibilities to do so. In [3], [19], [15] normal identities were considered, i.e. identities which have the form x ≈ x or s ≈ t, where s and t contain at least one operation symbol. This was generalized in [14] to k-normal identities and in [4] to P-compatible identities. More generally, we select a subset...
Two Congruence Lattices of Completely Simple Semigroups.
Two constructions of compatible relations
Two element direct limit classes of monounary algebras
Two enumeration principles for free algebras
Two types of retract irreducibility of connected monounary algebras
Let be a connected monounary algebra. The paper deals with retract irreducibility of in the class of all connected monounary algebras and in the class of all monounary algebras.
Two-generated idempotent groupoids with small clones
A characterization of all classes of idempotent groupoids having no more than two essentially binary term operations with respect to small finite models is given.