Seminearrings, seminearfields and their semigroup-theoretical background.
Recently, we have shown that a semiring is completely regular if and only if is a union of skew-rings. In this paper we show that a semiring satisfying can be embedded in a completely regular semiring if and only if is additive separative.
The semisymmetrization of an arbitrary quasigroup builds a semisymmetric quasigroup structure on the cube of the underlying set of the quasigroup. It serves to reduce homotopies to homomorphisms. An alternative semisymmetrization on the square of the underlying set was recently introduced by A. Krapež and Z. Petrić. Their construction in fact yields a Mendelsohn quasigroup, which is idempotent as well as semisymmetric. We describe it as the Mendelsohnization of the original quasigroup. For quasigroups...