Laws for generalised interior operations in semigroups (Q6098992)

Motivated by interior operators and by analogous generalisations of closure operators to semigroups in general, the author defines left, right and two-sided interior operations on a semigroup \(S\) in terms of a distinguished set of idempotents \(E\) using the natural order. The author generalises them using suitable Green-like relations and characterises the resulting classes of unary and biunary semigroups as quasivarieties or varieties.