It is well known that every subvariety of the variety of semigroups need not be absolutely
closed. Thus, identifying those subvarieties that are closed in themselves or in larger …

The complete characterization of saturated varieties of semigroups remains an unsolved
problem. The primary objective of this paper is to make significant progress in this direction …

We show that all subvarieties of the variety of rectangular bands are closed in the variety of $
n $-nilpotent extension of bands. Ahanger, Nabi and Shah in [1] have proved that the variety …

We show that for each n≥ 2∈ N, the varieties V n=[x 1 x 2 x 3= x 1 nxi 1 xi 2 xi 3] where i is
any non-trivial permutation of {1, 2, 3} are closed. Further, we show that for each n∈ N, the …

As the varieties of rectangular bands and right [left] normal bands are not absolutely closed,
so it is worth to find subvarieties of the variety of all semigroups that are closed in itself or …

In a concrete category, a surjective morphism is always an epimorphism but the converse is
not always true in the category of semigroups. However, the converse holds for saturated …