On Special Amalgams and Closed Varieties of Posemigroups

In this paper we extend a result of Scheiblich by showing that variety of po-normal bands is closed. We also extend the well known results to posemigroups namely, that pogroups and inverse posemigroups have special amalgamation property in the category of all posemigroups and commutative posemigroups, respectively. Finally, we find some varieties of posemigroups which are closed if they are self convex.

Keywords:

Posemigroup , Dominion , Zigzag Inequalities , Permutative , variety