Dominions, zigzags and epimorphisms for partially ordered semigroups
Sohail Nasir, Lauri Tart · Acta et Commentationes Universitatis Tartuensis de Mathematica · 2014
We prove an analogue of Isbell's celebrated zigzag theorem for partially ordered semigroups. This theorem provides a useful description of dominions which we employ to describe absolute closedness of posemigroups and epimorphisms in varieties of absolutely closed posemigroups.