THE NATURAL PARTIAL ORDER ON SOME TRANSFORMATION SEMIGROUPS

Autor: Pattanachai Rawiwan, Sureeporn Chaopraknoi, Teeraphong Phongpattanacharoen
Rok vydání: 2013
Předmět:
Zdroj: Bulletin of the Australian Mathematical Society. 89:279-292
ISSN: 1755-1633
0004-9727
DOI: 10.1017/s0004972713000580
Popis: For a semigroup $S$, let ${S}^{1} $ be the semigroup obtained from $S$ by adding a new symbol 1 as its identity if $S$ has no identity; otherwise let ${S}^{1} = S$. Mitsch defined the natural partial order $\leqslant $ on a semigroup $S$ as follows: for $a, b\in S$, $a\leqslant b$ if and only if $a= xb= by$ and $a= ay$ for some $x, y\in {S}^{1} $. In this paper, we characterise the natural partial order on some transformation semigroups. In these partially ordered sets, we determine the compatibility of their elements, and find all minimal and maximal elements.
Databáze: OpenAIRE