A Note on Maximal and Minimal Elements in Semigroups of Partial Transformation Preserving Order and Contraction -

Main Article Content

Chaiwat Namnak

Abstract

For a positive integer n, let [n]={1, 2, 3, ..., n}  and COPn denote the semigroup of all partial transformations that preserve order and a contraction. In this paper, we give a characterization of maximal and minimal elements of COPn  with respect to its natural partial order. 


For a positive integer gif.latex?n, let gif.latex?\left&space;[&space;n&space;\right&space;]&space;=&space;\left&space;\{&space;1,&space;2,&space;3,&space;...&space;,n&space;\right&space;\}, consider the semigroup gif.latex?COP_{n} consisting of all partial transformations gif.latex?\alpha from gif.latex?\left&space;[&space;n&space;\right&space;] to gif.latex?\left&space;[&space;n&space;\right&space;] such that gif.latex?\alpha preserves both a natural partial order gif.latex?\leq ( if gif.latex?x\leq&space;y  then gif.latex?xa\leq&space;ya) and contraction gif.latex?\left&space;(&space;\left&space;|&space;xa&space;-&space;ya&space;\right&space;|\leq&space;\left&space;|&space;x-y&space;\right&space;|&space;\right&space;). In this paper, we give a characterization of maximal and minimal elements of gif.latex?COP_{n} with respect to its natural partial order. 

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References

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