Partial orders on semigroups of partial transformations with restricted range

Let X be any set and P(X) the set of all partial transformations defined on X, that is, all functions α:A→B where A,B are subsets of X. Then P(X) is a semigroup under composition. Let Y be a subset of X. Recently, Fernandes and Sanwong defined PT(X,Y)={α P(X):XαY } and defined I(X,Y) to be the set o...

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Bibliographic Details
Main Authors: Sangkhanan K., Sanwong J.
Format: Article
Language:English
Published: 2014
Online Access:http://www.scopus.com/inward/record.url?eid=2-s2.0-84864870168&partnerID=40&md5=40abf6b4a2588b4068d282144e2bffe4
http://cmuir.cmu.ac.th/handle/6653943832/6743
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Institution: Chiang Mai University
Language: English
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Summary:Let X be any set and P(X) the set of all partial transformations defined on X, that is, all functions α:A→B where A,B are subsets of X. Then P(X) is a semigroup under composition. Let Y be a subset of X. Recently, Fernandes and Sanwong defined PT(X,Y)={α P(X):XαY } and defined I(X,Y) to be the set of all injective transformations in PT(X,Y). Hence PT(X,Y) and I(X,Y) are subsemigroups of P(X). In this paper, we study properties of the so-called natural partial order ≥ on PT(X,Y) and I(X,Y) in terms of domains, images and kernels, compare ≥ with the subset order, characterise the meet and join of these two orders, then find elements of PT(X,Y) and I(X,Y) which are compatible. Also, the minimal and maximal elements are described. © 2012 Australian Mathematical Publishing Association Inc.