Hostname: page-component-cd9895bd7-dk4vv Total loading time: 0 Render date: 2024-12-26T00:53:08.087Z Has data issue: false hasContentIssue false

Restrictive Semigroups of Continuous Functions on 0-Dimensional Spaces

Published online by Cambridge University Press:  20 November 2018

Robert D. Hofer*
Affiliation:
State University College of Arts and Science, Plattsburgh, New York
Rights & Permissions [Opens in a new window]

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Let X be a topological space and Y a nonempty subspace of X. Γ(X, Y) denotes the semigroup under composition of all closed self maps of X which carry Y into Y, and is referred to as a restrictive semigroup of closed functions. Similarly, S(X, Y) is the analogous semigroup of continuous selfmaps of X, and is referred to as a restrictive semigroup of continuous functions. It is immediate that each homeomorphism from X onto U which carries the subspace Y of X onto the subspace V of U induces an isomorphism between Γ(X, Y) and Γ(U, V), and also an isomorphism between S(X, Y) and S(U, V). Indeed, one need only map f onto h o f o h-1. An isomorphism of this form is called representable. In [5, Theorem (3.1), p. 1223] it was shown that in most cases, each isomorphism from Γ(X, Y) onto Γ(U, V) is representable. The analogous problem was discussed for the semigroup S(X, Y) and it was pointed out by means of an example that one could not hope to obtain the same result for these semigroups without some further restrictions.

Type
Research Article
Copyright
Copyright © Canadian Mathematical Society 1972

References

1. Beidleman, J. C., On groups and their near-rings 0﹜ junctions, Amer. Math. Monthly 73 (1966), 981983.Google Scholar
2. Clifford, A. H. and Preston, G. B., The algebraic theory of semigroups, Mathematical surveys, Number 7 (Amer. Math. Soc, Providence, R.I., 1961).Google Scholar
3. Magill, K. D., Jr., Another S-admissible class of spaces, Proc. Amer. Math. Soc. 18 (1967), 295298.Google Scholar
4. Magill, K. D., Semigroup structures for families of functions I and II, J. Austral. Math. Soc. 7 (1967), 81107.Google Scholar
5. Magill, K. D., Restrictive semigroups of closed functions, Can. J. Math 20 (1968), 12151229.Google Scholar