Abstract
For each subchain X′ of a chain X, let T RE (X,X′) denote the semigroup under composition of all full regressive transformations, α:X→X′ satisfying xα≤x for all x∈X. Necessary and sufficient conditions for T RE (X,X′) and T RE (Y,Y′) to be isomorphic are given. This isomorphism theorem is applied to classify the semigroup of regressive transformations T RE (X,X′) where X is one of several familiar subchains of ℝ, the chain of real numbers.
Similar content being viewed by others
References
Adeleke, S.A., Neumann, P.M.: Relations related to betweenness: their structure and automorphisms. Mem. Am. Math. Soc. 623, 131 (1998)
Saito, T., Aoki, K., Kajitori, K.: Remarks on isomorphisms of regressive transformation semigroups. Semigroup Forum 53, 129–134 (1996)
Symons, J.S.V.: Some results concerning a transformation semigroup. J. Aust. Math. Soc. A 19, 413–425 (1975)
Udomkavanich, P., Jitjankarn, P.: Some isomorphism theorems on regressive transformation semigroups. SEA Bull. Math. 29, 581–591 (2005)
Udomkavanich, P., Jitjankarn, P.: Isomorphism theorems of regressive partial transformation semigroups. Int. J. Pure Appl. Math. 18, 207–212 (2005)
Umar, A.: Semigroups of order-decreasing transformations: the isomorphism theorem. Semigroup Forum 53, 220–224 (1996)
Umar, A.: On certain infinite semigroups of order-decreasing transformations I. Commun. Algebra 25(9), 2987–2999 (1997)
Acknowledgements
The authors would like to thank the anonymous referees for helpful comments to improve the manuscript. Their constructive and detailed suggestions are very much appreciated.
Author information
Authors and Affiliations
Corresponding author
Additional information
Communicated by Jorge Almeida.
Rights and permissions
About this article
Cite this article
Udomkavanich, P., Jitjankarn, P. A classification of regressive transformation semigroups on chains. Semigroup Forum 85, 559–570 (2012). https://doi.org/10.1007/s00233-012-9438-7
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00233-012-9438-7