A Coalgebraic Semantics of Subtyping

Issue		RAIRO-Theor. Inf. Appl. Volume 35, Number 1, January-February 2001 Coalgebraic Methods in Computer Science


Page(s)		61 - 81
DOI		10.1051/ita:2001109

DOI: 10.1051/ita:2001109

Theoret. Informatics Appl. 35, 61-81 (2001)

Erik Poll

Department of Computer Science, University of Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands.

(Accepted March 9, 2001.)

Abstract
Coalgebras have been proposed as formal basis for the semantics of objects in the sense of object-oriented programming. This paper shows that this semantics provides a smooth interpretation for subtyping, a central notion in object-oriented programming. We show that different characterisations of behavioural subtyping found in the literature can conveniently be expressed in coalgebraic terms. We also investigate the subtle difference between behavioural subtyping and refinement.

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