http://repub.eur.nl/res/aut/712/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/1502/ 1990-01-01T00:00:00Z We show that the technique to prove equivalence of operational and denotational cpo based semantics using retractions, as introduced in de Bruin & Vink [1989] for a sequential backtracking language, can be applied to parallel languages as well. We prove equivalence for a uniform language in which procedure calls need not be guarded. The unguardedness is taken care of by giving a semantics in which the nondeterminism is demonic. http://repub.eur.nl/res/pub/1505/ 1989-01-01T00:00:00Z We present an operational model O and a continuation based denotational model D for a uniform variant of PROLOG, including the cut operator. The two semantical definitions make use of higher order transformations Phi and Psi, respectively. We prove O and D equivalent in a novel way by comparing yet another pair of higher order transformations Phi~ and Psi~, that yield Phi and Psi, respectively, by application of a suitable abstraction operator. http://repub.eur.nl/res/pub/1507/ 1989-01-01T00:00:00Z We present a denotational continuation semantics for PROLOG with cut. First a uniform language B is studied, which captures the control flow aspects of PROLOG. The denotational semantics for B is proven equivalent to a transition system based operational semantics. The congruence proof relies on the representation of the operational semantics as a chain of approximations and on a convenient induction principle. Finally, we interpret the abstract language B such that we obtain equivalent denotational and operational models for PROLOG itself.