© 1997 by Oxford University Press
A note on logical relations between semantics and syntax
Cambridge University Computer Laboratory, Cambridge CB2 3QG, UK. Email: Andrew.Pitts@cl.cam.ac.uk
This note gives a new proof of the 'operational extensionality' property of Abramsky's lazy lambda calculus-namely the coincidence of contextual equivalence with a co-inductively defined notion of 'applicative bisimilarity'. This purely syntactic results is here proved using a logical relation (due to Plotkin) between the syntax and its denotational semantics. The proof exploits a mixed inductive/coinductive characterisation of the logical relation recently discovered by the author.
Keywords: denotational semantics, logical relation, lambda calculus, contextual equivalence