Computational Adequacy of the FIX-Logic

Abstract This paper presents computational adequacy results for the FIX logical system introduced by Crole and Pitts in LICS'90. More precisely, we take two simple PCF style languages (whose dynamic semantics follow a call-by-value and call-by-name regime), give translations of the languages into suitable judgements in the FIX-logic and prove that the translations are adequate for the static and dynamic semantics. This shows that the FIX-logic can be regarded as a programming metalogic which will uniformly interpret both call-by-value and call-by-name languages. The proofs of dynamic adequacy make use of a logical relations technique which is based on the methods of Plotkin and Tait. We also show that there is some choice in the translation of recursion; certain translations make use of an existence property of the FIX-logic to prove computational adequacy.