Some computational properties of intersection types

Abstract

This paper presents a new method for comparing computation-properties of /spl lambda/-terms typeable with intersection types with respect to terms typeable with Curry types. In particular, strong normalization and /spl lambda/-definability are investigated. A translation is introduced from intersection typing derivations to Curry typeable terms; the main feature of the proposed technique is that the translation is preserved by /spl beta/-reduction. This allows to simulate a computation starting from a term typeable in the intersection discipline by means of a computation starting from a simply typeable term. Our approach naturally leads to prove strong normalization in the intersection system by means of purely syntactical techniques. In addition, the presented method enables us to give a proof of a conjecture proposed by Leivant in 1990, namely that all functions uniformly definable using intersection types are already definable using Curry types.