Principal Type scheme and unification for intersection type discipline

AbstractThe intersection type discipline for the λ-calculus (ITD) is an extension of the classical functionality theory of Curry. In the ITD a term satisfying a given property has a principal type scheme in an extended meaning, i.e., there is a type scheme deducible for it from which all and only the type schemes deducible for it are reachable, by means of suitable operations. The problem of finding the principal type scheme for a term, if it exists, is semidecidable. In the paper a procedure is shown, building the principal type scheme of a term through the construction of the most general unifier for intersection type schemes