The intersection-types discipline for λ-calculus was introduced in Coppo and Dezani-Ciancaglini (1980) as an extension of Curry's type assignment system. The motivation was essentially to increase the class of terms possessing types. Indeed, it turned out that this discipline can assign types to all and only the strongly normalising terms. This is largely a folklore result; the first published proof appears in Pottinger (1980). Subsequently, the intersection-types discipline was used in Barendregt et al. (1983) as a tool for proving Scott's conjecture concerning the completeness of the set-theoretic semantics for simple types.