Modal Pure Type Systems
We present a framework for intensional reasoning in typed λ-calculus. In this family of calculi, called Modal Pure Type Systems (MPTSs), a “propositions-as-types”-interpretation can be given for normal modal logics. MPTSs are an extension of the Pure Type Systems (PTSs) of Barendregt (1992). We show that they retain the desirable meta-theoretical properties of PTSs, and briefly discuss applications in the area of knowledge representation.