Polymorphic Π1 Types
نویسنده
چکیده
By polymorphic Π1 types we mean types of the polymorphic lambda calculus (system F) in which Π only occurs positively. For such types the question of inhabitation is decidable and observational equivalence corresponds to βη-equivalence and is representable by a term. Furthermore, in the PER-model based on untyped λ-terms universality holds for all Π1 types (all elements can be typed). At the end we consider some possible generalisations of these results.
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