HOL2P - A System of Classical Higher Order Logic with Second Order Polymorphism

Abstract. This paper introduces the logical system HOL2P that extends classical higher order logic (HOL) with type operator variables and universal types. HOL2P has explicit term operations for type abstraction and type application. The formation of type application terms t [ T ] is restricted to small types T that do not contain any universal types. This constraint ensures the existence of a set-theoretic model and thus consistency. The expressiveness of HOL2P allows category-theoretic concepts such as natural transformations and initial algebras to be applied at the level of polymorphic HOL functions. The parameterisation of terms with type operators adds genericity to theorems. Type variable quantification can also be expressed. A prototype of HOL2P has been implemented on top of HOL-Light. Type inference is semi-automatic, and some type annotations are necessary. Reasoning is supported by appropriate tactics. The implementation has been used to check some sample derivations.

• Type: Conference
• Year: 2007
• Where: TPHOL
• Authors: Norbert Völker
• Keywords: Artificial Intelligence, TPHOL 2007, Type Application, Type Operator Variables, Type Operators