Author: Lawrence C Paulson, Cambridge University Computer Laboratory Copyright 1991 University of Cambridge This is a version of Constructive Type Theory (extensional equality, no universes). Useful references on Constructive Type Theory: B. Nordström, K. Petersson and J. M. Smith, Programming in Martin-Löf's Type Theory (Oxford University Press, 1990) Simon Thompson, Type Theory and Functional Programming (Addison-Wesley, 1991)