(* Title: HOL/ex/pl0.thy ID: $Id$ Author: Tobias Nipkow Copyright 1994 TU Muenchen Syntax of propositional logic formulae. *) PL0 = HOL + types 'a pl arities pl :: (term)term consts false :: "'a pl" "->" :: "['a pl,'a pl] => 'a pl" (infixr 90) var :: "'a => 'a pl" ("#_") end