(* Title: HOL/ex/sum.thy ID: $Id$ Author: Tobias Nipkow Copyright 1994 TU Muenchen A summation operator *) NatSum = Arith + consts sum :: "[nat=>nat, nat] => nat" rules sum_0 "sum(f,0) = 0" sum_Suc "sum(f,Suc(n)) = f(n) + sum(f,n)" end