%ID: $Id$ %Author: Jia Meng, NICTA %extensionality, untyped input_clause(a18,axiom, [--equal(hAPP(F,hAPP(hAPP(hEXTENT,F),G)),hAPP(G,hAPP(hAPP(hEXTENT,F),G))), ++equal(F,G)]).