* Isar/Pure: emulation of instantiation tactics (rule_tac, cut_tac,
etc.) now consider the syntactic context of assumptions, giving a
better chance to get type-inference of the arguments right (this is
especially important for locales);
* system: refrain from any attempt at filtering input streams; no
longer support ``8bit'' encoding of old isabelle font, instead proper
iso-latin characters may now be used;
(* Title: ZF/Zorn0.thy
ID: $Id$
Author: Lawrence C Paulson, Cambridge University Computer Laboratory
Copyright 1994 University of Cambridge
Based upon the article
Abrial & Laffitte,
Towards the Mechanization of the Proofs of Some
Classical Theorems of Set Theory.
*)
Zorn0 = OrderArith + AC + "inductive" +
consts
Subset_rel :: "i=>i"
increasing :: "i=>i"
chain, maxchain :: "i=>i"
super :: "[i,i]=>i"
rules
Subset_rel_def "Subset_rel(A) == {z: A*A . EX x y. z=<x,y> & x<=y & x~=y}"
increasing_def "increasing(A) == {f: Pow(A)->Pow(A). ALL x. x<=A --> x<=f`x}"
chain_def "chain(A) == {F: Pow(A). ALL X:F. ALL Y:F. X<=Y | Y<=X}"
super_def "super(A,c) == {d: chain(A). c<=d & c~=d}"
maxchain_def "maxchain(A) == {c: chain(A). super(A,c)=0}"
end