<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><!-- $Id$ --><HTML><HEAD> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <TITLE>ZF/README</TITLE></HEAD><BODY><H2>ZF: Zermelo-Fraenkel Set Theory</H2>This directory contains the ML sources of the Isabelle system forZF Set Theory, based on FOL.<p>There are several subdirectories of examples:<DL><DT>AC<DD>subdirectory containing proofs from the book "Equivalents of the Axiomof Choice, II" by H. Rubin and J.E. Rubin, 1985. Thanks to KrzysztofGr`abczewski.<P><DT>Coind<DD>subdirectory containing a large example of proof by co-induction. Itis by Jacob Frost following a paper by Robin Milner and Mads Tofte.<P><DT>IMP<DD>subdirectory containing a semantics equivalence proof betweenoperational and denotational definitions of a simple programming language.Thanks to Heiko Loetzbeyer & Robert Sandner.<P><DT>Resid<DD>subdirectory containing a proof of the Church-Rosser Theorem. It isby Ole Rasmussen, following the Coq proof by G�ard Huet.<P><DT>ex<DD>subdirectory containing various examples.</DL>Isabelle/ZF formalizes the greater part of elementary set theory,including relations, functions, injections, surjections, ordinals andcardinals. Results proved include Cantor's Theorem, the RecursionTheorem, the Schroeder-Bernstein Theorem, and (assuming AC) theWellordering Theorem.<P>Isabelle/ZF also provides theories of lists, trees, etc., forformalizing computational notions. It supports inductive definitionsof infinite-branching trees for any cardinality of branching.<P>Useful references for Isabelle/ZF:<UL><LI> Lawrence C. Paulson,<BR> Set theory for verification: I. From foundations to functions.<BR> J. Automated Reasoning 11 (1993), 353-389.<LI> Lawrence C. Paulson,<BR> Set theory for verification: II. Induction and recursion.<BR> Report 312, Computer Lab (1993).<BR><LI> Lawrence C. Paulson,<BR> A fixedpoint approach to implementing (co)inductive definitions. <BR> In: A. Bundy (editor),<BR> CADE-12: 12th International Conference on Automated Deduction,<BR> (Springer LNAI 814, 1994), 148-161.</UL>Useful references on ZF set theory:<UL><LI> Paul R. Halmos, Naive Set Theory (Van Nostrand, 1960)<LI> Patrick Suppes, Axiomatic Set Theory (Dover, 1972)<LI> Keith J. Devlin,<BR> Fundamentals of Contemporary Set Theory (Springer, 1979)<LI> Kenneth Kunen<BR> Set Theory: An Introduction to Independence Proofs<BR> (North-Holland, 1980)</UL></BODY></HTML>