turned translation for 1::nat into def.
introduced 1' and replaced most occurrences of 1 by 1'.
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<H2>AC -- Equivalents of the Axiom of Choice</H2>
Krzysztof Grabczewski has mechanized the first two chapters of the book
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@book{rubin&rubin,
author = "Herman Rubin and Jean E. Rubin",
title = "Equivalents of the Axiom of Choice, {II}",
publisher = "North-Holland",
year = 1985}
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The report
<A HREF="http://www.cl.cam.ac.uk/Research/Reports/TR377-lcp-mechanising-set-theory.ps.gz">Mechanizing Set Theory</A>, by Paulson and Grabczewski, describes both this development and ZF's theories of cardinals.
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