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Leibnizian models of set theory

Published online by Cambridge University Press:  12 March 2014

Ali Enayat*
Affiliation:
Department of Mathematics and Statistics, American University, Washington, D.C., 20016-8050, USA, E-mail: [email protected]

Abstract.

A model is said to be Leibnizian if it has no pair of indiscernibles. Mycielski has shown that there is a first order axiom LM (the Leibniz-Mycielski axiom) such that for any completion T of Zermelo-Fraenkel set theory ZF. T has a Leibnizian model if and only if T proves LM. Here we prove:

Theorem A. Every complete theory T extending ZF + LM has nonisomorphic countable Leibnizian models.

Theorem B. If κ is a prescribed definable infinite cardinal ofa complete theory T extending ZF + V = OD, then there are nonisomorphic Leibnizian models of T of power1such thatis ℵ1-like.

Theorem C. Every complete theory T extendingZF + V = ODhas nonisomorphic ℵ1-like Leibnizian models.

Type
Research Article
Copyright
Copyright © Association for Symbolic Logic 2004

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