Episodes in Model-Theoretic Xenology: Rationals as Positive Integers in R#

Open Access
Authors
Publication date 2021
Journal The Australasian Journal of Logic
Article number 9
Volume | Issue number 18 | 5
Pages (from-to) 425-442
Organisations
  • Interfacultary Research - Institute for Logic, Language and Computation (ILLC)
Abstract Meyer and Mortensen’s Alien Intruder Theorem includes the extraordinary observation that the rationals can be extended to a model of the relevant arithmetic R♯, thereby serving as integers themselves. Although the mysteriousness of this observation is acknowledged, little is done to explain why such rationals-as-integers exist or how they operate. In this paper, we show that Meyer and Mortensen’s models can be identified with a class of ultraproducts of finite models of R♯, providing insights into some of the more mysterious phenomena of the rational models.
Document type Article
Note In: A Special Issue on Robert Meyer and Relevant Arithmetic.
Language English
Published at https://doi.org/10.26686/ajl.v18i5.6919
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9+-+Xenology+-+AJL+format+-+Repaginated (Final published version)
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