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Main Authors: Harrison-Trainor, Matthew, Kulshreshtha, Dhruv
Format: Preprint
Published: 2022
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Online Access:https://arxiv.org/abs/2211.03976
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author Harrison-Trainor, Matthew
Kulshreshtha, Dhruv
author_facet Harrison-Trainor, Matthew
Kulshreshtha, Dhruv
contents We work in the setting of Zermelo-Fraenkel set theory without assuming the Axiom of Choice. We consider sets with the Boolean operations together with the additional structure of comparing cardinality (in the Cantorian sense of injections). What principles does one need to add to the laws of Boolean algebra to reason not only about intersection, union, and complementation of sets, but also about the relative size of sets? We give a complete axiomatization. A particularly interesting case is when one restricts to the Dedekind-finite sets. In this case, one needs exactly the same principles as for reasoning about imprecise probability comparisons, the central principle being Generalized Finite Cancellation (which includes, as a special case, division-by-$m$). In the general case, the central principle is a restricted version of Generalized Finite Cancellation within Archimedean classes which we call Covered Generalized Finite Cancellation.
format Preprint
id arxiv_https___arxiv_org_abs_2211_03976
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle The Logic of Cardinality Comparison Without the Axiom of Choice
Harrison-Trainor, Matthew
Kulshreshtha, Dhruv
Logic
03E10
We work in the setting of Zermelo-Fraenkel set theory without assuming the Axiom of Choice. We consider sets with the Boolean operations together with the additional structure of comparing cardinality (in the Cantorian sense of injections). What principles does one need to add to the laws of Boolean algebra to reason not only about intersection, union, and complementation of sets, but also about the relative size of sets? We give a complete axiomatization. A particularly interesting case is when one restricts to the Dedekind-finite sets. In this case, one needs exactly the same principles as for reasoning about imprecise probability comparisons, the central principle being Generalized Finite Cancellation (which includes, as a special case, division-by-$m$). In the general case, the central principle is a restricted version of Generalized Finite Cancellation within Archimedean classes which we call Covered Generalized Finite Cancellation.
title The Logic of Cardinality Comparison Without the Axiom of Choice
topic Logic
03E10
url https://arxiv.org/abs/2211.03976