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2015 On the Decidability of Axiomatized Mereotopological Theories
Hsing-chien Tsai
Notre Dame J. Formal Logic 56(2): 287-306 (2015). DOI: 10.1215/00294527-2864307


The signature of the formal language of mereotopology contains two predicates P and C, which stand for “being a part of” and “contact,” respectively. This paper will deal with the decidability issue of the mereotopological theories which can be formed by the axioms found in the literature. Three main results to be given are as follows: (1) all axiomatized mereotopological theories are separable; (2) all mereotopological theories up to ACEMT, SACEMT, or SACEMT are finitely inseparable; (3) all axiomatized mereotopological theories except SAX, SAX, or SB¯X, where X is strictly stronger than CEMT, are undecidable. Then it can also be easily seen that all axiomatized mereotopological theories proved to be undecidable here are neither essentially undecidable nor strongly undecidable but are hereditarily undecidable. Result (3) will be shown by constructing strongly undecidable mereotopological structures based on two-dimensional Euclidean space, and it will be pointed out that the same construction cannot be carried through if the language is not rich enough.


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Hsing-chien Tsai. "On the Decidability of Axiomatized Mereotopological Theories." Notre Dame J. Formal Logic 56 (2) 287 - 306, 2015.


Published: 2015
First available in Project Euclid: 17 April 2015

zbMATH: 1334.03011
MathSciNet: MR3337381
Digital Object Identifier: 10.1215/00294527-2864307

Primary: 03C99
Secondary: 06F99

Keywords: decidability , finite separability , mereology , mereotopology , separability

Rights: Copyright © 2015 University of Notre Dame

Vol.56 • No. 2 • 2015
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