Abstract
We study two kinds of combined modal logics, semiproducts and products with \({\mathbf{S5}}\), and their connection with modal predicate logics. We present examples of propositional modal logics, for which semiproducts or products with \({\mathbf{S5}}\) are axiomatized in the minimal way (they are called semiproduct- or product-matching with \({\mathbf{S5}}\)) and also present counterexamples for these properties. The finite model property for (semi)products, together with (semi)product-matching, allow us to obtain decidability of corresponding 1-variable modal predicate logics.
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Notes
Usually, \({\mathbf{QK}}\), \({\mathbf{Q}\boldsymbol\Lambda }\), and \({\mathbf{Q}\boldsymbol\Lambda \mathbf{C}}\) denote modal logics in the language with predicate letters of every arity, but in this paper we use the same notation for the monadic fragments of those logics.
These are probably the largest known decidable fragments of modal predicate logics; most of 2-variable fragments, even in signatures with a single monadic predicate letter, are undecidable [8].
This fact can also be inferred from Fig. 2.
REFERENCES
K. Segerberg, “Two-dimensional modal logic,” J. Philos. Logic 2 (1), 77–96 (1973).
V. B. Shehtman, “Two-dimensional modal logics,” Math. Notes USSR Acad. Sci. 23, 417–424 (1978).
D. Gabbay, A. Kurucz, F. Wolter, and M. Zakha-ryaschev, Many-Dimensional Modal Logics: Theory and Applications (Elsevier, New York, 2003).
A. Kurucz, “Combining modal logics,” in Handbook of Modal Logic, Ed. by P. Blackburn, J. Van Benthem, and F. Wolter (Elsevier, 2008), pp. 869–924.
G. Fischer-Servi, “On modal logic with an intuitionistic base,” Studia Logica 36, 141–149 (1977).
D. Gabbay and V. Shehtman, “Products of modal logics, Part 1,” Logic J. IGPL 6 (1), 73–146 (1998).
F. Wolter and M. Zakharyaschev, “Decidable fragments of first-order modal logics,” J. Symb. Logic 66 (3), 1415–1438 (1999).
M. Rybakov and D. Shkatov, “Undecidability of first-order modal and intuitionistic logics with two variables and one monadic predicate letter,” Studia Logica 107 (4), 695–717 (2019).
V. Shehtman and D. Shkatov, “On one-variable fragments of modal predicate logics,” Proceedings of SYSMICS 2019 (Univ. of Amsterdam, Amsterdam, 2019), pp. 129–132.
V. Shehtman, “Simplicial semantics and one-variable fragments of modal predicate logics,” Abstracts of Topology, Algebra, and Categories in Logic 2019 (Nice, 2019), pp. 172–173.
V. Shehtman, “On Kripke completeness of modal predicate logics around quantified K5,” Ann. Pure Appl. Logic 174 (2), 103202 (2023).
M. Kracht, Tools and Techniques in Modal Logic (Elsevier, New York, 1999).
V. Shehtman and D. Shkatov, “Kripke (in)completeness of predicate modal logics with axioms of bounded alternativity,” Proceedings of FOMTL 2023 (ESSLLI, 2023), pp. 26–29.
D. Gabbay, V. Shehtman, and D. Skvortsov, Quantification in Nonclassical Logic (Elsevier, New York, 2009), Vol. 1.
V. Shehtman, “Segerberg squares of modal logics and theories of relation algebras,” in Larisa Maksimova on Implication, Interpolation, and Definability, Ed. by S. Odintsov (Springer, Cham, 2018), pp. 245–296.
V. B. Shehtman, “Bisimulation games and locally tabular logics,” Russ. Math. Surv. 71, 979–982 (2016).
ACKNOWLEDGMENTS
We thank an anonymous reviewer for the comments that helped to improve the paper.
Funding
The work of the first author was carried out at Steklov Mathematical Institute and supported by the Russian Scientific Foundation, project no. 21-11-00318.
The work on Sections 1, 2, and 5 has been carried out by the first author; the work on Sections 2, 4, and 6 by the second author.
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Shehtman, V.B., Shkatov, D. Semiproducts, Products, and Modal Predicate Logics: Some Examples. Dokl. Math. 108, 411–418 (2023). https://doi.org/10.1134/S1064562423701296
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DOI: https://doi.org/10.1134/S1064562423701296