Monadic Second-Order Logic of Permutations

Fuente: arXiv
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Autores principales: Jelínek, Vít, Opler, Michal
Formato: Preprint
Publicado: 2025
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author Jelínek, Vít
Opler, Michal
author_facet Jelínek, Vít
Opler, Michal
contents Permutations can be viewed as pairs of linear orders, or more formally as models over a signature consisting of two binary relation symbols. This approach was adopted by Albert, Bouvel and Féray, who studied the expressibility of first-order logic in this setting. We focus our attention on monadic second-order logic. Our results go in two directions. First, we investigate the expressive power of monadic second-order logic. We exhibit natural properties of permutations that can be expressed in monadic second-order logic but not in first-order logic. Additionally, we show that the property of having a fixed point is inexpressible even in monadic second-order logic. Secondly, we focus on the complexity of monadic second-order model checking. We show that there is an algorithm deciding if a permutation $π$ satisfies a given monadic second-order sentence $φ$ in time $f(|φ|, \operatorname{tw}(π)) \cdot n$ for some computable function $f$ where $n = |π|$ and $\operatorname{tw}(π)$ is the tree-width of $π$. On the other hand, we prove that the problem remains hard even when we restrict the permutation $π$ to a fixed hereditary class $\mathcal{C}$ with mild assumptions on $\mathcal{C}$.
format Preprint
id arxiv_https___arxiv_org_abs_2511_02386
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Monadic Second-Order Logic of Permutations
Jelínek, Vít
Opler, Michal
Combinatorics
Logic in Computer Science
Logic
Permutations can be viewed as pairs of linear orders, or more formally as models over a signature consisting of two binary relation symbols. This approach was adopted by Albert, Bouvel and Féray, who studied the expressibility of first-order logic in this setting. We focus our attention on monadic second-order logic. Our results go in two directions. First, we investigate the expressive power of monadic second-order logic. We exhibit natural properties of permutations that can be expressed in monadic second-order logic but not in first-order logic. Additionally, we show that the property of having a fixed point is inexpressible even in monadic second-order logic. Secondly, we focus on the complexity of monadic second-order model checking. We show that there is an algorithm deciding if a permutation $π$ satisfies a given monadic second-order sentence $φ$ in time $f(|φ|, \operatorname{tw}(π)) \cdot n$ for some computable function $f$ where $n = |π|$ and $\operatorname{tw}(π)$ is the tree-width of $π$. On the other hand, we prove that the problem remains hard even when we restrict the permutation $π$ to a fixed hereditary class $\mathcal{C}$ with mild assumptions on $\mathcal{C}$.
title Monadic Second-Order Logic of Permutations
topic Combinatorics
Logic in Computer Science
Logic
url https://arxiv.org/abs/2511.02386