Hereditary First-Order Logic: the tractable quantifier prefix classes

Fuente: arXiv
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Autori principali: Bodirsky, Manuel, Guzmán-Pro, Santiago
Natura: Preprint
Pubblicazione: 2024
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author Bodirsky, Manuel
Guzmán-Pro, Santiago
author_facet Bodirsky, Manuel
Guzmán-Pro, Santiago
contents Many computational problems can be modelled as the class of all finite structures $\mathbb A$ that satisfy a fixed first-order sentence $ϕ$ hereditarily, i.e., we require that every (induced) substructure of $\mathbb A$ satisfies $ϕ$. We call the corresponding computational problem the hereditary model checking problem for $ϕ$, and denote it by Her$(ϕ)$. We present a complete description of the quantifier prefixes for $ϕ$ such that Her$(ϕ)$ is in P; we show that for every other quantifier prefix there exists a formula $ϕ$ with this prefix such that Her$(ϕ)$ is coNP-complete. Specifically, we show that if $Q$ is of the form $\forall^\ast\exists\forall^\ast$ or of the form $\forall^\ast\exists^\ast$, then Her$(ϕ)$ can be solved in polynomial time whenever the quantifier prefix of $ϕ$ is $Q$. Otherwise, $Q$ contains $\exists \exists \forall$ or $\exists \forall \exists$ as a subword, and in this case, there is a first-order formula $ϕ$ whose quantifier prefix is $Q$ and Her$(ϕ)$ is coNP-complete. Moreover, we show that there is no algorithm that decides for a given first-order formula $ϕ$ whether Her$(ϕ)$ is in P (unless P$=$NP).
format Preprint
id arxiv_https___arxiv_org_abs_2411_10860
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Hereditary First-Order Logic: the tractable quantifier prefix classes
Bodirsky, Manuel
Guzmán-Pro, Santiago
Logic
Computational Complexity
Discrete Mathematics
Logic in Computer Science
03B16, 03B70, 03C13
F.1.3; F.4.1
Many computational problems can be modelled as the class of all finite structures $\mathbb A$ that satisfy a fixed first-order sentence $ϕ$ hereditarily, i.e., we require that every (induced) substructure of $\mathbb A$ satisfies $ϕ$. We call the corresponding computational problem the hereditary model checking problem for $ϕ$, and denote it by Her$(ϕ)$. We present a complete description of the quantifier prefixes for $ϕ$ such that Her$(ϕ)$ is in P; we show that for every other quantifier prefix there exists a formula $ϕ$ with this prefix such that Her$(ϕ)$ is coNP-complete. Specifically, we show that if $Q$ is of the form $\forall^\ast\exists\forall^\ast$ or of the form $\forall^\ast\exists^\ast$, then Her$(ϕ)$ can be solved in polynomial time whenever the quantifier prefix of $ϕ$ is $Q$. Otherwise, $Q$ contains $\exists \exists \forall$ or $\exists \forall \exists$ as a subword, and in this case, there is a first-order formula $ϕ$ whose quantifier prefix is $Q$ and Her$(ϕ)$ is coNP-complete. Moreover, we show that there is no algorithm that decides for a given first-order formula $ϕ$ whether Her$(ϕ)$ is in P (unless P$=$NP).
title Hereditary First-Order Logic: the tractable quantifier prefix classes
topic Logic
Computational Complexity
Discrete Mathematics
Logic in Computer Science
03B16, 03B70, 03C13
F.1.3; F.4.1
url https://arxiv.org/abs/2411.10860