The role of counting quantifiers in laminar set systems

Fuente: arXiv
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Hauptverfasser: Campbell, Rutger, Köhler, Noleen
Format: Preprint
Veröffentlicht: 2025
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author Campbell, Rutger
Köhler, Noleen
author_facet Campbell, Rutger
Köhler, Noleen
contents Laminar set systems consist of non-crossing subsets of a universe with set inclusion essentially corresponding to the descendant relationship of a tree, the so-called laminar tree. Laminar set systems lie at the core of many graph decompositions such as modular decompositions, split decompositions, and bi-join decompositions. We show that from a laminar set system we can obtain the corresponding laminar tree by means of a monadic second order logic (MSO) transduction. This resolves an open question originally asked by Courcelle and is a satisfying resolution as MSO is the natural logic for set systems and is sufficient to define the property ``laminar''. Using results from Campbell et al. [STACS 2025], we can now obtain transductions for obtaining modular decompositions, co-trees, split decompositions and bi-join decompositions using MSO instead of CMSO. We further gain some insight into the expressive power of counting quantifiers and provide some results towards determining when counting quantifiers can be simulated in MSO in laminar set systems and when they cannot.
format Preprint
id arxiv_https___arxiv_org_abs_2512_02617
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The role of counting quantifiers in laminar set systems
Campbell, Rutger
Köhler, Noleen
Logic in Computer Science
Formal Languages and Automata Theory
Laminar set systems consist of non-crossing subsets of a universe with set inclusion essentially corresponding to the descendant relationship of a tree, the so-called laminar tree. Laminar set systems lie at the core of many graph decompositions such as modular decompositions, split decompositions, and bi-join decompositions. We show that from a laminar set system we can obtain the corresponding laminar tree by means of a monadic second order logic (MSO) transduction. This resolves an open question originally asked by Courcelle and is a satisfying resolution as MSO is the natural logic for set systems and is sufficient to define the property ``laminar''. Using results from Campbell et al. [STACS 2025], we can now obtain transductions for obtaining modular decompositions, co-trees, split decompositions and bi-join decompositions using MSO instead of CMSO. We further gain some insight into the expressive power of counting quantifiers and provide some results towards determining when counting quantifiers can be simulated in MSO in laminar set systems and when they cannot.
title The role of counting quantifiers in laminar set systems
topic Logic in Computer Science
Formal Languages and Automata Theory
url https://arxiv.org/abs/2512.02617