Low rank MSO

Fuente: arXiv
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Autori principali: Bojańczyk, Mikołaj, Pilipczuk, Michał, Przybyszewski, Wojciech, Sokołowski, Marek, Stamoulis, Giannos
Natura: Preprint
Pubblicazione: 2025
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author Bojańczyk, Mikołaj
Pilipczuk, Michał
Przybyszewski, Wojciech
Sokołowski, Marek
Stamoulis, Giannos
author_facet Bojańczyk, Mikołaj
Pilipczuk, Michał
Przybyszewski, Wojciech
Sokołowski, Marek
Stamoulis, Giannos
contents We introduce a new logic for describing properties of graphs, which we call low rank MSO. This is the fragment of monadic second-order logic in which set quantification is restricted to vertex sets of bounded cutrank. We prove the following statements about the expressive power of low rank MSO. - Over any class of graphs that is weakly sparse, low rank MSO has the same expressive power as separator logic. This equivalence does not hold over all graphs. - Over any class of graphs that has bounded VC dimension, low rank MSO has the same expressive power as flip-connectivity logic. This equivalence does not hold over all graphs. - Over all graphs, low rank MSO has the same expressive power as flip-reachability logic. Here, separator logic is an extension of first-order logic by basic predicates for checking connectivity, which was proposed by Bojańczyk [ArXiv 2107.13953] and by Schirrmacher, Siebertz, and Vigny [ACM ToCL 2023]. Flip-connectivity logic and flip-reachability logic are analogues of separator logic suited for non-sparse graphs, which we propose in this work. In particular, the last statement above implies that every property of undirected graphs expressible in low rank MSO can be decided in polynomial time.
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id arxiv_https___arxiv_org_abs_2502_08476
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Low rank MSO
Bojańczyk, Mikołaj
Pilipczuk, Michał
Przybyszewski, Wojciech
Sokołowski, Marek
Stamoulis, Giannos
Logic in Computer Science
We introduce a new logic for describing properties of graphs, which we call low rank MSO. This is the fragment of monadic second-order logic in which set quantification is restricted to vertex sets of bounded cutrank. We prove the following statements about the expressive power of low rank MSO. - Over any class of graphs that is weakly sparse, low rank MSO has the same expressive power as separator logic. This equivalence does not hold over all graphs. - Over any class of graphs that has bounded VC dimension, low rank MSO has the same expressive power as flip-connectivity logic. This equivalence does not hold over all graphs. - Over all graphs, low rank MSO has the same expressive power as flip-reachability logic. Here, separator logic is an extension of first-order logic by basic predicates for checking connectivity, which was proposed by Bojańczyk [ArXiv 2107.13953] and by Schirrmacher, Siebertz, and Vigny [ACM ToCL 2023]. Flip-connectivity logic and flip-reachability logic are analogues of separator logic suited for non-sparse graphs, which we propose in this work. In particular, the last statement above implies that every property of undirected graphs expressible in low rank MSO can be decided in polynomial time.
title Low rank MSO
topic Logic in Computer Science
url https://arxiv.org/abs/2502.08476