Guilhem Gamard ; Aliénor Goubault-Larrecq ; Pierre Guillon ; Pierre Ohlmann ; Kévin Perrot et al.
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Hardness of monadic second-order formulae over succinct graphs
lmcs:13799 -
Logical Methods in Computer Science,
January 6, 2026,
Volume 22, Issue 1
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https://doi.org/10.46298/lmcs-22(1:3)2026Hardness of monadic second-order formulae over succinct graphsArticle
Authors: Guilhem Gamard ; Pierre Guillon ; Kévin Perrot ; Guillaume Theyssier
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Guilhem Gamard;Pierre Guillon;Kévin Perrot;Guillaume Theyssier
Our main result is a succinct counterpoint to Courcelle's meta-theorem as follows: every cw-nontrivial monadic second-order (MSO) property is either NP-hard or coNP-hard over graphs given by succinct representations. Succint representations are Boolean circuits computing the adjacency relation. Cw-nontrivial properties are those which have infinitely many models and infinitely many countermodels with bounded cliquewidth. Moreover, we explore what happens when the cw-nontriviality condition is dropped and show that, under a reasonable complexity assumption, the previous dichotomy fails, even for questions expressible in first-order logic.
Volume: Volume 22, Issue 1
Published on: January 6, 2026
Imported on: June 19, 2024
Keywords: Computational Complexity, Logic in Computer Science