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Monadic second order finite satisfiability and unbounded tree-width

Kotek, Tomer ; Veith, Helmut ; Zuleger, Florian

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• Titolo:
Monadic second order finite satisfiability and unbounded tree-width
• Autore: Kotek, Tomer ; Veith, Helmut ; Zuleger, Florian
• Note di contenuto: The finite satisfiability problem of monadic second order logic is decidable only on classes of structures of bounded tree-width by the classic result of Seese (1991). We prove the following problem is decidable: Input: (i) A monadic second order logic sentence $\alpha$, and (ii) a sentence $\beta$ in the two-variable fragment of first order logic extended with counting quantifiers. The vocabularies of $\alpha$ and $\beta$ may intersect. Output: Is there a finite structure which satisfies $\alpha\land\beta$ such that the restriction of the structure to the vocabulary of $\alpha$ has bounded tree-width? (The tree-width of the desired structure is not bounded.) As a consequence, we prove the decidability of the satisfiability problem by a finite structure of bounded tree-width of a logic extending monadic second order logic with linear cardinality constraints of the form $|X_{1}|+\cdots+|X_{r}|<|Y_{1}|+\cdots+|Y_{s}|$, where the $X_{i}$ and $Y_{j}$ are monadic second order variables. We prove the decidability of a similar extension of WS1S.
• Soggetti: Computer Science - Logic In Computer Science ; F.4.1
• Tipo: Articolo
• Identificativo: Arxiv ID: 1505.06622
• Fonte: Cornell University