Abstract
As a notion dual to Knuth's nested formulas [4], we call a boolean formula\(\Phi = \mathop \wedge \limits_{i = 1}^n c_i \) in conjunctive normal formco-nested if its clauses can be linearly ordered (sayC={c i ;i=1,2, ...,n})so that the graphG cl Φ =(X∪C, {xc i ;x∈c i or ¬x∈c i } ∪ {c i c i+1;i=1, 2, ...,n}) allows a noncrossing drawing in the plane so that the circlec 1,c 2, ...,c n bounds the outerface. Our main result is that maximum satisfiability of co-nested formulas can be decided in linear time.
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Both authors acknowledge a partial support of Ec Cooperative Action IC-1000 (project ALTEC:Algorithms for Future Technologies).
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Kratochvíl, J., Křivánek, M. Satisfiability of co-nested formulas. Acta Informatica 30, 397–403 (1993). https://doi.org/10.1007/BF01209713
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DOI: https://doi.org/10.1007/BF01209713