On the size of maximum renamable Horn sub-CNF
نویسندگان
چکیده
منابع مشابه
Maximum Renamable Horn sub-CNFs
The NP-hard problem of finding the largest renamable Horn sub-CNF of a given CNF is considered, and a polynomial time approximation algorithm is presented for this problem. It is shown that for cubic CNFs this algorithm has a guaranteed performance ratio of 40 67 .
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We introduce new linear time algorithms for satisfiability of binary propositional theories (2-SAT), and for recognition and satisfiability of renamable Horn theories. The algorithms are based on unit resolution, and are thus likely easier to integrate within general SAT solvers than other graph-based algorithms.
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Yamasaki and Doshita have defined an extension of the class of propositional Horn formulas; later, Gallo and Scutellà generalized this class to a hierarchy Γ0 ⊆ Γ1 ⊆ . . . ⊆ Γk ⊆ . . ., where Γ0 is the set of Horn formulas and Γ1 is the class of Yamasaki and Doshita. For any fixed k, the propositional formulas in Γk can be recognized in polynomial time, and the satisfiability problem for Γk for...
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Many solvers have been designed for QBFs, the validity problem for Quantified Boolean Formulas for the past few years. In this paper, we describe a new branching heuristics whose purpose is to promote renamable Horn formulas. This heuristics is based on Hébrard’s algorithm for the recognition of such formulas. We present some experimental results obtained by our qbf solver Qbfl with the new bra...
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ژورنال
عنوان ژورنال: Discrete Applied Mathematics
سال: 2005
ISSN: 0166-218X
DOI: 10.1016/j.dam.2004.05.007