The foundations of program verification (2nd ed.)
The foundations of program verification (2nd ed.)
A note on Dowling and Gallier's top-down algorithm for propositional horn satisfiability
Journal of Logic Programming
Acta Informatica
Extended Horn sets in propositional logic
Journal of the ACM (JACM)
A hierarchy of tractable satisfiability problems
Information Processing Letters
A Complexity Index for Satisfiability Problems
SIAM Journal on Computing
Recognition of q-Horn formulae in linear time
Discrete Applied Mathematics
On finding solutions for extended Horn formulas
Information Processing Letters
New methods for 3-SAT decision and worst-case analysis
Theoretical Computer Science
Renaming a Set of Clauses as a Horn Set
Journal of the ACM (JACM)
On a generalization of extended resolution
Discrete Applied Mathematics - Special issue on the satisfiability problem and Boolean functions
The complexity of theorem-proving procedures
STOC '71 Proceedings of the third annual ACM symposium on Theory of computing
Solving the Resolution-Free SAT Problem by Submodel Propagation in Linear Time
Annals of Mathematics and Artificial Intelligence
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We report a polynomial time SAT problem instance, the Blocked SAT problem. A blocked clause set, an instance of the Blocked SAT problem, contains only blocked clauses. A close is blocked (for resolution) if it has a literal on which no resolution is possible in the clause set. We know from work of O. Kullmann that a blocked clause can be added or deleted from a clause set without changing its satisfiability. Hence, any blocked clause set is satisfiable, but it is not clear how to find a satisfying assignment for it. We introduce the Blocked SAT Solver algorithm, which provides a model for Blocked SAT problems in linear time, if we know at least one blocked literal per clause. To collect these information polynomial time is needed in general. We show that in case of 3-SAT we can collect these information in linear time. This means that the Blocked 3-SAT problem is a linear time problem. We also discuss how to use blocked clauses if the whole clause set is not blocked.