gottlob@vexpert.dbai.tuwien.ac.at (Georg Gottlob) (01/06/91)
The satisfiability problem (SAT) and many restricted versions of it (e.g. monotone SAT, planar SAT etc.) remain NP-complete even if |c|<=3 for each clause c in the problem instances. I am looking for restricted versions of SAT (defined by additional syntactic conditions on the problem instances) such that: 1) the restricted version is still NP-complete, and 2) the restricted version is solvable in polynomial time if the cardinality of clauses id bounded by a constant k, i.e., |c|<=k for each clause c in the problem instance. Examples of such classes and/or pointers to relevant references are welcome. -------------------------- Georg Gottlob gottlob@vexpert.dbai.tuwien.ac.at