Polynomial-Time formula classes
نویسنده
چکیده
So far the only method we have to solve the propositional satisfiability problem is to use truth tables, which takes exponential time in the formula size in the worst case. In this lecture we show that for Horn formulas and 2-CNF formulas satisfiability can be decided in polynomial time, whereas for 3-CNF formulas satisfiability is as hard as the general case. We also show that if we replace disjunction in CNF formulas with exclusive-or then satisfiability can again be determined in polynomial time.
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