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diff --git a/content/zettel/2d2.md b/content/zettel/2d2.md new file mode 100644 index 0000000..83d335a --- /dev/null +++ b/content/zettel/2d2.md @@ -0,0 +1,25 @@ ++++ +title = "Davis–Putnam–Logemann–Loveland (DPLL) algorithm" +author = "Yann Herklotz" +tags = [] +categories = [] +backlinks = ["2d1"] +forwardlinks = ["2d3"] +zettelid = "2d2" ++++ + +This is a backtracking algorithm that is used to solve SAT problems, and +is still used in the most efficient SAT solvers. The two main rules of +reduction are the following: + +Unit propagation +: This consists of removing every clause that contains a unit clause's + literal and discarding the complement of the unit clause's literal. + This can be repeated for a large reduction in the formula. + +Pure literal elimination +: If a pure propositional variable (one where it's complement is not + present anywhere in the formula), is present in a clause, this + clause can also be removed as it can trivially be set to true using + the pure variable. It is therefore not a constraint on the + satisfiability of the system. |