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Unit propagation (UP) or Boolean Constraint propagation or the one-literal rule (OLR) is a procedure of automated theorem proving that can simplify a set of (usually propositional) clauses. ==Definition== The procedure is based on unit clauses, i.e. clauses that are composed of a single literal. Because each clause needs to be satisfied, we know that this literal must be true. If a set of clauses contains the unit clause , the other clauses are simplified by the application of the two following rules: # every clause (other than the unit clause itself) containing is removed (the clause is satisfied if is); # in every clause that contains this literal is deleted ( can not contribute to it being satisfied). The application of these two rules lead to a new set of clauses that is equivalent to the old one. For example, the following set of clauses can be simplified by unit propagation because it contains the unit clause . : Since contains the literal , this clause can be removed altogether. Since contains the negation of the literal in the unit clause, this literal can be removed from the clause. The unit clause is not removed; this would make the resulting set not equivalent to the original one; this clause can be removed if already stored in some other form (see section "Using a partial model"). The effect of unit propagation can be summarized as follows. |} The resulting set of clauses is equivalent to the above one. The new unit clause that results from unit propagation can be used for a further application of unit propagation, which would transform into . 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「unit propagation」の詳細全文を読む スポンサード リンク
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