lec18

Split conjuncts into a separate clauses 9 standardize

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Unformatted text preview: onjunctive normal form (conjunction of disjunctions) (P ^ Q) ∨ R ==> (P ∨ R) ^ (Q ∨ R) (P ∨ Q) ∨ R ==> (P ∨ Q ∨ R) 8. Split conjuncts into a separate clauses 9. Standardize variables so each clause contains only variable names that do not occur in any other clause CS 460, Session 18 15 EXAMPLE: Convert the following FOL sentence to CNF by applying the 9 steps discussed earlier (∀x) [ P(x) → { (∀y)(P(y) → P(f(x,y))) ∧ ¬(∀y)(Q(x,y) → P(y)) } ] CS 460, Session 18 16 Examples: Converting FOL sentences to clause form… Convert the sentence 1. (∀x)(P(x) → ((∀y)(P(y) → P(f(x,y))) ∧ ¬(∀y)(Q(x,y)→ P(y)))) (like A => B ^ C) 2. Eliminate => (∀x)(¬P(x) ∨ ((∀y)(¬P(y) ∨ P(f(x,y))) ∧ ¬(∀y)(¬Q(x,y) ∨ P(y)))) 3. Reduce scope of negation...
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This note was uploaded on 02/19/2014 for the course CSCI 460 taught by Professor Narayanaswamy during the Spring '08 term at USC.

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