| Clausal Normal Form |
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Information AboutClausal Normal Form |
| CATEGORIES ABOUT CLAUSAL NORMAL FORM | |
| logic programming | |
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The procedure begins with any formula of classical First-order Logic : # Put the formula into Negation Normal Form . # Skolemize -- replace Existential variables with Skolem constants or Skolem functions of Universal variables, from the outside inward. Make the following replacements:
# Remove the Quantifiers . # Put the formula into Conjunctive Normal Form . # Replace with . Each conjunct is of the form , which is equivalent to .
# Finally, replace each conjunct with . When n=1, the logic is called Horn Clause logic and is equivalent in computational power to a Universal Turing Machine . Often it is sufficient to generate an equisatisfiable (not an equivalent) CNF for a formula. In this case, the worst-case exponential blow-up can be avoided by introducing ''definitions'' and using them to ''rename'' parts of the formula. |
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