Negation normal form

From formulasearchengine
Revision as of 14:04, 2 January 2012 by (talk) (Undid revision 469124476 by (talk))
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search

Negation normal form is an elementary canonical form in mathematical logic. There are similar requirements for negation normal form in different logic fragments.

In predicate logic, a logical formula is in negation normal form if negation occurs only immediately above elementary propositions, and {} are the only allowed Boolean connectives. In classical logic each formula can be brought into this form by replacing implications and equivalences by their definitions, using De Morgan's laws to push negation inside, and eliminating double negations. This process can be represented using the following rewrite rules:

A formula in negation normal form can be put into the stronger conjunctive normal form or disjunctive normal form by applying the distributivity laws.

External links


de:Negationsnormalform es:Forma normal negativa ja:否定標準形 pt:Forma normal da negação sr:Негацијска нормална форма