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In boolean logic, a disjunctive normal form (DNF) is a canonical normal form of a logical formula consisting of a disjunction of conjunctions; it can also be described as an OR of ANDs, a sum of products, or — in philosophical logic — a cluster concept. [1] As a normal form, it is useful in automated theorem proving.
[8] [9] This provides a procedure for converting between conjunctive normal form and disjunctive normal form. [10] Since the Disjunctive Normal Form Theorem shows that every formula of propositional logic is expressible in disjunctive normal form, every formula is also expressible in conjunctive normal form by means of effecting the conversion ...
Using the laws of Boolean algebra, every propositional logic formula can be transformed into an equivalent conjunctive normal form, which may, however, be exponentially longer. For example, transforming the formula (x 1 ∧y 1) ∨ (x 2 ∧y 2) ∨ ... ∨ (x n ∧y n) into conjunctive normal form yields (x 1 ∨ x 2 ∨ … ∨ x n) ∧
The De Morgan dual is the canonical conjunctive normal form , maxterm canonical form, or Product of Sums (PoS or POS) which is a conjunction (AND) of maxterms. These forms can be useful for the simplification of Boolean functions, which is of great importance in the optimization of Boolean formulas in general and digital circuits in particular.
The self-dual connectives, which are equal to their own de Morgan dual; if the truth values of all variables are reversed, so is the truth value these connectives return, e.g. , maj(p, q, r). The truth-preserving connectives; they return the truth value T under any interpretation that assigns T to all variables, e.g. ∨ , ∧ , ⊤ , → , ↔ ...
A graphical representation of a partially built propositional tableau. In proof theory, the semantic tableau [1] (/ t æ ˈ b l oʊ, ˈ t æ b l oʊ /; plural: tableaux), also called an analytic tableau, [2] truth tree, [1] or simply tree, [2] is a decision procedure for sentential and related logics, and a proof procedure for formulae of first-order logic. [1]
Venn diagram, depicting the truth table values as a colouring of regions of the plane; Algebraically, as a propositional formula using rudimentary Boolean functions: Negation normal form, an arbitrary mix of AND and ORs of the arguments and their complements; Disjunctive normal form, as an OR of ANDs of the arguments and their complements
A logical formula is considered to be in CNF if it is a conjunction of one or more disjunctions of one or more literals.As in disjunctive normal form (DNF), the only propositional operators in CNF are or (), and (), and not ().