disjunction

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disjunction A logical expression of the form a1 ∨ a2 ∨ … ∨ an

where ∨ is the OR operation. A particular disjunction of interest is the disjunctive normal form of a Boolean expression involving n variables, x1, x2,…, xn. Each ai is then of the form (y1 ∧ y2 ∧ … yn)

where ∧ is the AND operation and each yi is equal to xi or the complement of xi. Reducing expressions to disjunctive normal form provides a ready method of determining the equivalence of two Boolean expressions. See also propositional calculus. Compare conjunction.

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