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

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

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

disjunction The separation of homologous chromosomes at the anaphase stage of mitosis and meiosis, and movement towards the poles of the nuclear spindle.

disjunction The separation of homologous chromosomes at the anaphase stage of mitosis and meiosis, and movement towards the poles of the nuclear spindle.