Introduction to Logic

Disjunction

A disjunction is a sequence of sentences separated by occurrences of the ∨ operator and enclosed in parentheses. For example, we can write the disjunction of p and q as (pq).

The constituent sentences of a disjunction are called disjuncts. For example, the disjuncts in the disjunction (pq) are p and q.

The truth value of a disjunction is true if and only if the truth value of at least one of its disjuncts is true; otherwise, the truth value is false.

p q (pq)
1 1 1
1 0 1
0 1 1
0 0 0

Note that this is the inclusive or interpretation of the ∨ operator and is differentiated from the exclusive or interpretation in which a disjunction is true if and only if an odd number of its disjuncts are true.