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biconditional A logical statement combining two statements, truth values, or formulas P and Q in such a way that the outcome is true only if P and Q are both true or both false, as indicated in the table.

The biconditional connective can be represented by ≡ — <—> or <=>

and is read as “if and only if” or “iff” or “is equivalent to”. Note that P Q has the same truth table as the conjunction (PQ) ∧ (QP)

where → denotes a simple conditional. The biconditional connective itself is also known as the biconditional.