Logical biconditional
In logic and mathematics, the logical biconditional, also known as material biconditional or equivalence or bidirectional implication or biimplication or bientailment or exclusive nor, is the logical connective used to conjoin two statements P {\displaystyle P} and Q {\displaystyle Q} to form the statement " P {\displaystyle P} if and only if Q {\displaystyle Q} " (often abbreviated as " P {\displaystyle P} iff Q {\displaystyle Q} "), where P {\displaystyle P} is known as the antecedent, and Q {\displaystyle Q} the consequent. Nowadays, notations to represent equivalence include ↔ , ⇔ , ≡ {\displaystyle \leftrightarrow ,\Leftrightarrow ,\equiv } .