\iffThe \iff command in LaTeX is used to denote a logical biconditional, which is a connective between statements that is true when both statements are either true or false. It is often read as 'if and only if'. This symbol is commonly used in mathematical logic and proofs to show that two statements are equivalent.
Logical equivalence between statements A and B
A \iff Bx equals 2 if and only if x squared equals 4
x = 2 \iff x^2 = 4Predicate P(n) is true if and only if predicate Q(n) is true
P(n) \iff Q(n)