두 문장이 논리적으로 동치임을 나타내며, 한 문장이 참일 때 오직 그 경우에만 다른 문장도 참이라는 의미를 나타내는 접속사.
A logical connective used to indicate that two statements are equivalent, meaning one is true if and only if the other is also true.
예문:
"A polygon is a triangle iff it has exactly three sides."
"Two sets are equal iff they contain the same elements."
"The matrix is invertible iff its determinant is non-zero."