\HarrThe \Harr command in LaTeX is used to produce a double-headed arrow pointing both left and right. It is often used to denote logical equivalence or a bidirectional relationship between two statements or expressions.
Logical equivalence between statements A and B
A \Harr BBidirectional relationship between variables x and y
x \Harr yEquivalence of predicates P and Q for variable x
P(x) \Harr Q(x)