⟸
Symbol  Format  Data 

⟸  Code Point 
U+27F8 
TeX 
\impliedby 

SVG 
In math, the “long left double arrow symbol” or “implied by” symbol is used to
The reverse implies symbol is used in math to represent a logical implication in the reverse direction. It signifies that if the second statement is true, then the first statement must also be true.
The long left arrow symbol.
The if and only if symbol is used as a logical statement.