Definition:Conditional/Notational Variants/Sign of Illation

Definition
The sign of illation $-\!\!\!<$ is a notation invented by Charles Sanders Peirce to denote the conditional operator.

Peirce derives $-\!\!\!<$ as a variant of the sign $\le$ for less than or equal to, so as to denote that:
 * $A \mathop {-\!\!\!<} B$

represents the situation such that whenever a particular statement $A$ is true, then so is statement $B$.

It is rarely (if ever) seen nowadays except as a historical curiosity.

Linguistic Note
The word illation derives from the Latin illātiō, whose meaning is logical inference, deduction or conclusion.