Definition:Infix Notation/Binary Relation

Definition
Let $\RR \subseteq S \times T$ be a binary relation.

When $\tuple {s, t} \in \RR$, we can write either:
 * $\map \RR {s, t}$

or
 * $s \mathrel \RR t$

The notation $s \mathrel \RR t$ is known as infix notation.