# Definition:Infix Notation

## Definition

### Binary Relations

Let $\mathcal R \subseteq S \times T$ be a binary relation.

When $\left({s, t}\right) \in \mathcal R$, we can write either:

$\mathcal R \left({s, t}\right)$

or

$s \mathop {\mathcal R} t$

The notation $s \mathop {\mathcal R} t$ is known as infix notation.

### Binary Operations

Let $\circ: S \times T \to U$ be a binary operation.

When $\map \circ {x, y} = z$, it is common to put the symbol for the operation between the two operands:

$z = x \circ y$

This convention is called infix notation.