# Definition:Class Injection

## Definition

Let $A$ and $B$ be classes.

Let $f: A \to B$ be a class mapping from $A$ to $B$.

Then $f$ is said to be a class injection if and only if:

$\forall x_1, x_2 \in A: f \left({x_1}\right) = f \left({x_2}\right) \implies x_1 = x_2$