Injective Function

• Definition: A function $f:A\to B$ is injective if distinct elements of $A$ map to distinct elements of $B$.
• Formally: $f(x_1)=f(x_2)\Rightarrow x_1=x_2$
• Meaning: No two inputs share the same output.
• Example: $f(x)=2x$ from $\mathbb{Z}\to \mathbb{Z}$ is injective.