Question 14
Determine all injective functions $f: \mathbb{Z} \to \mathbb{Z}$ that satisfy
$$
|f(x) - f(y)| \le |x - y|,
$$
for all $x, y \in \mathbb{Z}$.
$$
|f(x) - f(y)| \le |x - y|,
$$
for all $x, y \in \mathbb{Z}$.
MathNet 2013 Question 14
Math Olympiad Vault · MathNet 2013