Question 2
Determine all functions $f: \mathbb{Z} \rightarrow \mathbb{Z}$ with the property that
$$
f(x-f(y))=f(f(x))-f(y)-1
$$
holds for all $x, y \in \mathbb{Z}$.
$$
f(x-f(y))=f(f(x))-f(y)-1
$$
holds for all $x, y \in \mathbb{Z}$.
IMO 2015 — Complete Shortlist Question 2
IMO Shortlist · IMO 2015 — Complete Shortlist