import Mathlib.Tactic
/-!
# International Mathematical Olympiad 1992, Problem 2
Determine all functions f : ℝ → ℝ such that
for all x,y ∈ ℝ, f(x² + f(y)) = y + (f(x))².
-/
namespace Imo1992P2
/- determine -/ abbrev solution_set : Set (ℝ → ℝ) := sorry
theorem imo1992_p2 (f : ℝ → ℝ) :
f ∈ solution_set ↔
∀ x y, f (x^2 + f y) = y + f x ^ 2 := sorry
end Imo1992P2
This problem has a complete formalized solution.