fact: Definition lagrange_fun (n : Z) : (Z * Z) * (Z * Z) := let (a, ha) := lagrange_4_square_theorem (Z.abs n) (Zabs_pos n) in let (b, hb) := ha in let (c, hc) := hb in let (d, _ ) := hc in ((a, b), (c, d)).
imports: ZArith Lia Znumtheory Natsets MyNat Ztools Zeqm Znumfacts