fact: Definition φ' (xn: nat) : nat := match Cantor.of_nat xn with | (x, 0) => φ x | (x, 1) => c2 (φ x) | (x, 2) => φ x * φ x + φ x + 1 | (x, 3) => φ x * φ x | (x, 4) => c2 (c2 (φ x)) | _ => 0 end.
imports: List Lia Cantor ssreflect ssrbool ssrfun Undecidability.DiophantineConstraints.H10C