Z `{Integers Z} Z2 `{Integers Z2} x : integers_to_ring Z2 Z (integers_to_ring Z Z2 x) = x. Proof. change (Compose (integers_to_ring Z2 Z) (integers_to_ring Z Z2) x = id x). apply to_ring_unique_alt;apply _. Qed.
Require Import Require Import Import NatPair.Instances.