Definition C_AbelianGroup_mixin :=
  AbelianGroup.Mixin _ _ _ _ Cplus_comm Cplus_assoc Cplus_0_r Cplus_opp_r.Canonical C_AbelianGroup :=
  AbelianGroup.Pack C C_AbelianGroup_mixin C.

Lemma Copp_0 : Copp 0 = 0.