proposition: Lemma injm_sdpair2 : 'injm sdpair2.
proof: Proof. apply/subsetP=> a /setIP[Da]. by rewrite !inE -val_eqE val_insubd inE Da group1 /=; case/andP. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq div) mathcomp(choice fintype bigop finset fingroup morphism) mathcomp(quotient action)