proposition: Lemma im_transversal_repr x0 : transversal_repr x0 X @: P = X.
proof: Proof. rewrite -{2}[X]imset_id -pblock_transversal -imset_comp. by apply: eq_in_imset; apply: pblockK. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop)