proposition: Lemma head_of_fdist_rV_belast_last (R: realType) (A : finType) (n : nat) (P : R.-fdist 'rV[A]_n.+2) : head_of_fdist_rV ((fdist_belast_last_of_rV P)`1) = @head_of_fdist_rV R _ _ P.
proof: Proof. rewrite /head_of_fdist_rV /fdist_fst /fdist_prod_of_rV /fdist_belast_last_of_rV. rewrite !fdistmap_comp; congr (fdistmap _ P). rewrite boolp.funeqE => /= v /=. rewrite /rbelast mxE; congr (v ord0 _); exact: val_inj. Qed.
imports: mathcomp(all_ssreflect ssralg fingroup perm matrix) mathcomp(all_algebra vector reals normedtype) mathcomp(mathcomp_extra boolp) mathcomp(Rstruct) ssrR logb realType_ext ssr_ext ssralg_ext bigop_ext