proposition: Lemma dE (x : set A) (gX : g @` setT `<=` x `|` y) (ge : forall i : 'I_n, x (g i) -> e i = 0) i : d gX ge i = if g i \in y then e i else 0.
proof: Proof. by rewrite /d; unlock; rewrite ffunE. Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg fingroup perm matrix) mathcomp(mathcomp_extra boolp classical_sets Rstruct) mathcomp(ssrnum ereal) mathcomp(lra Rstruct reals) Reals ssrR Reals_ext Ranalysis_ext ssr_ext ssralg_ext logb realType_ext fdist