proposition: Lemma dprojIdef d d' t s : dproj d s (dproj d' s t) = dproj d s t.
proof: Proof. apply/rowP => b; case/boolP : (b \in s) => Hb; by [rewrite !dproj_in | rewrite dproj_out // dproj_out]. Qed.
imports: mathcomp(all_ssreflect ssralg fingroup finalg zmodp matrix) Reals mathcomp(Rstruct) ssr_ext ssralg_ext ssrR Reals_ext f2 summary subgraph_partition tanner tanner_partition fdist channel checksum