fact: Definition proper_addvP (S : proper_addv_expr) := let: ProperSumvExpr _ _ termS := S return mxsum_spec (vs2mx S) S in termS.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop finfun tuple) mathcomp(ssralg matrix mxalgebra zmodp)