∀ {R : Type u_1} {M : Type u_2} [inst : CommSemiring R] [inst_1 : AddCommMonoid M] [inst_2 : Module R M]
  [inst_3 : Preorder R] [AddLeftMono R] {B C : LinearMap.BilinForm R M},
  B.IsPosSemidef → C.IsPosSemidef → (B + C).IsPosSemidef