reserve V for RealLinearSpace;

theorem Th18:
  for L being homogeneous Functional of V, v being VECTOR of V
  holds L.(-v) = - L.v
proof
  let L be homogeneous Functional of V, v be VECTOR of V;
  thus L.(-v) = L.((-1)*v) by RLVECT_1:16
    .= (-1)*L.v by Def3
    .= - L.v;
end;
