reserve V for RealLinearSpace;

theorem Th20:
  for L being additive Functional of V holds L.(0.V) = 0
proof
  let L be additive Functional of V;
  L.(0.V) + 0 = L.(0.V + 0.V)
    .= L.(0.V) + L.(0.V) by Def2;
  hence thesis;
end;
