theorem
  vector(LC_RLSpace(V),L1) - vector(LC_RLSpace(V),L2) = L1 - L2
proof
  - L2 in LinComb(V) by Def14;
  then
A1: - L2 in LC_RLSpace(V);
  - vector(LC_RLSpace(V),L2) = - L2 by Th64
    .= vector(LC_RLSpace(V),- L2) by A1,Def1;
  hence thesis by Th62;
end;
