reserve x,y,z,X for set,
  T for Universe;

theorem Th10:
  for S being 1-sorted, N being NetStr over S, M be SubNetStr of N
  holds the carrier of M c= the carrier of N
proof
  let S be 1-sorted, N be NetStr over S, M be SubNetStr of N;
  M is SubRelStr of N by Def6;
  hence thesis by YELLOW_0:def 13;
end;
