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

theorem
  for S being 1-sorted, N being NetStr over S holds N is SubNetStr of N
proof
  let S be 1-sorted, N be NetStr over S;
  N is SubRelStr of N & the mapping of N = (the mapping of N)|the carrier
  of N by Th6;
  hence thesis by Def6;
end;
