theorem Th6:
  0.(TOP-REAL n) = 0.(REAL-NS n)
  proof
    thus 0.(TOP-REAL n)
     = 0.(the RLSStruct of TOP-REAL n)
    .= 0.(the RLSStruct of REAL-NS n) by Th1
    .= 0.(REAL-NS n);
  end;
