reserve n for Nat;

theorem Th3:
  for S be closed Subset of TOP-REAL 2 st S is bounded holds proj1
  .:S is closed
proof
  let S be closed Subset of TOP-REAL 2;
  assume S is bounded;
  then Cl(proj1.:S) = proj1.:Cl S by TOPREAL6:83
    .= proj1.:S by PRE_TOPC:22;
  hence thesis;
end;
