reserve TS for 1-sorted,
  K, Q for Subset of TS;
reserve TS for TopSpace,
  GX for TopStruct,
  x for set,
  P, Q for Subset of TS,
  K , L for Subset of TS,
  R, S for Subset of GX,
  T, W for Subset of GX;

theorem Th39:
  Int T misses Fr T
proof
  Fr T = Cl T /\ (((Cl T`)`)`) .= Cl T \ ((Cl T`)`) by SUBSET_1:13;
  hence thesis by XBOOLE_1:79;
end;
