reserve FT for non empty RelStr;
reserve A for Subset of FT;
reserve T for non empty TopStruct;
reserve FMT for non empty FMT_Space_Str;
reserve x, y for Element of FMT;
reserve A, B, W, V for Subset of FMT;

theorem
  A^Fodelta = (A`)^Fodelta
proof
  A^Fodelta = (((A`)`)^Fob) /\ ((A`)^Fob) by Th39;
  hence thesis by Th39;
end;
