reserve T for non empty RelStr,
  A,B for Subset of T,
  x,x2,y,z for Element of T;

theorem Th40:
  Fdfl(A,1) = A^d
proof
  (Fdfl A).0=A & for B being Subset of T st B=(Fdfl A).0 holds (Fdfl(A)).(
  0+1) =B^d by Def8;
  hence thesis;
end;
