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

theorem
  Fdfl(A,2) = A^d^d
proof
  Fdfl(A,2)=Fdfl(A,1+1) .=(Fdfl(A,1))^d by Def8;
  hence thesis by Th40;
end;
