
theorem Th10:
  for m be non zero Element of NAT, Z be non empty Subset of REAL m,
      f be PartFunc of REAL m,REAL, i,j be Nat
        st f is_continuously_differentiable_up_to_order i,Z & j <= i
      holds f is_continuously_differentiable_up_to_order j,Z
 by PDIFF_9:84,XXREAL_0:2;
