reserve X for non empty set,
  Y for set,
  S for SigmaField of X,
  M for sigma_Measure of S,
  f,g for PartFunc of X,COMPLEX,
  r for Real,
  k for Real,
  n for Nat,
  E for Element of S;

theorem
  for X be non empty set, f being Functional_Sequence of X,REAL, n
  being Nat holds (R_EAL f)^\n = R_EAL(f^\n);
