theorem Th19:
  for f,g being ext-real-valued FinSequence
  st f^g is with_values_greater_or_equal_one
  holds
  f is with_values_greater_or_equal_one &
  g is with_values_greater_or_equal_one
  proof
    let f,g being ext-real-valued FinSequence;
    rng f c= rng(f^g) & rng g c= rng(f^g) by FINSEQ_1:29,30;
    hence thesis;
  end;
