  We describe general approach to classification of character sequences (texts,
DNA) using relative entropy estimated by off-the-shelf compression and Markov
Chains and find them precise enough.
  We also notice that the method for estimating relative entropy described in
the paper cond-mat/0108530 "Language Trees..." by D. Benedetto et al. was
considered earlier and was found to be easily surpassed by the simple and
computationally effective first order Markov Chain approach.
