  Infinite random sequences of letters can be viewed as stochastic chains or as
strings produced by a source, in the sense of information theory. The
relationship between Variable Length Markov Chains (VLMC) and probabilistic
dynamical sources is studied. We establish a probabilistic frame for context
trees and VLMC and we prove that any VLMC is a dynamical source for which we
explicitly build the mapping. On two examples, the ``comb'' and the ``bamboo
blossom'', we find a necessary and sufficient condition for the existence and
the unicity of a stationary probability measure for the VLMC. These two
examples are detailed in order to provide the associated Dirichlet series as
well as the generating functions of word occurrences.
