The starting point of this article is the question "How to retrieve
fingerprints of rhythm in written texts?". We address this problem in the case
of Brazilian and European Portuguese. These two dialects of Modern Portuguese
share the same lexicon and most of the sentences they produce are superficially
identical. Yet they are conjectured, on linguistic grounds, to implement
different rhythms. We show that this linguistic question can be formulated as a
problem of model selection in the class of variable length Markov chains.