Stochastic OL Systems and Formal Power Series

It is a common problem in the study of stochastic grammars and languages and, in particular, of stochastic L systems that seemingly very little can be said about the probabilities of the word structures derived; in fact, most of the results obtained so far in these areas deal with word lengths and Parikh vectors rather than with the words themselves. Thus the stochastic generating process of the language is hardly reflected by the typical results.