Probabilistic and weighted grammars

Devices for the generation of languages, corresponding to the probabilistic recognition devices or probabilistic automata, are introduced and the resulting families of languages are investigated. Comparisons are made with some other recently introduced grammars, where restrictions are imposed not only on the form of the rewriting rules but also on the use of them. A uniform representation for such grammars is provided by the notion of a grammar with a prescribed control language for the derivations