Anna Corazza Giorgio Satta Probabilistic Context-Free Grammars Estimated from Infinite Distributions. 1379-1393 2007 29 IEEE Trans. Pattern Anal. Mach. Intell. 8 http://doi.ieeecomputersociety.org/10.1109/TPAMI.2007.1065 db/journals/pami/pami29.html#CorazzaS07