STATISTICS SEMINARS @ COLLEGIO CARLO ALBERTO Venerdì 29 Novembre 2019, alle ore 12:00, presso il nuovo edificio del Collegio Carlo Alberto, in Piazza Arbarello 8, Torino, si terrà il seguente seminario: ------------------------------------------------ Robin RYDER (Université Paris Dauphine) A BAYESIAN NON-PARAMETRIC METHODOLOGY FOR INFERRING GRAMMAR COMPLEXITY Based on a set of strings from a language, we wish to infer the complexity of the underlying grammar. To this end, we develop a methodology to choose between two classes of formal grammars in the Chomsky hierarchy: simple regular grammars and more complex context-free grammars. To do so, we introduce a probabilistic context-free grammar model in the form of a Hierarchical Dirichlet Process over rules expressed in Greibach Normal Form. In comparison to other representations, this has the advantage of nesting the regular class within the context-free class. We consider model comparison both by exploiting this nesting, and with Bayes’ factors. The model is fit using a Sequential Monte Carlo method, implemented in the Birch probabilistic programming language. We apply this methodology to data collected from primates, for which the complexity of the grammar is a key question. (joint work with L. Murray, J. Rousseau and A. Thin) ------------------------------------------------ Tutti gli interessati sono invitati a partecipare. Il seminario è organizzato dalla "de Castro" Statistics Initiative (www.carloalberto.org/stats <http://www.carloalberto.org/stats>) in collaborazione con il Collegio Carlo Alberto. Cordiali saluti, Pierpaolo De Blasi --- University of Torino & Collegio Carlo Alberto https://sites.google.com/a/carloalberto.org/pdeblasi/ <https://sites.google.com/a/carloalberto.org/pdeblasi/>