Context tree selection and linguistic rhythm retrieval from written texts

Publications | May 29, 2020

Antonio Galves, Charlotte Galves, Jesús E. García, Nancy L. Garcia, Florencia Leonardi

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. To carry on this approach, we compare texts from European and Brazilian Portuguese. These texts are previously encoded according to some basic rhythmic features of the sentences which can be automatically retrieved. This is an entirely new approach from the linguistic point of view. Our statistical contribution is the introduction of the smallest maximizer criterion which is a constant free procedure for model selection. As a by-product, this provides a solution for the problem of optimal choice of the penalty constant when using the BIC to select a variable length Markov chain. Besides proving the consistency of the smallest maximizer criterion when the sample size diverges, we also make a simulation study comparing our approach with both the standard BIC selection and the Peres-Shields order estimation. Applied to the linguistic sample constituted for our case study, the smallest maximizer criterion assigns different context-tree models to the two dialects of Portuguese. The features of the selected models are compatible with current conjectures discussed in the linguistic literature.

Limit theorems for chains with unbounded variable length memory which satisfy Cramer condition

Publications | May 15, 2020

Artem Logachov, A. Mogulskii and Anatoly Yambartsev

Here we obtain the exact asymptotics for large and moderate deviations, strong law of large numbers and central limit theorem for chains with unbounded variable length memory.

Neuromat Online Seminars

Events | Apr 20, 2020

The Research, Innovation and Dissemination Center for Neuromathematics (RIDC NeuroMat) will hold regular online team-wide seminars to present and discuss research progress. Guests and team members will be included in the program.

Neuromathematics research center holds six webinars on mathematics and neurobiology

News | Apr 20, 2020

This week, "Agência FAPESP" website featured an article about the RIDC NeuroMat series of online seminars on mathematics and neurobiology, NeuroMat/NeuroMod webinars 2020 - mathematics and neurobiology intertwined.

The webinars are part of a partnership with theInstitute for Modeling in Neuroscience and Cognition of Université Côte d'Azur (NeuroMod), France. The virtual meetings will take place every two weeks, from April 16 to June 25, 2020, via Google Meet at meet.google.com/xdz-rqup-dze.

NeuroMat/NeuroMod webinars 2020

Events, Newsletter | Apr 07, 2020

Amidst difficulties associated with the COVID-19 pandemics worldwide, in a context in which universities are closed and scientific missions are prohibited, we must do our best to keep scientific life alive. The series of webinars "Mathematics and Neurobiology Intertwined", presented on this page, bears the distinctive feature of bonding efforts and teams to move science forward.

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