Título: Random walk based algorithms for generating uniform spanning trees
Palestrante: Giulio Iacobelli (IM-UFRJ)
Data: 08/03/2021
Horário: 15h-16h
Local: Transmissão online
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Resumo: The task of efficiently generating uniform spanning trees of a graph has received much attention. A breakthrough came with Aldous-Broder and Wilson's algorithms, which can efficiently generate spanning trees based on random walks. In this work, we study the transient behavior of both algorithms. We introduce the notion of branches, which are paths generated by the two algorithms on particular stopping times. This interpretation is used to show a transient equivalence between the two algorithms on complete graphs. This equivalence yields a hybrid approach to generate uniform spanning trees of complete graphs faster than either of the two algorithms. We also propose a two-stage framework to explore this hybrid approach beyond complete graphs, showing its feasibility in some examples.
Título: Aprendizagem significativa de geometria no 8º ano do ensino fundamental: uma experiência além do material instrucional
Autor(a): Perla Christina Nunes da Silva
Defesa do Programa de Pós-Graduação em Ensino de Matemática (PEMAT/UFRJ).
Data: 04/03/2021
Horário: 15:00h
Local: Transmissão online
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Orientadora: Lilian Nasser
Título: Entropy Theory of Expansive Systems.
Autor: Elias Ferraz Rego
Data: 01/03/2021
Horário: 13:00h
Local: Transmissão Online
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Orientador: Alexander Arbieto
Coorientador: Alfonso Artigue
Banca Examinadora:
Alexander Arbieto - IM-UFRJ
Alfonso Artigue - UDELAR/Uruguai
Maria José Pacífico - IM-UFRJ
Jaqueline Siqueira - IM-UFRJ
Daniel Smania Brandão - ICMC-USP
Dante Carrasco Oliveira - U. Bio-Bio/Chile
Welington Cordeiro Nicolaus Copernicus - Univ./Polônia
Isaia Nisoli - IM-UFRJ (suplente)
Título: Cutoff and mixing times for exclusion processes with open boundaries
Palestrante: Nina Gantert, Technical University of Munich
Data: 02/03/2021
Horário: 13:30h
Local: Transmissão online
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Resumo: We study mixing times of the symmetric and asymmetric simple exclusion process on the segment where particles are allowed to enter and exit at the endpoints. We consider different regimes depending on the entering and exiting rates as well as on the rates in the bulk, and show that the process exhibits pre-cutoff and in some cases cutoff. Our main contribution is to study mixing times for the asymmetric simple exclusion process with open boundaries. We show that the order of the mixing time can be linear or exponential in the size of the segment depending on the choice of the boundary parameters, proving a striking different (and richer) behavior for the simple exclusion process with open boundaries than to the closed segment. In our arguments, we combine coupling, second class particle and censoring techniques together with current estimates. A novel idea is the use of special multi-species particle arguments, where the particles only obey a partial ordering. The talk is based on joint work with Evita Nestoridi (Princeton) and Dominik Schmid (Munich).
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ID da reunião: 958 0581 3232
Título: O ensino e a pesquisa em matemática no Rio de Janeiro em meados do século XX, um estudo de caso: a partir da trajetória acadêmica de Carlos Alberto Aragão de Carvalho (1924 – 1982)
Autor: Raphael Alcaires de Carvalho
Data: 26/02/2021
Horario: 14:00h
Local: Transmissão online
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Orientador: Antonio Augusto Passos Videira
Coorientadora: Tatiana Marins Roque
Evento da PEMAT/UFRJ - Programa de Pós-Graduação em Ensino de Matemática
