Título: "Oriented Percolation Models: Further improvement for the critical probability on regular trees"
Palestrante: Jaime Utria (IME-UFF)
Data: 10/04/2023
Horário: 15:30h
Local: C116 - Bloco C - CT – Instituto de Matemática – UFRJ.
Resumo: Let V be the vertex set of the regular tree of degree d + 1. We consider an oriented, dependent, and long-range bond percolation model. In this model, the underlying graph is the complete and oriented graph in which its vertex set is V. We derive a new upper bound for the critical probability of this model, and as a consequence, we retrieve and improve previous bounds for the critical probability of some particular models in the literature.
Todas as palestras são realizadas em Inglês.
Informações mais completas sobre os seminários estão disponíveis AQUI.
Título: "Noisy voters"
Palestrante: Rangel Baldasso (PUC-Rio)
Data: 27/03/2023
Horário: 15:30h
Local: C116 - Bloco C - CT – Instituto de Matemática – UFRJ.
Resumo: We study noise sensitivity of the consensus opinion of the voter model on finite graphs with respect to noise affecting the initial opinions and noise affecting the dynamics. We prove that the final opinion is stable with respect to small perturbations of the initial configuration and is sensitive to perturbations of the dynamics governing the evolution of the process. This talk is based on a joint work with G. Amir, O. Angel, and R. Peretz.
Todas as palestras são realizadas em Inglês.
Informações mais completas sobre os seminários estão disponíveis AQUI.
Título: Cliques quase-maximais em grafos aleatórios
Data: 09/01/2023, às 15:30h
Local: CT - Instituto de Matemática/UFRJ, Bloco B - sala B106-A
Palestrante: Simon Griffiths (PUC/RJ)
Resumo: Consideramos a questão de quantos cliques quase-maximais disjuntos podem ser encontrados num grafo aleatório G(n,p). Em 1992, Alon e Spencer conjecturaram que existe uma família de ordem n^2/(log n)^2 tais cliques disjuntos. Recentemente Acan e Kahn mostraram que a conjectura é falsa, provando uma cota superior da forma O(n^2/(log n)^3). Nós fornecemos uma cota inferior da mesma ordem.
Informações sobre todo o programa dos seminários de probabilidade clique AQUI
Título: Quantitative results in Poincaré recurrence for mixing processes
Palestrante: Alexsandro Gallo (UFSCar)
Data: 16/01/2023
Horário: 15:00h
Local: Transmissão Online
Confira AQUI o link para a transmissão.
Resumo: A very classical question in stochastic processes is to quantify the time it takes to first enter a given set, or the number of visits to this set in a fixed time window. The aim of the talk is to present some recent quantitative results concerning first hitting/return times and number of visits to rare sets (small/vanishing measure) in mixing processes. We will focus on asymptotic results (essentially convergence in distribution and large deviations). Most of the presentation will be about the classical case where the sets of interest are strings of symbols of increasing size. At the end, if time allows, we will give some glimpses of the case in which we target general sets having vanishing measure.
All the talks are held in English.
More complete information about the seminars will be available at HERE.
Título: KPZ fluctuations of the Wick ordered planar stochastic heat equation
Palestrante: Alejandro Ramírez (PUC-Chile)
Data: 09/12/2022
Horário: 15:00h
Local: Transmissão online
Confira AQUI o link para a transmissão.
Resumo: We give a rigorous formulation of the Wick ordered stochastic heat equation, with planar white noise, whose solution is the free energy of an undirected random polymer, using a version of the Skorokhod integral. The solution is represented as an L^1 limit of a martingale given by the Feynman-Kac formula. We also show that the fundamental solution far from the center has fluctuations given by the 1+1 KPZ equation. This is a joint work with Jeremy Quastel and Balint Virag.
The talk will be held in English.
More complete information about the seminars will be available HERE.
