{"id":306,"date":"2024-09-18T19:05:18","date_gmt":"2024-09-18T19:05:18","guid":{"rendered":"http:\/\/localhost:8000\/?page_id=306"},"modified":"2024-09-18T19:34:55","modified_gmt":"2024-09-18T19:34:55","slug":"seminarios-de-probabilidade-2016","status":"publish","type":"page","link":"https:\/\/ppge.im.ufrj.br\/en\/seminarios-de-probabilidade-2016\/","title":{"rendered":"Semin\u00e1rios de probabilidade \u2013 2016"},"content":{"rendered":"

Semin\u00e1rios de probabilidade \u2013 2016<\/h2><\/div>
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Coordena\u00e7\u00e3o:\u00a0<\/strong>Professora Maria Eulalia Vares<\/p>\n

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As palestras ocorrerem na sala C-119 nas segundas-feiras as 15h30, a menos de algumas exce\u00e7\u00f5es devidamente indicadas.<\/p>\n<\/div>\n<\/div>\n<\/div>

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Lista completa<\/strong><\/p>\n<\/div>

<\/i><\/i><\/span>05\/12
\nCasamento de grafos: modelos, viabilidade e desempenho de algoritmos<\/em>
\nJefferson Elbert Sim\u00f5es (COPPE-UFRJ)<\/span><\/a><\/h4><\/div>
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O problema de casamento de grafos surge naturalmente em contextos como privacidade em redes sociais, bioinform\u00e1tica e vis\u00e3o computacional. O objetivo geral deste problema \u00e9 encontrar uma correspond\u00eancia oculta entre v\u00e9rtices de dois grafos G_1 e G_2, cujas estruturas s\u00e3o correlacionadas. Diversos trabalhos foram bem-sucedidos em trabalhar este problema por um vi\u00e9s mais aplicado, mas apenas recentemente foram propostas abordagens te\u00f3ricas para a compreens\u00e3o de seus limites fundamentais. Nesta palestra, irei apresentar um panorama geral sobre o estado da arte em casamento de grafos por um vi\u00e9s te\u00f3rico, incluindo alguns modelos para grafos aleat\u00f3rios correlacionados recentemente propostos. Para um modelo em particular, o modelo G(n,p,s), irei demonstrar que casar grafos \u00e9 vi\u00e1vel mesmo sob condi\u00e7\u00f5es modestas para o grau m\u00e9dio destes grafos, e apresentar garantias de desempenho para algoritmos baseados em heur\u00edsticas. Por fim, irei brevemente discutir uma generaliza\u00e7\u00e3o deste problema para m\u00faltiplos grafos de entrada.<\/div>\n
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Refer\u00eancias principais:\u00a0<\/strong>
\nPedarsani, P. and Grossglauser, M., 2011, August. On the privacy of anonymized networks. In Proceedings of the 17th ACM SIGKDD international conference on
\nKnowledge discovery and data mining (pp. 1235-1243). ACM.
\nYartseva, L. and Grossglauser, M., 2013, October. On the performance of percolation graph matching. In Proceedings of the first ACM conference on
\nOnline social networks (pp. 119-130). ACM.
\nChiasserini, C.F., Garetto, M. and Leonardi, E., 2015, April. De-anonymizing scale-free social networks by percolation graph matching. In 2015 IEEE Conference on Computer Communications (INFOCOM) (pp. 1571-1579). IEEE.
\nSimoes, J.E., 2016. Two Problems on the Structure-Identity Relationship on Networks (Doctoral dissertation, Universidade Federal do Rio de Janeiro).<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div><\/div><\/div>

<\/i><\/i><\/span>07\/11
\nTopics in ballistic and transient conditions for RWRE<\/em>
\nEnrique Guerra Aguilar (PUC - Chile)<\/span><\/a><\/h4><\/div>
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In this talk, I will present my two results within the framework of random walks in random environments. The first one is related to Sznitman Ballisticity conditions for RW in uniform elliptic i.i.d. random environments. For this kind of environments we prove an almost exponential decay for the condition (T\u2019) (EJP 2015). The second result is for RW in strong mixing random environments, a strictly larger class of environments. Here, we prove the existence of an asymptotic direction under a sort of polynomial \u201dballisticity\u201d condition and we will try to explain possible issues to prove asymptotics laws in this model. The results are joint work with Alejandro Ramirez.<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div><\/div><\/div>

<\/i><\/i><\/span>04\/11
\nNonlocal Conservation laws from Stochastic Particle Systems (In coraboration with Marielle Simon(Inria, France)<\/em>
\nChristian Olivera (Unicamp)<\/span><\/a><\/h4><\/div>
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We consider an interacting particle system modeled as a system of $N$ stochastic differential equations driven by Levy process. The limiting behavior as the size $N$ grows to infinity is achieved as a law of large numbers for the empirical process associated with the interacting particle system.<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div><\/div><\/div>

<\/i><\/i><\/span>14\/10
\nPropaga\u00e7\u00e3o de chamas em canais de Hele-Shaw: uma abordagem estat\u00edstica da hidrodin\u00e2mica<\/em>
\nDomingos H. Marchetti (IF-USP)<\/span><\/a><\/h4><\/div>
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Apresentaremos neste semin\u00e1rio alguns poucos resultados e tentativas de uma <\/span><\/a>investiga\u00e7\u00e3o estat\u00edstica da hidrodin\u00e2mica de uma g\u00e1s em expans\u00e3o t\u00e9rmica devido sua combust\u00e3o, como sugerida por Onsager em seu trabalho seminal sobre turbul\u00eancia, visando interpretar o experimento realizado por Paul D. Ronney em chamas pr\u00e9-misturadas (combust\u00edvel e oxidante) se propagando em canais de Hele-Shaw.<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div><\/div><\/div>

<\/i><\/i><\/span>10\/10
\nScaling limit for the random hopping dynamics for the 2-level GREM at low temperature\/em>
\nLuiz Renato Fontes (IME-USP)<\/span><\/a><\/h4><\/div>
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We discuss the scaling limit for the random hopping dynamics for the 2-level <\/span><\/a>GREM at low temperature and ergodic time scales (right before reaching equilibrium). We have results for the cascading phase (where the equilibrium distribution concentrates on cascades of minima of the associated energies at each level). Depending on the temperature, we may get a 1-level weighted K process, a 2-level K process, or a combination of K-process on the first level, and equilibrium on the second level.<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div><\/div><\/div>

<\/i><\/i><\/span>05\/09
\nGradient flow technicques n PDEs and stochastic evolutions<\/em>
\nMauro Mariani (Universit\u00e0 di Roma \u201cLa Sapienza\u201d)<\/span><\/a><\/h4><\/div>
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I will discuss some applications of gradient flow techniques to recover singular limits of rather well known dynamics. In particular I will focus on backward-forward parabolic equations and some metastable description of diffusion processes. I will present classical and recent results, as well as open problems.<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div><\/div><\/div>

<\/i><\/i><\/span>01\/07
\nGeneralized Smoluchowski Equations and Scalar Conservation Laws<\/em>
\nFraydoun Rezakhanlou (U.C. Berkeley)<\/span><\/a><\/h4><\/div>
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By a classical result of Bertoin, if initially a solution to Burgers\u2019 equation is a Levy process without positive jumps, then this property persists at later times.<\/div>\n
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According to a theorem of Groeneboom, a white noise initial data also leads to a Levy process at positive times. Menon and Srinivasan observed that in both
\naforementioned results the evolving Levy measure satisfies a Smoluchowski-type equation. They also conjectured that a similar phenomenon would occur if
\ninstead of Burgers\u2019 equation, we solve a general scalar conservation law with a convex flux function. Though a Levy process may evolve to a Markov process
\nthat in most cases is not Levy. The corresponding jump kernel would satisfy a generalized Smoluchowski equation. Along with Dave Kaspar, we show that a
\nvariant of this conjecture is true for monotone solutions to scalar conservation laws.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div><\/div><\/div>

<\/i><\/i><\/span>16\/05
\nA fase cr\u00edtica da percola\u00e7\u00e3o orientada no plano<\/em>
\nAugusto Q. Teixeira (IMPA)<\/span><\/a><\/h4><\/div>
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Nessa palestra falaremos sobre o modelo de percola\u00e7\u00e3o orientada. Esse modelo <\/span><\/a>j\u00e1 recebeu bastante aten\u00e7\u00e3o por sua simplicidade e sua estreita rela\u00e7\u00e3o com o processo de contato. Trabalhos muito interessantes sobre o assunto j\u00e1\u00a0 elucidaram bastante sobre as fases sub-cr\u00edtica e super-cr\u00edtica do modelo. Quanto \u00e0 fase cr\u00edtica, o resultado mais citado \u00e9 devido a Bezuidenhout e Grimmett, onde eles mostram que o processo n\u00e3o percola no ponto cr\u00edtico (para qualquer dimens\u00e3o). Nessa palestra falaremos de uma nova t\u00e9cnica que, apesar de funcionar apenas no plano, permite um estudo mais aprofundado do modelo no ponto cr\u00edtico. Daremos detalhes dos resultados e das ferramentas empregadas.<\/div>\n
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Essa palestra \u00e9 baseada em um trabalho em conjunto com H. Duminil-Copin e V. Tassion.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div><\/div><\/div>

<\/i><\/i><\/span>11\/04
\nContinuum to discrete via double coin flips<\/em>
\nDaniel Ahlberg (IMPA)<\/span><\/a><\/h4><\/div>
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Many complex systems involving many independent variables have come to be very <\/span><\/a>well understood. One such example is Bernoulli percolation on a planar lattice. However, closely related models, such as continuum percolation in $mathbb^2$, may require quite different techniques. We will describe some techniques of this kind that recently has been developed for Poisson Boolean percolation. We will focus on a certain two-stage construction that allows for a reduction to the discrete setting, where a larger arsenal of techniques may be applied to study phenomena such as sharp thresholds and noise sensitivity.<\/div>\n
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Joint work with Vincent Tassion and Augusto Teixeira.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div><\/div><\/div>

<\/i><\/i><\/span>04\/04
\nFrom reaction-diffusion models to the study of SDEs<\/em>
\nConrado Freitas P. da Costa (IMPA)<\/span><\/a><\/h4><\/div>
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N\u00e3o dispon\u00edvel.<\/p>\n

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<\/i><\/i><\/span>22\/02
\nWASEP with a slow bond: crossover to the KPZ equation<\/em>
\nTertuliano Franco (UFBA)<\/span><\/a><\/h4><\/div>
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We will start with an over-view on works related to the macroscopic effect of a slow bond in symmetrical (or weakly assymetrical) exclusion process. Then we will focus on our recent work concerned with fluctuations of the WASEP with a slow bond. Depending on the chosen parameters, the fluctuations of this model can be driven by: 1) an Ornstein-Uhlenbeck process governed by the heat equation; 2) an Ornstein-Uhlenbeck process governed by the heat equation with Neumann boundary conditions; 3) an Ornstein-Uhlenbeck process governed by the heat equation with some Robin boundary conditions; 4) an Ornstein-Uhlenbeck process governed by the heat equation with Robin boundary conditions and stronger noise; and last but not least, 5) the stochastic Burgers equation, corresponding to the KPZ (Kardar-Parisi-Zhang) regime. Based on joint work with P. Gon\u00e7alves and M. Simon.<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div><\/div><\/div>

<\/i><\/i><\/span>25\/01 (excepcionalmente na sala C-116)
\nHomeomorfismos com entropia zero no plano e na esfera<\/em>
\nFabio Armando Tal (IME-USP)<\/span><\/a><\/h4><\/div>
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Utilizamos uma teoria recente de forcing para mapas de superf\u00edcies no estudo dos homeomorfismos da esfera. Um resultado cl\u00e1ssico de Katok mostra que, para sistemas suficientemente suaves, se a entropia topol\u00f3gica for positiva sempre \u00e9 poss\u00edvel encontrar uma Ferradura din\u00e2mica. Entretanto, pouco \u00e9 conhecido das restri\u00e7\u00f5es de homeomorfismos com entropia zero. Nosso trabalho busca mostrar que, nestas situa\u00e7\u00f5es, a din\u00e2mica toda possui uma rigidez muito similar \u00e0 encontrada na din\u00e2mica de fluxos cont\u00ednuos. Entre outros resultados, mostraremos tamb\u00e9m que \u00e9 poss\u00edvel obter um resultado similar ao cl\u00e1ssico Teorema de Poincar\u00e9-Bendixson descrevendo o comportamento assint\u00f3tico de \u00f3rbitas. Mais especificamente, se f \u00e9 um homeomorfismo com entropia nula da esfera com ao menos 3 pontos peri\u00f3dicos ent\u00e3o, para todo ponto x, existe uma pot\u00eancia de f tal que omega limite da \u00f3rbita de x pertence a uma destas situa\u00e7\u00f5es:<\/div>\n
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1 \u2013 O omega-limite est\u00e1 contido num ciclo feito de pontos fixos e pontos heterocl\u00ednicos a eles.
\n2 \u2013 O omega-limite \u00e9 um conjunto rodando com velocidade irracional ao redor de um ponto fixo.
\n3 \u2013 O omega-limite \u00e9 um conjunto \u201cinfinitamente renormaliz\u00e1vel\u201d, onde a din\u00e2mica \u00e9 semi conjugada \u00e0 din\u00e2mica de um od\u00f4metro simb\u00f3lico.<\/p>\n

Tamb\u00e9m apresentaremos algumas consequ\u00eancias para diffeomorfismos dissipativos do plano (como os da Fam\u00edlia de H\u00e9non), mostrando que atratores transitivos nestas situa\u00e7\u00f5es s\u00f3 podem ser \u00f3rbitas peri\u00f3dicas.<\/p>\n

Trabalho conjunto com P. Le Calvez.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div><\/div><\/div><\/div><\/div><\/div><\/div><\/div><\/div>","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"open","template":"100-width.php","meta":{"footnotes":""},"class_list":["post-306","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/ppge.im.ufrj.br\/en\/wp-json\/wp\/v2\/pages\/306","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ppge.im.ufrj.br\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/ppge.im.ufrj.br\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/ppge.im.ufrj.br\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ppge.im.ufrj.br\/en\/wp-json\/wp\/v2\/comments?post=306"}],"version-history":[{"count":3,"href":"https:\/\/ppge.im.ufrj.br\/en\/wp-json\/wp\/v2\/pages\/306\/revisions"}],"predecessor-version":[{"id":309,"href":"https:\/\/ppge.im.ufrj.br\/en\/wp-json\/wp\/v2\/pages\/306\/revisions\/309"}],"wp:attachment":[{"href":"https:\/\/ppge.im.ufrj.br\/en\/wp-json\/wp\/v2\/media?parent=306"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}