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Seminar on Applied and Computational Mathematics
Seminar on Applied and Computational Mathematics
19 de February de 2019, 14:00h 14:00 – 15:30
Room 232, IMPA2Classroom 232 (50) [Projector]
Title: The SwiftHohenberg Equation under directionalquenching: finding heteroclinic connections using spatial and spectral decompositions
Speaker: Rafael Monteiro – Mathematics for Advanced Materials – Open Innovation Laboratory (Japan)
Abstract: In this talk I will discuss the existence of patterns (nontrivial, stationary solutions) for onedimensional SwiftHohenberg Equation in a directional quenching scenario, that is, on $x\\leq 0$ the energy potential associated to the equation is bistable, whereas on $x\\geq 0$ it is monostable. This heterogeneity in the medium induces a symmetry break that makes the existence of heteroclinic orbits of the type pointtoperiodic not only plausible but, as we shall see, true. In this search we use interesting results of a memoir by Fefferman, LeeThorp, and Weinstein (''Topologically protected states in onedimensional systems" – American Mathematical Society, 2017) to understand the multiscale structure of the problem, namely, how fast/slow scales interact with each other. In passing, we advocate for a new approach in finding connecting orbits, using what we call “far/near decompositions'', relying on information about the asymptotic spatial behavior of the solutions, on spectral and harmonic analysis. Our method is functional analytic and PDE based, relying minimally on dynamical system techniques and making no use of comparison principles whatsoever. Joint work with N. Yoshinaga (Advanced Institute for Materials Research – Tohoku University).
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Seminar on Mathematical Methods in Finance
Seminar on Mathematical Methods in Finance
19 de February de 2019, 18:00h 18:00 – 19:30
Room 232, IMPA2Classroom 232 (50) [Projector]
Title: Can Gaussian factor models of commodity prices capture the financialization phenomenon?
Speaker: Fernando Aiube – UERJ
Abstract: In this presentation we investigate whether the Gaussian factor models can capture the financilization of commodity markets. The use of convenience yield as a stochastic factor is a common practice in the literature. This variable reflects the behavior of producers and physical traders. On the other hand, the great presence of equity traders during the financialization period could make the convenience yield factor less relevant for modeling the term structure of future prices. We find that the inclusion of the convenience yield as a second factor during the financialization improves the fit to empirical data. Hence, in the class of Gaussian factor models the convenience yield has a prominent role even in the financialization context.
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Seminar on Computer Graphics
Seminar on Computer Graphics
20 de February de 2019, 13:30h 13:30 – 15:00
Auditorium 3, IMPA2Auditorium 3 (100) [Live Recording & Streaming, Microphone, Projector]
Title: VR Kino+Theater
Speaker: Luiz Velho – IMPA
Abstract: The VR Kino+Theater platform integrates traditional forms of entertainment (theater and cinema), with advanced interactive media, (virtual reality and gaming). In this way, it solves the scalability of audience and presentation familiarity, while providing greater flexibility for innovative alternative formats.
The operation of such ecosystem entails new roles for producers, performers and participants.
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Seminar on Computer Graphics
Seminar on Computer Graphics
20 de February de 2019, 13:30h 13:30 – 15:00
Auditorium 3
Title: The many faces of stiffness
Speaker: Uri Ascher – Department of Computer Science, University of BC
Abstract: The words "stiff'', "stiffness'', "stiffening", etc., arise often in applications when simulating, calibrating and controlling dynamics. But these words often have different meanings in different contexts.A subset on which we will concentrate includes: Textbooktype (decaying) numerical ODE stiffness Highly oscillatory stiffness Stiffness matrix Numerical stiffening
Some of these terms are popular in scientific computing, while others come from mechanical engineering. A potential confusion may arise in this way, and it gets serious when more than one meaning is encountered in the context of one application. Such is the case with the simulation of deformable objects in visual computing, where all of the above appear in one way or another under one roof.
In this lecture I will describe the meaning of stiffness in each of these topics, how they arise, how they are related, what practical challenges they bring up, and how these challenges are handled in context. The concepts and their evolution will be demonstrated.
It is about meshes — their resolution and spectral properties — both in time and in space.
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Seminar on Probability and Combinatorics
Seminar on Probability and Combinatorics
20 de February de 2019, 15:30h 15:30 – 17:00
Room 349, IMPA3Classroom 349 (40)
Title: The K\”onig Graph Process
Speaker: Natasha Morrison – Cambridge and IMPA
Abstract: Say that a graph $G$ has property $\\mathcal{K}$ if the size of itsmaximum matching is equal to the order of a minimal vertex cover. Westudy the following process. Set $N:= \\binom{n}{2}$ and let $e_1, e_2,\\dots e_{N}$ be a uniformly random ordering of the edges of $K_n$, with$n$ an even integer. Let $\\Gour{0}$ be the empty graph on $n$ vertices.For $m \\geq 0$, $\\Gour{m+1}$ is obtained from $\\Gour{m}$ by adding theedge $e_{m+1}$ exactly if $\\Gour{m} \\cup \\{ e_{m+1}\\}$ has property$\\mathcal{K}$. We analyse the behaviour of this process, focusing mainlyon two questions: What can be said about the structure of $\\Gour{N}$ andfor which $m$ will $\\Gour{m}$ contain a perfect matching? This is jointwork with Nina Kamcev, Michael Krivelevich and Benny Sudakov.
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Seminar on Algebra
Seminar on Algebra
20 de February de 2019, 15:30h 15:30 – 17:00
Room 228, IMPA2Classroom 228 (50) [Projector]
Title: A Survey on simple derivations and their isotropy group
Speaker: Daniel Levcovitz – ICMCUSP
Abstract: We will present a survey on recent results on simple derivations of polynomial rings and their isotropy groups.
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Seminar on Computer Graphics
Seminar on Computer Graphics
22 de February de 2019, 13:30h 13:30 – 15:00
Auditorium 3, IMPA2Auditorium 3 (100) [Live Recording & Streaming, Microphone, Projector]
Title: CodeAssisted Music Composition with Python and Logic Pro X
Speaker: Marcelo Cicconet – Harvard University
Abstract: In this talk I will present experiments on how to integrate the power and flexibility of a general purpose programming language (Python, running on Jupyter) with the stability and extensive sound and effects library of a modern digital audio workstation (Logic Pro X) to compose an electronic dance music track. I will introduce and use simple music theory concepts to generate chord progression, bass line, arpeggios and other musical elements, which will be recorded in Logic via MIDI, using Logic's MIDI Clock messages for synchronization. The main advantage of using Python is the fact that it is popular and generalpurpose — there's no need to learn a specific musicrelated programming language. The main advantage of sending algorithmicallygenerated music to Logic is that this environment holds a comprehensive library of sounds and effects that allow fully producing a music piece into a professionalsounding track. I will present one such track, composed specially for this talk using some of the algorithms to be discussed.
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Seminar on Computer Graphics
Seminar on Computer Graphics
27 de February de 2019, 13:30h 13:30 – 15:00
Auditorium 3, IMPA2Auditorium 3 (100) [Live Recording & Streaming, Microphone, Projector]
Title: VR Tour
Speaker: Luiz Velho – IMPA
Abstract: VR Tour is a technological platform for the exploration of content in virtual reality. We present the core concepts of our platform followed by the conceptual and technical infrastructure which enables it. Then, we detail the elements involved in VR Tour
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Seminar on Computer Graphics
Seminar on Computer Graphics
27 de February de 2019, 13:30h 13:30 – 15:00
Auditorium 3
Title: VR Kino+Theater : The Tempest
Speaker: Luiz Velho – IMPA
Abstract: We present VR Kino+Theater, a platform that integrates traditional forms of entertainment (theater and cinema), with advanced interactive media, (virtual reality and gaming).
The foundations of our plataform lies onto three pillars related to technology, production, and delivery aspects which are the directions for the future media. The operation of such ecosystem entails new roles for producers, performers and participants.
We also show "The Tempest", an experiment based on the Shakespeare’s play that was produced as a proofofconcept of the VR Kino+Theater platform.
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Seminar on Probability and Combinatorics
Seminar on Probability and Combinatorics
27 de February de 2019, 15:30h 15:30 – 17:00
Room 349, IMPA3Classroom 349 (40)
Title: Probability in Number theory : Erdös Covering Systems
Speaker: Julian Sahasrabudhe – Cambridge and IMPA
Abstract: If $A_1,\\ldots,A_n$ are arithmetic progressions $A_i = d_i\\Z + a_i$, we say that $A_1,\\ldots,A_n$form a \\emph{covering system} if $\\bigcup_i^n A_i = \\mathbb Z$. Since their introduction in 1950 by Erdös, the subjectof covering systems has given rise to several attractive results and conjectures.For example, Hough proved (and thereby resolving a longstanding conjecture of Erdös) that one cannot coverthe integers with arithmetic progressions $A_1,\\ldots,A_n$ with \\emph{distinct} differences $d_1< \\cdots <d_n$ if the smallest difference is $> 10^{16}$.In this talk, I will discuss the resolution of some further conjectures on covering systems.This is joint work with Paul Balister, Béla Bollobás, Rob Morris and Marius Tiba.
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Seminar on Computer Graphics
Seminar on Computer Graphics
27 de February de 2019, 18:00h 18:00 – 19:30
Auditorium 3, IMPA2Auditorium 3 (100) [Live Recording & Streaming, Microphone, Projector]
Title: VR Tour : After The Tempest
Speaker: Luiz Velho – IMPA
Abstract: VR Tour is a technological platform for the exploration of content in virtual reality. We present the core concepts of our platform followed by the conceptual and technical infrastructure which enables it.
We also show "After The Tempest", a live performance of a new media experiment demonstrating our latest research in this area.
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