24/02/2020
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SIMBa: Elliptic PDE 1: Why do we study them?

El proper dimecres, 26 de febrer, se celebrarà una nova xerrada del Seminari Informal de Matemàtiques de Barcelona (SIMBa).

Speaker: Damià Torres
Universitat: Universitat de Barcelona.

Data: Wednesday, 26th of February
Hora: 12:00, coffee break (be eco friendly, bring your cup); 12:20, talk.
Lloc: B1 classroom, Facultat de Matemàtiques de la Universitat de Barcelona.
Idioma: English

Títol: Elliptic PDE 1: Why do we study them?
Resum: Elliptic PDE theory plays a central role in modern mathemati-cal analysis, and it is connected with probability and geometricmeasure theory. Historically, elliptic PDE come from physicalproblems related to the heat equation, first studied by Fourier in1822, and also from the Poisson equation, that appears in electro-magnetism. In this first talk, we discuss both classical and modernapplications, and we introduce concepts to state the main problemin the field: existence, uniqueness and regularity of solutions.

Si voleu estar al cas de les xerrades previstes, podeu consultar el calendari. Si voleu proposar una xerrada, ompliu el formulari. Si voleu contactar amb els responsables podeu escriure un missatge a seminari(dot)simba(at)ub(dot)edu.

10/02/2020
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SIMBa: An introduction to Floer theory

El proper dimecres, 12 de febrer, se celebrarà una nova xerrada del Seminari Informal de Matemàtiques de Barcelona (SIMBa).

Speaker: Joaquim Brugués
Universitat: Universitat Politècnica de Catalunya.

Data: Wednesday, 12th of February
Hora: 12:00, coffee break (be eco friendly, bring your cup); 12:20, talk.
Lloc: B1 classroom, Facultat de Matemàtiques de la Universitat de Barcelona.
Idioma: English

Títol: An introduction to Floer theory
Resum: The development of Floer theory is a history of collaboration andintersection of ideas that starts with a conjecture by Arnold in1966 on a Morse-like lower bound on the number of fixed points ofa symplectomorphism. The efforts to prove this conjecture (now atheorem) motivated the development of tools that are still essentialin symplectic topology investigation. In this talk we aim to presentthe conjecture and sumarize the history, ending with the definitionof Floer homology.

28/01/2020
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SIMBa: Morse theory: from dynamics to topology and back

El proper dimecres, 29 de gener, se celebrarà una nova xerrada del Seminari Informal de Matemàtiques de Barcelona (SIMBa).

Speaker: Joaquim Brugués
Universitat: Universitat Politècnica de Catalunya.

Data: Wednesday, 29th of January
Hora: 12:00, coffee break (be eco friendly, bring your cup); 12:20, talk.
Lloc: S1 classroom, Facultat de Matemàtiques de la Universitat de Barcelona.
Idioma: English

Títol: Morse theory: from dynamics to topology and back
Resum: Morse theory relates the critical points of a smooth function defi-ned on a manifold to the topology of the manifold, in a way thatallows to construct a homology equivalent to the singular homo-logy from classical algebraic topology. The main result from thisconstruction are the Morse inequalities, that give a lower boundon the number of critical points of a smooth function that dependssolely on the underlying topology. In this talk we will present theideas behind this construction and the most remarkable results ofthe theory. It’s recommended to have some previous knowledgeof differential geometry and/or algebraic topology to understandthis talk.

10/01/2020
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SIMBa: Learning the structure of graphical models by covariance queries

Actualització 14/1/20: Atenció, canvi d’aula! La xerrada se celebrarà a l’aula S1

El proper dimecres, 15 de gener, se celebrarà una nova xerrada del Seminari Informal de Matemàtiques de Barcelona (SIMBa).

Speaker: Vasiliki Velona
Universitat: Universitat Politècnica de Catalunya.

Data: Wednesday, 15th of January
Hora: 12:00,coffee break (be eco friendly, bring your cup); 12:20, talk.
Lloc: ~~B1 classroom~~, Facultat de Matemàtiques de la Universitat de Barcelona.
Idioma: English

Títol: Learning the structure of graphical models by covariance queries
Resum: I will talk about the problem of learning the zero-pattern of theinverse covariance matrix of a Gaussian distribution, in the high-dimensional setting. This is a problem with several applications,for instance inference of genetic networks. After giving a con-crete mathematical statement of the problem, I will discuss someefficient algorithms as well as lower bounds for their performance.

29/11/2019
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SIMBa: The philosophy of the $h$-principle

El proper dimecres, 4 de desembre, se celebrarà una nova xerrada del Seminari Informal de Matemàtiques de Barcelona (SIMBa).

Speaker: Robert Cardona Aguilar
Universitat: Universitat Politècnica de Catalunya

Data: Wednesday, 4th of December
Hora: 12:00, coffee break; 12:20, talk
Lloc: B1 classroom, Facultat de Matemàtiques de la Universitat de Barcelona.
Idioma: English

Títol: The philosophy of the $h$ -principle
Resum: The homotopy principle (or $h$ -principle) is a very general way tosolve partial differential equations and relations which frames ide-as of Smale and Nash. It is a far-reaching tool with applicationsin a lot of different topics as PDE’s, foliations, cobordisms, sym-plectic topology or Riemannian geometry. Gromov’s work was arevolution in geometry even if th $h$ -principle has been known as “the hardest part of Gromov’s work to popularize”. In this talk,we will present a very informal approach to these ideas and com-ment some of its applications. Time permiting, we will mentionshortly how it is used in a recent paper in the context of contacttopology, and prove a conjecture concerning the Euler equationsfor ideal fluids in Riemannian manifolds. This last part is a jointwork with E. Miranda, D. Peralta-Salas and F. Presas.

25/11/2019
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SIMBa: Postquantum cryptography: what, why, and how?

El proper dimecres, 27 de novembre, se celebrarà una nova xerrada del Seminari Informal de Matemàtiques de Barcelona (SIMBa).

Speaker: Enric Florit Zacarías
Universitat: Universitat de Barcelona

Data: Wednesday, 27th of November
Hora: 12:00, coffee break; 12:20, talk
Lloc: Aula B1 Facultat de Matemàtiques de la Universitat de Barcelona.
Idioma: English

Títol: Postquantum cryptography: what, why, and how?
Resum: The key agreement scheme proposed by Diffie and Hellman in 1976 relies on the problem of finding discrete logarithms. One can choose appropriate groups where the best algorithms for solving this problem are too slow, such as certain elliptic curves over finite fields. There are already proposed quantum algorithms that break discrete logarithms in polynomial time. For this reason multiple “post-quantum” cryptography primitives have appeared in the last years, while trying to find harder computational problems. One of the proposed protocols using elliptic curves is SIDH/SIKE, candidate to the NIST Post-Quantum Cryptography Competition.

10/06/2019
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SIMBa: Isogenies and Cryptography

El proper dimecres, 12 de juny, se celebrarà una nova xerrada del Seminari Informal de Matemàtiques de Barcelona (SIMBa).

Speaker: Coral Real Llamas
Universitat: Eurecat – Centre Tecnològic de Catalunya

Data: Dimecres, 12 de juny de 2019
Hora: 12:00, cafè; 12:20, xerrada
Lloc: Aula B1 Facultat de Matemàtiques de la Universitat de Barcelona.
Idioma: Castellà

Títol: Isogenies and Cryptography
Resum: Nowadays in post-quantum cryptography the use of isogenies isincreasing. They are used in key exchange or in signature sc-hemes. After a brief introduction to the concept of isogeny, inthis talk we explain how they are being used in quantum-resistantcryptography.