COLOQUIO DE MATEMÁTICAS 2020-I
ENTRADA LIBRE
Organizadores: Dario García
 
Se ofrecerá café, aromática y galletas después de las 5.00 p.m. al lado del salón del Coloquio.
Coloquios
anteriores:
Jueves 30 de Enero de 2020
B-402
4.00 p.m.
Federico Ardila - San Francisco State University
La geometría de las matroides

- Resumen


La teoría de matroides es una teoría combinatoria de la independencia, que tiene sus orígenes en el álgebra lineal y la teoría de grafos, y que resulta tener conexiones importantes con muchas otras áreas. Con el tiempo, las raíces geométricas de esta teoría se han hecho bastante más profundas, dando muchos frutos nuevos.

Recientemente, el acercamiento geométrico a la teoría de matroides ha llevado al desarrollo de matemática fascinante en la intersección de la combinatoria, el álgebra, y la geometría, y a la solucion de varias conjeturas clásicas. Esta charla resumirá algunos logros recientes.

Invitado por:

Darío Alejandro García
Jueves 13 de Febrero de 2020
B-402
4.00 p.m.
Jarod Alper - University of Washington
Advances in Moduli

- Resumen


Moduli spaces are fascinating spaces that appear in various guises across mathematics. Vaguely, a moduli space is a space (e.g. topological space, manifold or algebraic variety) whose points are in bijective correspondence with isomorphism classes of certain topological, geometric or algebraic objects (e.g. curves or vector bundles). We will provide an introduction to moduli spaces that appear in algebraic geometry with an emphasis on examples. We will see that the properties of a moduli space depend crucially on properties of the automorphism groups of the objects. We will first explain how one can construct a moduli space as a projective variety in the case when the automorphism groups are finite. Our final goal is to show how recent breakthroughs in the foundations of moduli theory allow for similar constructions even when the automorphism groups are not finite.

Invitado por:

Darío Alejandro García
Jueves 20 de Febrero de 2020
B-402
4.00 p.m.
Elio Espejo - University of Nottingham Ningbo China
A simultaneous blow-up problem arising in tumor modeling

- Resumen


Although macrophages are part of the human immune system, it has been remarkably observed in laboratory experiments that decreasing its number can slow down the tumor progression. We analyze through a recently mathematical model proposed inthe literature, necessary conditions for aggregation of tumor cells and macrophages. In order to do so, we prove the possibility of having blow-up in finite time. Next, we study if the aggregation of macrophages can occur when having a low density of tumor cells, and vice versa. With this purpose, we consider the problem of analyzing the existence or not of a simultaneous blow-up. We achieve this goal thanks to a novel process that allows us to compare the entropy functional associated with the density of each population, which turns out to be also a method to find enough conditions for having a simultaneous blow-up.

Invitado por:

Darío Alejandro García
Jueves 27 de Febrero de 2020
B-402
4.00 p.m.
Johannes Rau - Universidad de los Andes
TROPICAL GEOMETRY AND TROPICAL CURVE COUNTS

- Resumen


Tropical geometry is a combinatorial approach to classical algebraic geometry based on degeneration techniques. In my talk I want to present some of the basics of the subject and present some applications in enumerative geometry. I plan to present the computation of Gromov-Witten invariants (complex curve counts), Welschinger invariants (real invariants) up to new polynomial invariants which are still to be fully understood .

Invitado por:

Darío Alejandro García
Jueves 05 de Marzo de 2020
B-402
4.00 p.m.
Agnés Lagnoux - Université Tolouse Jean Jaurès
Sensitivity analysis: from variance analysis to Cramer-von Mises statistics

- Resumen


A classical problem in the study of computer code experiments is the evaluation of the relative influence of the input variables on some numerical result obtained by a computer code. In this context, the output is seen as a function f of random inputs (generally assumed independent) and a sensitivity analysis is performed using the so-called Hoeffding decomposition. In this functional decomposition, f is expanded as an L²-sum of uncorrelated functions involving only a part of the random inputs. This leads to the Sobol index that measures the amount of randomness (the part of the variance) of the output due to one or more input variables. It remains then to estimate these Sobol indices to rank the variables with respect to their influence on the output. Nevertheless, the Sobol indices and their Monte-Carlo estimation are order two methods: thus they are well adapted to measure the contribution of an input on the deviation around the output mean and it seems very intuitive that the sensitivity of an extreme quantile of the output could depend on sets of variables that cannot be captured using only the variances. One may generalize them with higher order methods. Indices based on contrast functions depending on the quantity of interest is a nice alternative when one considers quantiles or medians. Another promising possibility consists in defining indices depending on the whole distribution of the output conditioned by the input whose influence must be quantified.

Invitado por:

Darío Alejandro García
Jueves 12 de Marzo de 2020
B-402
4.00 p.m.
Juan Camilo Arias - Universidad de los Andes
Representaciones irreducibles y cómo encontrarlas.

- Resumen


Uno de los problemas fundamentales en teoría de representaciones es entender cómo una representación se puede escribir en términos de sus componentes irreducibles. Esta no es una tarea fácil, y aunque en principio es un problema puramente algebraico, su solución involucra una mezcla de técnicas tanto algebraicas como geométricas. En esta charla se mostrará cómo atacar este problema en diferentes categorías de representaciones, pasando desde grupos finitos hasta grupos cuánticos.

Invitado por:

Darío Alejandro García
Jueves 26 de Marzo de 2020
B-402
4.00 p.m.
Camilo Rengifo - Universidad de la Sabana
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- Resumen


Invitado por:

Darío Alejandro García
Jueves 02 de Abril de 2020
B-402
4.00 p.m.
Alexander Berenstein - Universidad de los Andes
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- Resumen


Invitado por:

Darío Alejandro García
Jueves 16 de Abril de 2020
B-402
4.00 p.m.
Marcos Escobar-Anel - Department of Statistical and Actuarial Sciences - University of Toronto
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Invitado por:

Darío Alejandro García
Jueves 23 de Abril de 2020
B-402
4.00 p.m.
Carolina Benedetti - Universidad de los Andes
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- Resumen


Invitado por:

Darío Alejandro García
Jueves 30 de Abril de 2020
B-402
4.00 p.m.
Michael Hoegele - Universidad de los Andes
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- Resumen


Invitado por:

Darío Alejandro García
Jueves 07 de Mayo de 2020
B-402
4.00 p.m.
Adolfo Quiroz - Universidad de los Andes
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- Resumen


Invitado por:

Darío Alejandro García
Jueves 14 de Mayo de 2020
B-402
4.00 p.m.
Jean Carlos Cortissoz - Universidad de los Andes
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- Resumen


Invitado por:

Darío Alejandro García