Coloquio 18 de Mayo 2015

Enumerating maximum length chains in the Tamari lattice

Expositor:  Susanna Fishel

Institución: IMAFI

Lunes 18 de mayo a las 17:00 hrs.
Sala de magíster.

Resumen: Fifty or so years ago Tamari defined a lattice, now known by his name. It has Catalan number of vertices–its Hasse diagram, as an undirected graph, is the one-skeleton of the associahedron– and it is a quotient of the weak Bruhat order. Much is known about this remarkable lattice, but, as Knuth says, the number of maximal chains «remains mysterious.» This is especially odd, because the numbers of maximal chains in many closely related lattices are known. I will describe work with my student Luke Nelson on enumerating maximum length chains. We hope it is progress toward finding the number of maximal chains.

Coloquio 6 de Mayo 2015

Uniformly rational varieties and equivariant definitions

Expositor: Charlie Petitjean

Institución: Institut de Mathématiques de Bourgogne

Miércoles 6 de mayo a las 16:30 hrs.
Sala de magíster.

Resumen: A uniformly rational variety is a smooth algebraic variety for which every point has a Zariski open neighborhood isomorphic to an open subset of the affine space. A uniformly rational variety is in particular a smooth rational variety, however the converse is a conjecture. In this talk I will introduce a generalizations of this conjecture considering varieties with group actions.

Coloquio 21 de Abril de 2015

Modelando la realidad a través del Cálculo Fraccionario

Expositor: M. Pilar Velasco Cebrián.

Afiliación:
Centro Universitario de la Defensa de Zaragoza
Instituto Universitario de Matemáticas y Aplicaciones
Instituto de Matemática Interdisciplinar 

Martes 21 de abril a las 16:30 hrs.
Sala de magíster.

Coloquio 13 de Abril 2015

Rigidez en grupos de difeomorfismos del intervalo..

Expositor: Cristóbal Rivas. USACH, Chile

Lunes 13 de abril a las 16:00 hrs.
Sala de magíster.

Resumen: Revisaremos algunos resultados recientes (y otros no tanto) sobre rigidez para grupos finitamente generados de difeomorfismos del intervalo (compacto). Pondremos énfasis en grupos solubles y nilpotentes.

Coloquio 9 de abril 2015

Expositor: Prof. Fernando Rodriguez-Villegas. International Centre for Theoretical Physics, Trieste, Italy

Viernes 10 de abril a las 15:30 hrs.
Sala de magíster.

Coloquio 12 de Marzo 2015

Irreducible representations and decomposition matrices for rational Cherednik algebras

Expositor: Emily Norton. Kansas State University

Jueves 12 de marzo a las 16:00 hrs.
Sala de magíster.

Resumen: Rational Cherednik algebras H_c(W) have a representation theory that echoes that of semisimple complex Lie algebras, in that there is a highest weight category of «nice» representations, Category O, containing Verma modules which have unique simple quotients. In particular, all the simple representations belong to this category and they are indexed by the simple representations of the underlying complex reflection group W. The characters of simple representations can be found from the decomposition matrix, which encodes the multiplicities of simples in the composition series of Vermas. I will survey what is known for W a real reflection group, and how to explicitly find these decomposition matrices when W is one of the exceptional real reflection groups (type E, F, and H).