Notiziario Scientifico

Settimana dall'8 al 14 luglio 2013


Lunedì 8 luglio 2013
Ore 9:30, Accademia Nazionale dei Lincei
Convegno "Mathematics and Quantum Physics"
9:30 Corrado De Concini, Welcome address
10:00 Victor Kac, Algebraic theory of integrable partial differential equations
11:00 Coffee break
11:30 Sorin Popa, A II_1 factor approach to the Kadison-Singer problem
14:00 Karl-Henning Rehren, Chiral quantum cloning
15:00 Coffee break
15:30 Simone Warzel, Spectral properties of the quantum random energy model
16:30 Yoh Tanimoto, Operator algebraic construction of two-dimensional quantum field models


Lunedì 8 luglio 2013
Ore 11:00, Aula G
Livia Corsi (Università di Napoli)
Un Teorema Nash-Moser astratto con applicazioni ai problemi di esistenza di soluzioni quasi-periodiche per PDE Hamiltoniane su varietà compatte, I
Questo è il primo di una serie di tre seminari in cui illustrerò un risultato ottenuto in collaborazione con M. Berti e M. Procesi sull'esistenza di soluzioni quasi-periodiche per l'equazione di Schrodinger non-lineare su gruppi di Lie compatti.


Lunedì 8 luglio 2013
Ore 15:00, Aula H
Seminario di Algebra e Geometria
Raffaele Vitolo (Università del Salento)
On differential-geometric properties of third-order homogeneous Dubrovin-Novikov Hamiltonian operators
Homogeneous differential-geometric Poisson brackets were introduced by Dubrovin and Novikov in 1984. Such operators appear in many integrable systems. First order operators have been extensively studied so far. We will present new results on the description and the classification of third order operators. If such operators are part of a bi-Hamiltonian formulation of a given system of PDEs, then the structure of the operator can be expressed in terms of a sequence of homogeneous conservation law densities in involution coming from the Magri scheme. This fact can be used in opposite direction to reconstruct the third-order operator and find new bi-Hamiltonian systems. On the other hand, third order operators may be described using their zero-degree Casimirs. In these coordinates the operators are completely described from their leading term (if this term is a non-degenerate metric). We provide a complete classification for a number of field variables equal to 3, and provide a general method for higher number of components. This is joint work with M.V. Pavlov and G.V. Potemin.


Lunedì 8 luglio 2013
Ore 15:00, Aula 1B1, Dipartimento SBAI
Xavier Viennot (Università di Bordeaux)
The combinatorics of some exclusion model in physics
The PASEP model (partially asymmetric exclusion process) is a toy model in the dynamics of particles moving in a strip and has been extensively studied by physicists. They gave explicit expressions for the stationary probabilities of the associated Markov chain, in relation with some orthogonal polynomials and some quadratic algebras. More recently, combinatorists gave combinatorial solutions for this model, introducing some tableaux in bijection with permutations and, for the TASEP (totally asymmetric exclusion model) in bijection with binary trees. I will give an introduction to this hot and active subject, which is at the crossroad of physics, probability, algebra, combinatorics and computer science.


Martedì 9 luglio 2013
Ore 10:00, Accademia Nazionale dei Lincei
Convegno "Mathematics and Quantum Physics"
10:00 Shing-Tung Yau, Quasi-local mass and momentum in general relativity
11:00 Coffee break
11:30 Sebastiano Carpi, Conformal nets and noncommutative geometry
14:00 Christophe Salomon, Quantum simulations with ultracold atoms
15:00 Coffee break
15:30 Dorothea Bahns, Wavefront sets and Bochner type problems in quantum field theory
16:30 Masaki Izumi, Group actions on Kirchberg algebras
19:00 Noam Elkies, Canonical forms: a mathematician's view of musical canons


Mercoledì 10 luglio 2013
Ore 10:00, Accademia Nazionale dei Lincei
Convegno "Mathematics and Quantum Physics"
10:00 Joachim Cuntz, Number theory and operators on Hilbert space
11:00 Coffee break
11:30 Sergio Doplicher, The measurement process in local quantum theory
12:30 Rudolph Haag, Objects, events and reality in quantum physics


Mercoledì 10 luglio 2013
Ore 14:30, Aula Picone
Seminario di Algebra e Geometria
Ira Gessel (Brandeis University)
Quotients of the Malvenuto-Reutenauer algebra and permutation enumeration
The Malvenuto-Reutenauer algebra is an algebra spanned by permutations of [1, 2, ..., n] for all n, with multiplication defined by shifted shuffling. If we multiply two permutations of lengths m and n in this algebra we obtain a sum of "m choose n" permutations, so if we identify all permutations of the same length, we get a quotient of the Malvenuto-Reutenauer algebra that is isomorphic to the algebra of exponential generating functions. We would like to refine this observation by studying equivalence relations on permutations that correspond to quotients of the Malvenuto-Reutenauer algebra. These equivalence relations are most easily described by functions on permutations (permutation statistics) for which the equivalence classes are inverse images. One such permutation statistic is the inversion number. The quotient algebra is isomorphic to the algebra of Eulerian generating functions, and the relevant property is that if we shuffle a permutation of [1, 2, ..., m] with a permutation of [m+1, m+2, ..., m+n] then the inversions of the shuffles are counted by a q-binomial coefficient. The same property holds for the major index. Except for the inversion number, every permutation statistic that I know of with this property depends only on the descent sets of the permutations. The quotient of the Malvenuto-Reutenauer corresponding to the descent set statistic is the algebra of quasi-symmetric functions. I will discuss some quotients of the algebra of quasi-symmetric functions related to descents and peaks of permutations, and then I will discuss a generalization of quasi-symmetric functions corresponding to permutations that may have descents at the beginning or end, and a variation related to shuffles of circular permutations.


Giovedì 11 luglio 2013
Ore 10:00, Accademia Nazionale dei Lincei
Convegno "Mathematics and Quantum Physics"
10:00 Alain Connes, Recent advances in the spectral model
11:00 Coffee break
11:30 Robert Seiringer, Microscopic Derivation of Ginzburg-Landau theory
14:00 Gandalf Lechner, Non-local perturbations of hyperbolic PDEs and QFT on noncommutative spacetimes
15.00 Coffee break
15:30 Katarzyna Rejzner, Interplay between gravity and quantum physics from the point of view of general local covariance
16:30 Feng Xu, On some subfactor problems motivated by group theory
19:00 Alain Connes, The music of shapes


Giovedì 11 luglio 2013
Ore 11:00, Aula 1B1, Dipartimento SBAI
Ira Gessel (Brandeis University)
Hankel determinants, continued fractions, and orthogonal polynomials
There is a close connection between continued fractions, Hankel determinants, and orthogonal polynomials. Suppose that a sequence of polynomials is orthogonal with respect to a linear functional L. Then the numbers L(x^n) are called the moments of the orthogonal polynomial sequence. For many classical orthogonal polynomials these moments are sequences of combinatorial interest, such as Catalan numbers, factorials, Bell numbers, Euler numbers, and Genocchi numbers. Any sequence of orthogonal polynomials satisfies a three-term recurrence relation, in which, for classical orthogonal polynomials, the coefficients are given by simple formulas. The continued fraction for the generating function for the moments can be expressed simply in terms of these coefficients, as can the Hankel determinants of the moments. I'll talk about these ideas and describe some interesting examples.


Giovedì 11 luglio 2013
Ore 14:00, Aula D'Antoni, Università di Roma II
Dynamical Systems working seminars
Viviane Baladi (Università di Copenhagen)
Anisotropic spaces for discrete time Sinai billiards
I will explain how to modify the construction in my previous works with Gouezel on piecewise hyperbolic systems to handle singularities arising from billiards.


Giovedì 11 luglio 2013
Ore 14:30, Aula 211, Università di Roma III
Seminario di Geometria
Sofia Tirabassi (University of Utah)
Varieties with chi = 1 and q = 2n - 1
We present a joint work with Z. Jiang and M. Lahoz in which a complete classification of n-dimensional varieties of maximal Albanese dimesion with Euler characteristic 1, irregularity 2n-1. This extend in higher dimension results on surfaces by Beauville and Hacon-Pardini.


Venerdì 12 luglio 2013
Ore 10:00, Accademia Nazionale dei Lincei
Convegno "Mathematics and Quantum Physics"
10:00 Dan-Virgil Voiculescu, Free probability with left and right variables
11:00 Coffee break
11.30 Yasuyuki Kawahigashi, Operator algebras and tensor categories
14:00 Stefaan Vaes, Von Neumann algebras and ergodic theory of group actions
15:00 Coffee break
15:30 Claudia Pinzari, Connected components of compact matrix quantum groups
16:30 Detlev Buchholz, Long range interactions and structure of charge classes in QFT


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