Aula Mancini (SNS)

Crouzeix Conjecture

Relatore: 
Michael L. Overton

Crouzeix's conjecture is among the most intriguing developments in matrix theory in recent years.
Made in 2004 by Michel Crouzeix, it postulates that, for any polynomial p and any matrix A,
||p(A)|| <= 2 max(|p(z)|: z in W(A)), where the norm is the 2-norm and W(A) is the field
of values (numerical range) of A, that is the set of points attained by v*Av for some
vector v of unit length.  Crouzeix proved in 2007 that the inequality above 
holds if 2 is replaced by 11.08, and recently this was greatly improved by Palencia,

Data Seminario: 
Tuesday, June 25, 2019
Aula: 
Aula Mancini (SNS)
Ora Fine: 
Saturday, January 1, 0000 - 12:00
Affiliazione: 
Courant Institute of Mathematical Sciences, New York University
Ora Inizio: 
Saturday, January 1, 0000 - 11:00

MATLAB Tools for Large-Scale Linear Inverse Problems

Relatore: 
James Nagy

Inverse problems arise in a variety of applications: image processing, finance, mathematical biology, and more. Mathematical models for these applications may involve integral equations, partial differential equations, and dynamical systems, and solution schemes are formulated by applying algorithms that incorporate regularization techniques and/or statistical approaches.

Data Seminario: 
Friday, April 12, 2019
Aula: 
Aula Mancini (SNS)
Ora Fine: 
Saturday, January 1, 0000 - 12:00
Affiliazione: 
Department of Mathematics, Emory University
Ora Inizio: 
Saturday, January 1, 0000 - 11:00

Embedding properties of network realizations of reduced order models with applications to inverse scattering and data science

Relatore: 
Vladimir Druskin

Continued fractions are known since antiquity as the most compact representations of numbers. At the end of the 19th century Stieltjes connected them with physics. This connection gave rise to network syntheses in the first half of the 20th century that was at the base of modern electronics design and consecutively to model order reduction (MOR) that tremendously impacted many areas of engineering  by enabling efficient compression of the underlining dynamical systems.

Data Seminario: 
Thursday, March 21, 2019
Aula: 
Aula Mancini (SNS)
Ora Fine: 
Saturday, January 1, 0000 - 16:00
Affiliazione: 
Worcester Polytechnic Institute
Ora Inizio: 
Saturday, January 1, 0000 - 15:00

corso di Letture "Fourier–Mukai transforms in Algebraic Geometry"

L'argomento di queste due lezioni saranno le categorie derivate e i funtori
derivati. L'obiettivo è costruire la categoria derivata di una categoria
abeliana, dotarla di una struttura triangolata, dare e approfondire la
nozione di funtore derivato. Inevitabili sovrapposizioni con il corso di
Istituzioni di Algebra di due anni fa saranno il più possibile edulcorate,
in un sapiente processo di illusioni ottiche.
Questo capitolo conclude la sezione puramente categoriale, e fornisce gli

Data Seminario: 
Tuesday, February 12, 2019
Aula: 
Aula Mancini (SNS)
Ora Inizio: 
Saturday, January 1, 0000 - 09:00
Ora Fine: 
Saturday, January 1, 0000 - 11:00

Non-stationary substitutive dynamics and Pisot cocyles

Relatore: 
Milton Minervino
We work with shift spaces defined by infinite sequences of simple combinatorial rules called substitutions. To such a system we associate a renormalization cocycle, intimately related with a multidimensional continued fraction algorithm. Under suitable metric assumptions on the cocycle, namely the Pisot condition on the Lyapunov exponents, the shift space is measurably conjugate to an exchange of pieces on a fractal domain, known as Rauzy fractal.
Data Seminario: 
Tuesday, February 21, 2017
Aula: 
Aula Mancini (SNS)
Ora Fine: 
Saturday, January 1, 0000 - 14:30
Affiliazione: 
Aix-Marseille Université
Ora Inizio: 
Saturday, January 1, 0000 - 13:30

Renormalization and rotational attractors of two-dimensional dissipative dynamical systems

Relatore: 
Michael Yampolsky

We study dissipative rotational attractors in two settings: Siegel disks of Henon maps and minimal attractors of diffeomorphisms of the annulus. Jointly with D. Gaidashev, we extend renormalization of Siegel maps and critical circle maps to small 2D perturbations, and use renormalization tools to study the geometry of the attractors. In the Siegel case, jointly with D. Gaidashev and R. Radu we prove that for sufficiently dissipative Henon maps with semi-Siegel points with golden-mean rotation angles, Siegel disks are bounded by topological circles. In the annulus case, jointly with D.

Data Seminario: 
Monday, July 4, 2016
Aula: 
Aula Mancini (SNS)
Ora Fine: 
Saturday, January 1, 0000 - 14:00
Affiliazione: 
Univ. Toronto, Canada
Ora Inizio: 
Saturday, January 1, 0000 - 13:00

Seminario di Teoria dei numeri - Higher dimensional lemniscates: m particles in n-space with logarithmic potentials via complex analysis

Relatore: 
Fabrizio Catanese

What is a lemniscate? Given m points w_j  in n-dimensional space, consider the function F(x) which is the product of the distances |x-w_j|. A lemniscate  is defined to be a singular level set of  the function F, and the configuration of lemniscates is said to be generic if f= log(F) is a global Morse function.

Data Seminario: 
Tuesday, March 31, 2015
Aula: 
Aula Mancini (SNS)
Ora Fine: 
Saturday, January 1, 0000 - 16:30
Affiliazione: 
University of Bayreuth
Ora Inizio: 
Saturday, January 1, 0000 - 15:00

Seminario di Teoria dei numeri - Higher dimensional lemniscates: m particles in n-space with logarithmic potentials via complex analysis

Relatore: 
Fabrizio Catanese

What is a lemniscate? Given m points w_j  in n-dimensional space, consider the function F(x) which is the product of the distances |x-w_j|. A lemniscate  is defined to be a singular level set of  the function F, and the configuration of lemniscates is said to be generic if f= log(F) is a global Morse function.

Data Seminario: 
Tuesday, March 31, 2015
Aula: 
Aula Mancini (SNS)
Ora Fine: 
Saturday, January 1, 0000 - 16:30
Affiliazione: 
University of Bayreuth
Ora Inizio: 
Saturday, January 1, 0000 - 15:00

Seminario di Teoria dei Numeri - "Teoria Geometrica degli Invarianti e il Teorema di Roth"

Relatore: 
Marco Maculan

Abstract:

Il teorema di Roth afferma che, dato un numero algebrico, i numeri razionali che lo approssimano "molto bene" sono in numero finito. La dimostrazione di Roth di questo risultato si basa sul lavoro di Thue (1909) e, benché ci siano state considerevoli migliorazioni nelle singole tappe, la strategia generale è restata immutata.

Data Seminario: 
Tuesday, November 18, 2014
Aula: 
Aula Mancini (SNS)
Ora Fine: 
Saturday, January 1, 0000 - 16:00
Affiliazione: 
Université Paris-Sud
Ora Inizio: 
Saturday, January 1, 0000 - 15:00

Contare punti di altezza limitata

Relatore: 
Fabrizio Barroero

L'altezza di Weil è una funzione che misura la complessità aritmetica di un numero algebrico.
Un famoso teorema, dovuto a Northcott, assicura la finitezza degli insiemi di vettori di numeri
algebrici di grado e altezza uniformemente limitati.
E' dunque naturale cercare di studiare la cardinalità di questi insiemi e, in particolare, cercare
formule asintotiche quando il limite dell'altezza tende a infinito.
Richiameremo alcuni risultati più o meno recenti di diversi autori e, in seguito, passeremo al problema

Data Seminario: 
Monday, April 14, 2014
Aula: 
Aula Mancini (SNS)
Ora Fine: 
Saturday, January 1, 0000 - 17:00
Affiliazione: 
SNS di Pisa
Ora Inizio: 
Saturday, January 1, 0000 - 15:45
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