In a wide range of applications it is required to replace an empirically obtained unit diagonal indefinite symmetric matrix with a valid correlation matrix (unit diagonal positive semidefinite matrix). A popular replacement is the nearest…
Categoria evento: Seminars
Annealed and quenched central limit theorem for random dynamical systems – Romain Aimino (Roma 2)
For random dynamical systems, one can distinguish two kinds of limit theorems: annealed results, which refer to the Birkhoff sums seen as functions of both the phase space variable and the choice of the maps composed, and quenched results, which…
Optimization & Numerical Analysis seminars. Fast Computation of Centrality Indices – Caterina Fenu – Università di Pisa (Il Seminario si svolgerà nella Sala Seminari Ovest, Dipartimento Informatica.)
One of the main issues in complex networks theory is to find the “most important” nodes. To this aim, one can use matrix functions applied to its adjacency matrix. After an introduction on the use of Gauss-type quadrature rules, we will discuss a…
Perturbations of variational evolutions – Andrea Braides (Universita’ di Roma “Tor Vergata)
The notion of minimizing movement (Almgren-Taylor-Wang, De Giorgi), which has been used to give a general definition of gradient flow (Ambrosio-Gigli-Savaré) can also be used to study a “homogenized” motion for a family of functionals depending on a…
Lipschitz Metrics for Nonlinear Wave Equations – Alberto Bressan (Penn State University)
The talk is concerned with some classes of nonlinear wave equations: of first order, such as the Camassa-Holm equation, or of second order, as the variational wave equation $u_{tt} – c(u) (c(u)u_x)_x=0$. In both cases, it is known that the equations…
Optimal transport with relativistic cost: continuity and Kantorovich potentials for generic cost functions – Jean Louet
The optimal transport problem consists in minimizing the total energy of the displacement among all the (vector-valued) functions having prescribed image measure. In this talk we are interested in a particular case of cost functions: c is given by…
Discrete to continuum limits of fully atomistic and quasicontinuum systems with potentials of Lennard-Jones type – Anja Schloemerkemper
In recent years several engineering models, e.g., in the context of elasticity theory, were justified by a discrete to continuum analysis, i.e., by a passage from discrete/atomistic systems to continuum problems. I will present results with M.…
Bordi all’infinito di filling di Dehn algebrici – Alessandro Sisto (ETH Zurich)
Il filling di Dehn è un importante metodo per costruire 3-varietà iperboliche chiuse a partire da 3-varietà iperboliche di volume finito. Questa costruzione ha un analogo algebrico per gruppi relativamenteiperbolici, e ne studieremo l’effetto sul…
A variational approach to nonlocal and crystalline curvature flows – Marcello Ponsiglione (Università di Roma La Sapienza)
In this seminar I will introduce a generalized notion of (local and nonlocal) perimeter and curvature. Then, I will describe the corresponding geometric flows, showing the coherence between variational methods (based on the minimizing movements…
Newton’s method as an unexpectedly efficient root finder – Dierk Schleicher (Jacobs University, Bremen, Germany)
Newton’s method is well known as a root finder locally near the roots. It is often “not recommended” as a global root finder because of its “chaotic” properties. We give a very efficient theoretical upper bound on its speed of convergence: all roots…