Notiziario Scientifico
a cura del Dipartimento di Matematica G. Castelnuovo, Sapienza Università di Roma
Settimana dal 08-06-2020 al 14-06-2020
Lunedì 08 giugno 2020
Ore 14:00, Teleconferenza, collegarsi al link https://meet.google.com/pip-kvzt-fkz, Dipartimento di Fisica, Università di Roma La Sapienza
Seminario delle Meccaniche
Alessandro Giuliani (Università di Roma 3)
2D Ising models with finite range interactions: scaling limit of the critical theory in the cylinder
We consider non-integrable perturbations of the nearest neighbor Ising model in two dimensions in a discrete cylinder of arbitrary aspect ratio and lattice mesh \(\epsilon\). We show that, if we appropriately fix the temperature and let \(\epsilon\) to zero, the rescaled multipoint energy correlations converge to a well defined limit, which is the same as the one for the integrable Ising model, up to a finite, analytic, multiplicative renormalization constant. In particular, the limit is conformally covariant under changes of the aspect ratio of the cylinder. The proof is based on constructive Renormalization Group methods. Compared to previous results on the subject, an important (technical and conceptual) novelty consists of the treatment of edge effects, whose presence induce the appearance of boundary running coupling constants; the flow of such constants is controlled thanks to cancellations at the boundary, related to an approximate image rule. Joint work with G. Antinucci and R. Greenblatt.
Lunedì 08 giugno 2020
Ore 14:30, meet.google.com/mwn-midi-gxh
seminario di Analisi Matematica--AMACA
Luca Di Fazio (Dpt Matematica Sapienza U. di Roma)
Regolarità \(C^1\) nel problema dell'ostacolo sottile per disequazioni variazionali
In questo seminario parlerò di un risultato di regolarità a priori delle soluzioni di problemi di minimo con ostacolo sottile. Supponendo le soluzioni Lipschitziane infatti, si scopre che esse sono in realtà di regolarità \(C^1\) su ognuno dei due lati dell'ostacolo. Si estende così un risultato di J. Frehse del '77 sotto ipotesi leggermente più restrittive. Il risultato fa parte del mio programma di dottorato con il Prof. E. N. Spadaro.
Lunedì 08 giugno 2020
Ore 15:00, meet.google.com/mwn-midi-gxh
seminario di Analisi Matematica--AMACA
Andrea Kubin (Dpt Matematica Sapienza u. di Roma)
Potenziali di interazione tra sfere rigide di tipo Riesz
Abbiamo introdotto un modello per delle energie di interazione tra sfere rigide, tipo potenziali di Riesz, e ne abbiamo studiato il limite termodinamico.
Martedì 09 giugno 2020
Ore 15:00, On-line event, Dipartimento di Matematica, Università di Roma "Tor Vergata"
May12 Event
Lucia Caporaso (Università Roma Tre)
Varieties of varieties after Mirzakhani
The lecture will be followed by the screening of the documentary: "Secrets of the surface: the mathematical vision of Maryam Mirzakhani" by George Csicsery. The event will be live-streamed on the youtube channel: https://www.youtube.com/channel/UCYj2TA5j363-eQK391WjqoA More information will be posted on the web-page: http://www.mat.uniroma2.it/may12.php The event is sponsored by the MIUR Excellence Department Project CUP E83C18000100006
Martedì 09 giugno 2020
Ore 15:00, ZOOM Meeting ID: 962 612 6392 Pwd: mdn906, Dipartimento di Matematica, Sapienza
Seminario di Modellistica Differenziale Numerica On-Line
Emanuele Macca (Dottorato in Matematica, Università di Catania)
An order-adaptive compact approximation Taylor method for systems of conservation laws
Lax-Wendroff methods for linear systems of conservation laws are based on Taylor expansions in time in which the time derivatives are transformed into spatial derivatives using the governing equations. The main difficulty to extend Lax-Wendroff methods to nonlinear problems comes from the transformation of time derivatives into spatial derivatives through the Cauchy-Kovalesky (CK) procedure: this approach may indeed be impractical from the computational point of view because it often requires extended symbolic calculus, ended up into inefficient codes. For this reason, a new family of high-order shock-capturing finite difference numerical methods for systems of conservation laws, based on the numerically CK procedure, are presented. These methods, called Adaptive Compact Approximation Taylor (ACAT) schemes, use centered (2p + 1)-point stencils, where p may take values in {1, 2,..., P}, and a new family of smoothness indicators defined in the stencils.
Per informazioni, rivolgersi a: falcone@mat.uniroma1.it
Martedì 09 giugno 2020
Ore 15:45, ZOOM Meeting ID: 962 612 6392 Pwd: mdn906, Dipartimento di Matematica, Sapienza
Seminario di Modellistica Differenziale Numerica On-Line
Andrea Pesare (Dottorato in Matematica, Sapienza)
An optimal control approach to Reinforcement Learning
We consider an optimal control problem where the exact dynamics is unknown and only a probability distribution π on the vector field is given. The associated optimal control problem tries to minimize an average cost, where the average is made over the ensemble given by π. Our goal is to determine if the value function and the optimal control of this average cost problem converge respectively to the value function and the optimal control of the classical optimal control problem with underlying dynamics f, when the distribution π gets closer and closer to the Dirac delta on the vector field f. Finally, we show how this result can give a better understanding of some Reinforcement Learning algorithms.
Per informazioni, rivolgersi a: falcone@mat.uniroma1.it
Mercoledì 10 giugno 2020
Ore 15:00, ** Si prega di collegarsi alcuni minuti prima per essere ammessi al meeting ** streaming Microsoft Teams, a questo link, Dipartimento di Matematica e Fisica, Università di Roma Tre
Discussione di tesi di dottorato
Fabrizio Anella (Università di Roma 3)
Rational curves on Calabi-Yau fiber spaces and Twisted cotangent bundles of Hyperkähler manifolds
Mercoledì 10 giugno 2020
Ore 16:30, **ATTENZIONE AL CAMBIO ECCEZIONALE DI ORARIO** streaming all'indirizzo https://meet.google.com/vsz-nxkm-hav, Dipartimento di Matematica, Sapienza Università di Roma
seminario di Algebra e Geometria
Valentino Tosatti (Northwestern University)
Metric limits of Calabi-Yau manifolds
I will discuss the problem of understanding the behavior of degenerating families of Ricci-flat Kähler metrics on a Calabi-Yau manifold, and what their possible metric limits are. I will explain what we know in general about such metric limits, what techniques are used to approach these questions, and what applications these results have. Based on joint works with Gross-Zhang and with Hein.
Mercoledì 10 giugno 2020
Ore 17:00, On line seminar, Web site for information: https://www.dinamici.org/dai-seminar/
DinAmicI: Another Internet Seminar (DAI Seminar)
Marta Maggioni (Universiteit Leiden (Netherlands))
Matching for random systems with an application to minimal weight expansions
We consider families of skew-product maps, representing systems evolving in discrete time in which, at each time step, one of a number of transformations is chosen according to an i.i.d process and applied. We extend the notion of matching for such dynamical systems and we show that, for a certain family of piecewise affine random maps of the interval, the property of random matching implies that any invariant density is piecewise constant. We give an application by introducing a one-parameter family of random maps generating signed binary expansions of numbers. This family has random matching for Lebesgue almost every parameter, producing matching intervals that are related to the ones obtained for the Nakada continued fraction transformations. We use this property to study the expansions with minimal weight. Joint with K. Dajani, and C. Kalle. Note: The zoom link to the seminar will be posted on https://www.dinamici.org/dai-seminar/ and on https://mathseminars.org/seminar/DinAmicI. Moreover, it will be streamed live on youtube via the DinAmicI channel: https://www.youtube.com/channel/UCyNNg155G3iLS7l-qZjboyg
Per informazioni, rivolgersi a: sorrentino@mat.uniroma2.it
Venerdì 12 giugno 2020
Ore 14:30, Videoconference talk - join it via this link (Teams Conference ID: 242 091 693#), dipartimento di Matematica - Università di Roma "Tor Vergata"
ARTS - Algebra and Representation Theory Seminar
Sabino DI TRANI (Università di Firenze)
The Reeder's Conjecture for Classical Lie Algebras
A well known result of the first half of XX century asserts that the cohomology of a compact connected Lie group G is isomorphic as a graded vector space to the ring of G-invariants of the exterior algebra of g = Lie(G) . Finding Betti numbers of G then corresponds to identifying copies of the trivial representation in Λg . Reeder in '95 reduces this computation to the problem of finding copies of the trivial representation of the Weyl group of G in a suitable bi-graded algebra. As a generalization of this result, he conjectured that it is possible to compute the graded multiplicites in Λg of a special class of representations reducing to a similar “Weyl group representation”-problem. In the talk I will give a proof of the Reeder's Conjecture for the Cn case and present some new progress for type D.
Warning: the talk will be held in streaming, as a videoconference on-line; in order to join the videoconference, follow this link (Teams Conference ID: 242 091 693#).
Per informazioni, rivolgersi a: gavarini@mat.uniroma2.it
Venerdì 12 giugno 2020
Ore 15:00, Modalità telematica, Dipartimento di Matematica e Fisica, Università degli Studi RomaTre
Seminario di Logica e Informatica Teorica
Michele Abrusci (Università degli Studi Roma Tre)
Proof-nets and laws of Categorial Grammar
I present a geometrical analysis – i.e. by means of proof nets of the multiplicative fragment of Cyclic Linear Logic - of the principles that lay at the basis of Categorial Grammar and of the Lambek Calculus: Residuation laws, Monotonicity laws, Application laws, Expansion laws, Type-raising laws, Composition laws, Geach laws and Switching laws. This geometrical analysis leads to better understand these laws, and to discover some laws have a common geometrical representation (the proofs of Application laws, Expansion Laws and Type-reasing laws are represented by proof-nets with two axiom links, whereas the proofs of Composition laws, Geach laws and Switching laws are represented by proof-nets with three axiom links). The talk is based on a joint work with Claudia Casadio.
Per partecipare al seminario, richiedere il link all’indirizzo email vitomichele.abrusci@uniroma3.it o cliccare sul seguente link Teams meeting: link
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