Bollettino settimanale
Settimana 16/10/2023 - 20/10/2023
Seminari
Università degli Studi Roma Tor Vergata
Dipartimento di Matematica
Rome Centre on Mathematics for Modelling and Data ScienceS - RoMaDS SEMINAR
Date: 19th October
Schedule: 14:00 - Rome Time
Where: Conference Room "R. Dal Passo"
Title First Semninar: " The Strong Lottery Ticker Hypothesis and the Random Subset Sum Problem "
Speaker: Francesco D'Amore Aalto University, Espoo
Abstract: IThe Strong Lottery Ticket Hypothesis (SLTH) posits that randomly-initialized neural networks contain subnetworks (strong lottery tickets) that achieve competitive accuracy when compared to sufficiently small target networks, even those that have been trained. Empirical evidence for this phenomenon was first observed by Ramanujan et al. in 2020, spurring a line of theoretical research: Malach et al. (2020), Pensia et al. (2020), da Cunha et al. (2022), and Burkholz (2022) have analytically proved formulations of the SLTH in various neural network classes and under different hypotheses. In this presentation, we provide an overview of the state-of-the-art theoretical research on the SLTH and its connection with the Random Subset Sum (RSS) problem in theoretical computer science. While previous works on the SLTH ensure that the strong lottery ticket can be obtained via unstructured pruning, we demonstrate how recent advances in the multidimensional generalization of the RSS problem can be leveraged to obtain forms of structured pruning. Additionally, we highlight how refining the RSS results would yield tighter formulations of the SLTH. This presentation is based on a joint work with Arthur da Cunha and Emanuele Natale that will be presented at NeurIPS 2023.
Title Second Semninar: " Distributed Self-Stabilizing MIS Algorithms "
Speaker: Isabella Ziccardi (Università Bocconi)
Abstract: I will discuss self-stabilizing distributed algorithms that find a Maximal Independent Set in an n-vertex graph. These algorithms share the feature of utilizing randomization to break symmetry. I will compare them based on the following parameters: the number of states used by each node, the knowledge of the graph required by each node, and their stabilization time. The first three algorithms are obtained by reconsidering some existing algorithms and making them self-stabilizing by introducing additional states. The first algorithm gets along with three states, but each node must have knowledge of ∆, the maximum node degree. In the second algorithm, nodes only need to be aware of their degree, but each node v has O(∆(v)) states, where ∆(v) is the degree of v. The third algorithm also requires O(∆(v)) states for each node v, but it works in the restricted beeping communication model. All three algorithms stabilize in O(log n) rounds with high probability. Lastly, I will talk about two algorithms that aim to create self-stabilizing algorithms with a constant number of states while requiring no knowledge of the underlying graph. The first algorithm is a natural process that, despite its simplicity, has received limited attention in the literature. It stabilizes in O(polylog(n)) rounds for specific graph families but may exhibit slower convergence time on general graphs. The final algorithm is a modification of this simple process, that tries to fix the particular situations that slow down the convergence.
Organizing Committee:
Michele Salvi (mail to contact)
Domenico Marinucci (mail to contact)
Further Info: Click here for RoMaDS Page
Streaming Link (MS Teams): This seminar will be held: mix mode in person and streaming
Università degli Studi Roma Tor Vergata
Dipartimento di Matematica
Operators Algebras Seminar
Date: 18th October
Schedule: 16:00 - Rome Time
Where: Conference Room " Room 2001 "
Title : " Nonlocal games and Grothendieck's inequalities "
Speaker: Valerio Proietti (University of Oslo)
Abstract: I will explore some recent results based on the interaction of operator space theory and quantum nonlocality. In particular I will emphasize the connection between large violations of Bell inequalities and certain norms in Banach and operator space categories. Finally, using Grothendieck's inequality, I will derive some interesting consequences for the parallel repetition problem in the context of XOR games.
Organizing Committee:
Vincenzo Morinelli (mail to contact)
Roberto Longo (mail to contact)
Further Info: Click here for RoMaDS Page
Streaming Link (MS Teams): This seminar will be held in person mode
Università degli Studi di Roma "Tor Vergata"
Dipartimento di Matematica
Algebra and Representation Theory Seminar
Date: Friday 20th October
Schedule: 14:30 Rome Time
Where: Conference Room 1201 “Roberta Dal Passo”
Speaker: Luca Francone (Université "Claude Bernard" Lyon 1 )
Title: "Minimal monomial lifting of cluster algebras and branching problems"
Abstract:
We will talk about minimal monomial lifting of cluster algebras. That is sort of a homogenisation technique, whose goal is to identify a cluster algebra
structure on some schemes "suitable for lifting", compatibly with a base cluster algebra structure on a given subscheme. We will see how to apply this
technique to study some branching problems, in representation theory of complex reductive groups and, time permitting, we will discuss some possible development
as the construction of polyhedral models for multiplicities.
NOTE: This talk is part of the activity of the MIUR Excellence Department Project Mat-Mod@TOV (CUP E83C23000330006)
Organizing Committee:
Fabio Gavarini (mail to)
Martina Lanini (mail to)
Further Info: Click here for webpage
Streaming Link (MS Teams): This seminar will be held in person
Università degli Studi di Roma "Tor Vergata"
Dipartimento di Matematica
Algebra and Representation Theory Seminar
Date: Friday 20th October
Schedule: 16:00 - Rome Time
Where: Conference Room 1201 “Roberta Dal Passo”
Speaker: Misha FEIGIN University of Glasgow
Title: " Quasi-invariants and free multi-arrangements "
Abstract:
Quasi-invariants are special polynomials associated with a finite reflection group W and a multiplicity function.
They appeared in 1990 in the study of Calogero-Moser integrable systems by Chalykh and Veselov, in which case they are the highest
symbols of differential operators which form a large commutative ring. Similarly to all the polynomials, quasi-invariants form a
free module over invariant polynomials of rank |W|, and they have other good properties. Quasi-invariants form representations of spherical
Cherednik algebras as was established by Berest, Etingof and Ginzburg in 2003, which gives a way to establish the freeness property.
I am going to explain a more recent application of quasi-invariants to the theory of free multi-arrangements of hyperplanes.
In this case one is interested in the module of logarithmic vector fields which is known to be free over polynomials for some arrangements including Coxeter ones.
Quasi-invariants can be used to construct elements of this module, and they also lead to new free multi-arrangements in the case of complex reflection groups.
The talk is based on a joint work with T. Abe, N. Enomoto and M. Yoshinaga.
NOTE: This talk is part of the activity of the MIUR Excellence Department Project Mat-Mod@TOV (CUP E83C23000330006)
Organizing Committee:
Fabio Gavarini (mail to)
Martina Lanini (mail to)
Further Info: Click here for webpage
Streaming Link (MS Teams): This seminar will be held in person
Università degli Studi Roma Tor Vergata
Dipartimento di Matematica
Geometry Seminar
Date: 17th October
Schedule: 14:30 - Rome Time
Where: Conference Room "R. Dal Passo"
Title: " On Syzygy schemes"
Speaker: Andrea Bruno ( Università Roma Tre)
Abstract:
If X is a projective variety cut out by quadrics, the p^th Syzygy scheme Syz_p(X) is the scheme cut out by quadrics involved in a p^th syzygy of X, and it turns out to capture refined geometrical properties of X in its embedding.
We report on joint work in progress with M. Aprodu and E. Sernesi,
concerning the second Syzygy scheme Syz_2(C) of a smooth curve in case C is embedded either by the canonical line bundle or by a non-special line bundle L,
aiming at a classification of all (C,L) such that Syz_2(C) strictly contains
Note: the seminar are part of the activity of the MIUR Excellence Department Projects MathMod@TOV, and the Prin 2022 Moduli Spaces and Birational Geometry.
Organizing Committee:
Giulio Codogni (mail to contact)
Guido Maria Lido (mail to contact)
Further Info: Click here for RoMaDS Page
Streaming Link (MS Teams): This seminar will be held: mix mode in person and streaming
Eventi