Cari colleghi
vi ricordo che lunedì prossimo 7 marzo alle ore 16 avranno luogo i prossimi due seminari nella serie Prisma; gli speaker sono Pietro Caputo e Vittoria Silvestri. I seminari avranno luogo come sempre sulla piattaforma teams; i dettagli per il collegamento e la lista completa dei seminari si possono trovare qui:
http://www.umi-prisma.polito.it/webinars.html
Qui sotto titoli ed abstract, grazie per l'attenzione, Domenico Marinucci
----------------------------------------------------------------------------
Speaker: Pietro Caputo, Roma III
Title: Random walks on directed random networks
Abstract: Exploration via random walks is often very useful for the analysis of directed networks. For instance, the walk's stationary distribution plays a prominent role in ranking systems and search algorithms. In this lecture, we present some recent progress in the analysis of random walks for a class of sparse directed networks generated by the so-called configuration model. We discuss various properties of the stationary distribution, including bulk behaviour and extremal values. We also consider the mixing time, that is the time needed to reach stationarity, and show that the walk typically displays a cutoff behaviour. Moreover, we discuss the asymptotic behaviour of the cover time, that is the expected time it takes the random walk to cover the whole network. Finally, we analyse the convergence to stationarity when the walk experiences regeneration events such as teleportation, as in the PageRank algorithm, or resampling of the underlying graph, as in a dynamically evolving network.
------------------------------------------------------------ Speaker: Vittoria Silvestri, Sapienza
Title: Internal DLA on cylinder graphs: typical profiles and mixing.
Abstract: Internal DLA is a mathematical model for the growth of a random cluster of particles according to the harmonic measure on the cluster boundary, seen from an internal point. Performing IDLA on cylinder graphs (i.e. graphs of the form GxZ) gives a Markov chain on the infinite space of particle configurations. We show that this chain is positive recurrent, and give a description of typical (i.e. stationary) configurations. We then analyse the mixing time of this chain.