Categoria: Events

Speaker: Daniele Catanzaro

Abstract: Recent advances on the polyhedral combinatorics of the Balances Minimum Evolution Problem (BMEP) enabled the characterization of a number of facets of its convex hull (also referred to as the BMEP polytope) as well as the discovery of connections between this polytope and the permutoassociahedron. In this article, we extend these studies, by presenting new results concerning some fundamental characteristics of the BMEP polytope, new facet-defining inequalities in the case of six or more taxa, a number of valid inequalities, and a polynomial time oracle to recognize its vertices. Our aim is to broaden understanding of the polyhedral combinatorics of the BMEP with a view to developing new and more effective exact solution algorithms.

Aula: Sala Riunioni VI piano
Data: 26 Febbraio 2020 – ore 11.30

Speaker: Nicolò Gusmeroli
Location: Roma, Via dei Taurini 19, Sala Riunioni VI Piano
Date:  November 7, 2019  time 11.30 
Contact person: Claudio Gentile

Citation from the ACM website: For conceptual and engineering breakthroughs that have made deep neural networks a critical component of computing. https://amturing.acm.org/award_winners/bengio_3406375.cfm.

Yosha Bengio will be lecturer at the 1st MINOA PhD school  “Mixed-Integer Nonlinear Optimization meets Data Science” organized by CNR-IASI that will be held on June 25-28 at Ischia (NA), Italy.

CNR-IASI, as part of the Marie Sklodowska-Curie ETN MINOA (http://minoa-itn.fau.de), announces the school for PhD students and post-docs on the theme Mixed Integer Non linear Optimization meets Data Science. The school will be held on June 24-28, 2019 in Ischia (Italy) at Hotel Hermitage. See www.iasi.cnr.it/minoa/big-data-school for information and registrations.

Speaker: Fabio Furini – LAMSADE, Université Paris Dauphine

Abstract: We study the two player zero-sum Stackelberg game in which the leader interdicts (removes) a limited number of vertices from the graph, and the follower searches for the maximum clique in the interdicted graph. The goal of the leader is to derive an interdiction policy which will result in the worst possible outcome for the follower. This problem has applications in many areas, such as crime detection, prevention of outbreaks of infectious diseases and surveillance of communication networks. We design an exact solution framework basedon a Bilevel Integer Linear Programming model. Thanks to the study of the polytope of the corresponding single-level reformulation, we derive a branch-and-cut algorithm and enhance it by tight combinatorial lower and upper bounds, which also allow for a drastic reduction of the size of the input graph. Our model is based on an exponential family of Clique-Interdiction Cuts whose separation requires solving the maximum clique problem. We derive an effective separation procedure based on a newly developed combinatorial algorithm that is tailored for finding maximum cliques in interdicted graphs. We assess the applicability and the limits of our exact framework on publicly available instances, including large-scale social networks with up to one hundred thousand vertices and three million edges. Most of these instances are solved to provable optimality within short computing times. Our code (which will be also publicly available) allows to analyze the resilience of (social) networks with respect to vertex-interdiction attacks, i.e., the decrease of the size of the maximum clique in function of incremental interdiction budget level.
Location: Roma, Via dei Taurini 19, Aula Piano Terra
Date:  December 21, 2018  time 11.30 
Contact person: Claudio Gentile

Perspective Cuts for the ACOPF with generators by Esteban Salgado (CNRS-LIX), Claudio Gentile (IASI-CNR) and Leo Liberti (CNRS-LIX).

Perspective Reformulation-based Strengthening for the sequential convex MINLP technique by Claudio D’Ambrosio (CNRS-LIX), Antonio Frangioni (University of Pisa), and Claudio Gentile (IASI-CNR).