Category: Events

CITI seminar – Martin Kumm (University of Applied Sciences Fulda, Germany) – 13/11 at 10:30AM

Title: Design of Optimal Multiplierless FIR Filters

Date and Place: 13 / 11 / 2019 10:30 in TD-C

Speaker: Martin Kumm (University of Applied Sciences Fulda, Germany)

Host: Florent de Dinechin

Abstract:
In this talk we present a novel method for the simultaneous design of digital filters adhering to a given frequency specification and its dedicated (hardware) implementation. Our methods are based on an integer linear programming (ILP) problem and aim to minimize the number of adders used to implement a digital filter. In the first part, an overview is given about the structure of finite impulse response (FIR) filters which typically contain many costly multiplications. As these are usually multiplications by a constant, they can be reduced to additions, subtractions and bit-shifts, leading to a multiplierless realization. A brief overview of state-of-the-art methods for optimizing constant multiplications is presented. In the second part, novel extensions are presented that also consider the frequency specification of the digital filter in the optimization. Compared to previous multiplierless FIR approaches, the methods introduced here ensure adder count optimality. We show the effectiveness by solving established design problems: our results either prove existing heuristics to be optimal or improve their adder count.

Biography:
Martin Kumm is full professor in the faculty of Applied Computer Science at the University of Applied Sciences Fulda in Germany. His research interests are arithmetic circuits and their optimization in the context of reconfigurable systems (FPGAs). http://www.martin-kumm.de/


CITI Seminar of Erwan Le Merrer / Gilles Tredan (Inria-Rennes / LAAS-CNRS) on October 9 at 3pm

Title: The Bouncer Problem: Challenges to Remote Explainability

Date and Place: 09 / 10 / 2019 3PM in 432 (Antenne Inria)

Host: Privatics

Abstract:
The concept of explainability is envisioned to satisfy society’s demands for transparency on machine learning decisions. The concept is simple: like humans, algorithms should explain the rationale behind their decisions so that their fairness can be assessed. While this approach is promising in a local context (e.g. to explain a model during debugging at training time), we argue that this reasoning cannot simply be transposed in a remote context, where a trained model by a service provider is only accessible through its API. This is problematic as it constitutes precisely the target use-case requiring transparency from a societal perspective. Through an analogy with a club bouncer (which may provide untruthful explanations upon customer reject), we show that providing explanations cannot prevent a remote service from lying about the true reasons leading to its decisions.

More precisely, we prove the impossibility of remote explainability for single explanations, by constructing an attack on explanations that hides discriminatory features to the querying user. We provide an example implementation of this attack. We then show that the probability that an observer spots the attack, using several explanations for attempting to find incoherences, is low in practical settings. This undermines the very concept of remote explainability in general.

Biography:
Erwan is on an “advanced research position” at Inria, in the WIDE team, since Nov. 2018. He was previously senior research scientist at Technicolor R&I (2009-2018). Gilles is a “chargé de recherches” at CNRS since 2011.


CITI Seminar of Subhash Lakshminarayana (University of Warwick’s School of Engineering) on September 19 at 2pm

Title: On False Data Injection Attacks Against Power Grids and Countermeasures

Date and Place: 19 / 09 / 2019 2PM in TD-C

Host: Samir M. Perlaza

Abstract:
The power grid state estimation (SE) has been shown to be vulnerable to false data injection (FDI) attacks, which can lead to severe consequences, e.g., transmission line trips, unsafe frequency excursions and/or economic losses. In this talk, we will examine the security of power gird SE from both the attacker and the defender’s perspective. For the former, we examine data-driven FDI attacks, i.e., constructing FDI attacks that can bypass the grid’s bad-data detector (BDD) by accessing its measurement data over a period of time. We characterize important tradeoffs for the attacker in this context between the attack’s spatial and temporal efficiency. The results provide us with an understanding for designing defense mechanism to thwart such attacks. For defense, we propose a hardened-attack detector based on moving-target defense (MTD) that actively perturbs transmission line reactances to invalidate the attacker’s knowledge. We present novel formal design criteria to select MTD reactance perturbations that are truly effective. Moreover, based on a key optimal power flow formulation, we find that the effective MTD may incur a non-trivial operational cost. Accordingly, we characterize important tradeoffs between the MTD’s detection capability and its associated required cost. Extensive simulations, using the MATPOWER simulator and benchmark IEEE bus systems, verify and illustrate the proposed design approach.

Biography:
Subhash Lakshminarayana is an assistant professor in the University of Warwick’s School of Engineering since September 2018. Prior to joining Warwick, he worked as a research scientist at the Advanced Digital Sciences Center (ADSC) in Singapore between 2015-2018. Before that, he held joint post-doctoral researcher appointment at Princeton University and the Singapore University of Technology and Design (SUTD) between 2013-2015. He received his PhD in the field of Wireless Communications at the Department of Telecommunications at Ecole Superieure d’Electricite (Supelec) Paris, France, M.S. degree from The Ohio State University, USA and B.S. from Bangalore University in India. His research interests include cyber-physical system security (power grids and urban transportation) and wireless communications. His works have been selected among the Best Conference Papers at the IEEE Power Energy Society General Meeting (PESGM) 2015 conference, and the Best 50 Papers at the IEEE Globecom 2014 conference.


CITI Seminar of Christine Solnon (INSA-Lyon-LIRIS) on September 26 at 2pm

Title: Time-Dependent and Stochastic Vehicle Routing Problems

Date and Place: 26 / 09 / 2019 14:00 in TD-C

Host: Florent de Dinechin

Abstract:
Smart cities are equipped with sensors which monitor traffic speed. The exploitation of these data to optimise urban deliveries has given rise to new challenging problems, and I’ll focus on two of them: – Time-Dependent Vehicle Routing Problems, which take into account variations of travel speeds during the day; – Stochastic Vehicle Routing Problems, where uncertain data are represented by random variables.

Biography:
Christine Solnon is Professor in the Computer Science Department of INSA Lyon, and member of the LIRIS lab.


PhD Defence: “Contributions Théoriques sur les Communications Furtives”, David KIBLOFF, Chappe Amphitheater, CITI, 17th of September 2019 at 14h00

Title

Information Theoretic Contributions to Covert Communications

Abstract

The problem of covert communications, also known as communications with low-probability of detection has gained interest in the information theory community in the last years. Since Bash et. al. showed in 2012 that the square-root law applied in the point-to-point case for such communications systems, the number of contributions on the topic did not cease to grow. In this thesis, two new problems of covert communications are introduced. First, the problem of covert communications over a point-to-point link where a warden observes only a fraction of channel outputs in order to try to detect the communications is studied. An achievability bound in the finite block-length regime is derived for this problem. Second, the problem of embedding covert information into a given broadcast code is introduced. Given a broadcast code to transmit a common message to two receivers, the goal is to determine the maximum number of information bits that can be reliably sent to one receiver while remaining covert with respect to the other receiver. For this problem, both an achievability and converse bound in the asymptotic block-length regime are derived for a particular class of channels, i.e., symmetric channels. Together these bounds characterize the maximum number of information bits that can be covertly embedded in a given broadcast code for symmetric channels.

 

Jury

  • Dr. Albert Guillen i Fabregas, Université Pompeu Fabra, Espagne. Rapporteur.
  • Dr. Aline Roumy, INRIA, France. Rapporteure.
  • Dr. Laurent Clavier, IMT Lille Douai, France. Examinateur.
  • Dr. Inbar Fijalkow, Université de Cergy-Pontoise, France. Examinatrice.
  • Dr. Jean-Marie Gorce, INSA de Lyon, France. Examinateur.
  • Dr. Ligong Wang, CNRS, France. Examinateur.
  • Dr. Guillaume Villemaud, INSA de Lyon, France. Directeur de thèse.
  • Dr. Samir M. Perlaza, INRIA, France. Encadrant de thèse.
  • Dr. Ronan Cosquer, DGA, France. Invité.

Save the date: Atelier “algorithmes en boite-noire” – October 10, Lyon

Atelier “algorithmes en boite-noire”
Etat des lieux et réaction face à une exposition massive aux décisions algorithmiques.
Le 10 Octobre 2019 à Lyon

http://atelier-blackbox.conf.citi-lab.fr

Les technologies de l’information et de la communication transforment la
société. Les algorithmes sont au coeur de toutes les attentions: objets
industriels fondamentaux pour les entreprises, ils sont souvent perçus comme
des “boites-noires” par les utilisateurs confrontés à leurs décisions. Ce
constat ne va qu’en s’amplifiant avec le déploiement continu de solutions à
base d’apprentissage machine, dont les dernières avancées techniques
(réseaux de neurones profonds) fournissent des décisions qui sont
inexplicables par construction.

L’objectif de cet atelier est de questionner ces boites-noires, leur nature,
leur conception, et plus généralement leur impact sur leurs usagers et sur la
société. La visée pluridisciplinaire et transversale de l’atelier cherchera
par exemple à aborder des sujets tels que:

– Les biais de traitement des algorithmes, et les moyens de quantifier ce biais?
– L’implémentabilité de la notion de bien commun ?
– Quels outils et quelles métriques pour un audit citoyen des algorithmes ?
– Quelle responsabilité pour les concepteurs d’algorithmes opaques ?
– Les moyens pour l’utilisateur d’observer et d’appréhender les résultats des
algorithmes en boite-noire pour construire une compréhension.
– L’évolution de la société face au nombre grandissant de boites-noires à
visées décisionnelles automatiques, et le manque avéré d’explications des
décisions.
– Quelles notions d’éthique dans le développement courant de ces
boites-noires? Sont elles suffisantes et satisfaisantes ?
– Le traitement des données personnelles des utilisateurs, la notion de
consentement et celle de la compréhension. Comment exercer un contrôle
critique sur le traitement de nos données critiques ?

Intervenants (confirmés):
* Dominique CARDON (sociologue, directeur du Médialab de Sciences Po)
* Loup CELLARD (designer, doctorant au Centre for Interdisciplinary
Methodologies de l’University of Warwick, UK)
* Claude KIRCHNER (directeur de recherches émérite d’Inria, membre de
plusieurs comités liés à l’éthique)
* Claire MATHIEU (directrice de recherches CNRS, spécialiste des algorithmes
et chargée de mission Parcoursup)
* Antoinette ROUVROY (Juriste et philosophe du droit, professeure à
l’université de Namur et chercheuse au FNRS, Belgique)
* Félix TREGUER (membre de la Quadrature du Net et chercheur au Centre
Internet et Société du CNRS et au CERI de Sciences Po)

Le programme courant est disponible ici :
http://atelier-blackbox.conf.citi-lab.fr

Localisation :  Les Halles du Faubourg – 10 Impasse des Chalets, 69007 Lyon

Inscription (gratuite) : http://atelier-blackbox.conf.citi-lab.fr/inscription/


CITI Seminar of Julie Dumas (Université Grenoble Alpes) on May 21 at 11am

Title: Cohérence de caches dans les architectures manycores et simulation

Date and Place: 21 / 05 / 2019 11:00 in TD-C

Host: Guillaume Salagnac

Abstract:

Les besoins en calcul toujours plus important ainsi que la prise en compte de l’efficacité énergétique ont conduit au développement des architectures manycores dont les travaux de recherche sont nombreux et en particulier autour du modèle mémoire. Si nous considérons les machines à mémoire partagée, le passage à l’échelle des protocoles de cohérence de caches est un problème encore ouvert. En effet, les protocoles basés sur l’espionnage, qui doivent transmettre à tous les caches les informations de cohérence, engendrent un nombre important de messages dont peu sont effectivement utiles. En revanche, les protocoles avec répertoires visent à n’envoyer des messages qu’aux caches qui en ont besoin. Dans ce cas, lorsque l’on augmente le nombre de cœurs, la taille du répertoire augmente en largeur et en profondeur et peut même dépasser la taille des données présentent dans les caches. Pour passer à l’échelle, un protocole doit émettre un nombre raisonnable de messages de cohérence et limiter le matériel utilisé pour la cohérence et en particulier pour la mémorisation du répertoire. Dans cette présentation, nous parlerons de DCC (Dynamic Coherent Cluster), une représentation dynamique de la liste des copies pour la cohérence de caches. Dans un second temps, nous nous intéresserons à la simulation de ces architectures qui freinent leur développement. En effet, plus un simulateur est précis plus les temps de simulation sont importants. Une des raisons est que la grande majorité des simulateurs ne s’exécutent pas en parallèle, ainsi une simulation de N cœurs est faite sur un seul cœur physique. Afin d’évaluer rapidement une architecture, nous proposerons un modèle de cache à haut niveau d’abstraction dans lequel des traces provenant d’un simulateur précis (gem5) sont injectées. DCC et d’autres représentations de la liste des copies seront évaluées à l’aide de cette méthodologie.

Biography:
Julie Dumas a obtenu sa thèse de doctorat en informatique à l’Université Grenoble Alpes en 2017. Ses travaux de recherche s’articulent autour de l’architecture des ordinateurs et plus particulièrement à la gestion de la mémoire dans les architectures de type manycores ainsi qu’aux techniques de simulation de ces dernières.


CITI Seminar of Thomas Begin (LIP, UCBL Lyon 1) on April 2 at 11am

Title: Contributions to the Performance Modeling of Computer Networks
Date and Place: 02 / 04 / 2019 11:00 in TD-C
Host: Jean-Marie Gorce and Florent de Dinechin
Abstract:
In this talk, I will present some of my contributions to the fields of performance evaluation and computer networks. I will first discuss a new modeling framework to evaluate the performance of DPDK-based virtual switches in the context of NFV (Network Function Virtualization) networks. Then, I’ll describe a scalable stochastic model to accurately forecast the performance of an IEEE 802.11-based network. Finally, I will introduce an original reduced-state description for multiserver queues that breaks the combinatorial complexity inherent to the classical state description and that can easily handle examples with hundreds of servers.

 

Biography:
Thomas Begin received his Ph.D. degree in Computer Science from UPMC (U. Paris 6) 2008. He was a post-doctoral fellow at UC Santa Cruz in 2009. Since 2009, he is an Associate Professor at UCBL (U. Lyon 1) in the Computer Science department. During the 2015-2016 academic year, he was on research leave at DIVA lab – University of Ottawa. T. Begin research interests are in performance evaluation, future network architecture, and system modeling. His principal applications pertain to high-level modeling, wireless networks, resource allocation and queueing systems.

CITI Seminar of Eddy Caron (LIP, École Normale Supérieure de Lyon) on March 19 at 11am

Title: Once upon a time … the deployment
Date and Place: 19/03/ 2019 11:00 in TD-C
Host: Jean-Marie Gorce and Florent de Dinechin
Abstract:
In large distributed systems the resource managements is one key of the efficient. And the deployment of the elements on resources are hidden everywhere, across the network, across the virtualization, across many infrastructures, etc. Through 6 stories we will discover many points of view of the deployment. First adventure, we will see how to deploy a middleware with self-stabilization skill. In the second story, be afraid, we will see how to deploy a secure Cloud Infrastructure. In the following story, we will introduce a deployment tool for reproducibility. The licenses deployment is another weird story with a lot of mysteries. An unbelievable story to deploy a data-driven microservices infrastructure. And finally, we will try to clear up the Fog deployment.

 

Biography:
Eddy Caron is an Associate Professor at Ecole Normale Supérieure de Lyon and holds a position with the LIP laboratory (ENS Lyon, France). He is a member of AVALON project from INRIA and Technical Manager for the DIET software package. He received his PhD in C.S. from University de Picardie Jules Verne in 2000 and his HDR (Habilitation à Diriger les Recherches) from the Ecole Normale Supérieure de Lyon in 2010. His research focuses on distributed computing environment, from P2P to Grid, Cloud and Edge computing. At the middleware level, he deals with a large scope of subjects (scheduling, workflow management, data management, energy management, security, software management, etc.)  with the same point of view of the resource magement in heterogeneous environments.
He is involved in many program committees (as HCW, IPDPS, ISPA, CloudTech, etc.). Since 2000, he contributed to more than 30 articles in journal or book chapter and more than 80 publications in international conferences. He was co-chair of the GridRPC working group in OGF. He was coordinator of two french ANR project (LEGO and SPADES). He was workpackage leader in the European project Seed4C around the security. He is the supervisor of 15 Phd (4 in progress). He teaches Distributed system, Architecture Operating System and Network, Grid and Cloud, etc. Moreover he was the Co-funder and Scientific Consultant of a company (SysFera). Deputy Director in charge of call for projects, research transfert and international affairs for the LIP Laboratory.  See http://graal.ens-lyon.fr/~ecaron for further information.