Jeudi 6 Octobre

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Jeudi 6 Octobre
Heure: 10:30 - 11:30
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Solving the Asymmetric Travelling Salesman Problem
Description: Luis Gouveia There are many ways of modelling the Asymmetric Traveling Salesman Problem (ATSP) and the related Precedence Constrained ATSP (PCATSP).
In this talk we present new formulations for the two problems that can be viewed as resulting from combining precedence variable based formulations, with network flow based formulations. As suggested in [1], the former class of formulations permits to integrate linear ordering constraints.
The motivating formulation for this work is a complicated and "ugly" formulation that results from
the separation of generalized subtour elimination constraints presented in [2] (see also [1]).
This so called "ugly" formulation exhibits, however, one interesting feature, namely the "disjoint subpaths" property that is further explored to create more complicated formulations that combine two (or three) "disjoint path" network flow based formulations and have a stronger linear programming bound.
Some of these stronger formulations are related to the ones presented for the PCATSP in [3] and can be viewed as generalizations in the space of the precedence based variables.
Several sets of projected inequalities in the space of the arc and precedence variables and in the spirit of many presented in [1] are obtained by projection from these network flow based formulations.
Computational results will be given for the ATSP and PCATSP to evaluate the quality of the new
models and inequalities.
[1] L. Gouveia and P. Pesneau. On extended formulations for the precedence constrainted asymmetric
traveling salesman problem. Networks, 48(2):77{89, 2006.
[2] L. Gouveia and J. M. Pires. The asymmetric travelling salesman problem: On generalizations of
disaggregated Miller-Tucker-Zemlin constraints. Discrete Applied Mathematics, 112:129{145, 2001.

Joint work with Pierre Pesneau (University of Bordeaux), Mario Ruthmair (University of Vienna) and Daniel Santos (University of Lisbon)
Heure: 13:00 - 15:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Automatic Extraction of Malicious Behaviors
Description: Khanh-Huu-The Dam
The number of new malwares is increasing everyday.
Thus malware detection is nowadays a big challenge. The
existing techniques for malware detection require a huge
effort of engineering to manually extract the malicious behaviors.
To avoid this tedious task, we propose in this paper
an approach to automatically extract the malicious behaviors.
We model a program using an API call graph,
and we represent the malicious behaviors using a malicious
API graph. We then reduce the malicious behavior extraction
problem to the problem of retrieving from the benign
and malicious API call graphs the set of subgraphs that
are relevant for malicious behaviors. We solve this issue
by applying and adapting well-known efficient Information
Retrieval techniques based on the TFIDF scheme. We use
our automatically extracted malicious behavior specification
for malware detection using a kind of product between
graphs. We obtained interesting experimental results, as we
get 99.04% of detection rate. Moreover, we were able to
detect several malwares that well-known and widely used
antiviruses such as Panda, Avira, Kaspersky, Avast, Qihoo-
360, McAfee, AVG, BitDefender, ESET-NOD32, F-Secure,
and Symantec could not detect.

This is a joint work with Tayssir Touili.
Heure: 14:00 - 17:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Évaluation multi-précision rigoureuse de fonctions D-finies
Description: Marc Mezzarobba