Mardi 5 Mai
Heure: 
14:00  17:00 
Lieu: 
Salle B107, bâtiment B, Université de Villetaneuse 
Résumé: 
Comptage et énumération de surfaces plates, formes quasimodulaires 
Description: 
Samuel Lelièvre 
Jeudi 7 Mai
Heure: 
15:00  18:00 
Lieu: 
Salle B107, bâtiment B, Université de Villetaneuse 
Résumé: 
Présoutenance de thèse : A left/right dynamic on permutations 
Description: 
Quentin de Mourgues Soit s une permutation dans Sigma_n.Soit i(s)=s(1), j(s)=s^{1}(1),Soit C_k le cycle 1>2>...>(k1)>1 (k,k+1,..,n points fixes).On definit L et R comme suit:L(s) = C_{j(s)}.s etR(s) = s.C_{i(s)}^{1}Il est facile de voir que L et R sont inversibles, la dynamique L/R partitionne donc Sigma_n en classes d'équivalence qui sont des graphes orientés uniformes (une arête entrant/sortant par "couleur" L et R) fortement connexes.Dans cet exposé, on étudiera ces classes : leur nombre, leur taille, leur structure, etc. 
Heure: 
16:00  19:00 
Lieu: 
Salle B107, bâtiment B, Université de Villetaneuse 
Résumé: 
Présoutenance de thèse : Tilings 
Description: 
Alexandra Ugolnikova 
Lundi 11 Mai
Heure: 
14:00  15:00 
Lieu: 
Salle B107, bâtiment B, Université de Villetaneuse 
Résumé: 
Structured Prediction, Optimization and Deep Syntax 
Description: 
Caio Filippo Corro A sequence of words is not a sufficient representation for efficient processing of natural languages. In order to extract information from sentences, we need to decode their underlying abstract structure(s). Unfortunately, grammar formalisms that are able to properly capture complicated phenomena encountered in natural languages (whmovements, crossserial dependencies,...) have a repelling complexity. The work in this thesis will focus on developing efficient parsing algorithms for various formalisms (TAG, LCFRS, RCG) using optimization methods (Lagrangian relaxation, dual decomposition). 
Mardi 12 Mai
Heure: 
11:00  14:00 
Lieu: 
Salle B107, bâtiment B, Université de Villetaneuse 
Résumé: 
Various aspects of automaton synchronization 
Description: 
Mikhael Berlinkov 
Heure: 
12:30  13:30 
Lieu: 
Salle B107, bâtiment B, Université de Villetaneuse 
Résumé: 
EXACT APPROACHES TO THE NETWORK DESIGN PROBLEM WITH RELAYS 
Description: 
Ivana Ljubic This work considers the Network Design Problem with Relays (NDPR). The NDPR arises in the context of network design when given nodepairs need to communicate with each other, but, due to signal deterioration, communication paths have to respect given distance limits. To cover longer distances, equipment for signal regeneration (i.e., relays) may be required. To enable required communications, one has to upgrade the network: by installing new links, by installing relays on the existing network, or by a combination of both. Besides applications in network design, the NDPR arises in the context of emobility where relays model charging stations for electric cars and edge costs correspond to road tolls.
In contrast to previous work on the NDPR, which was mainly focused on heuristic approaches, we propose new exact approaches based on different mixed integer linear programming formulations for the problem. We develop BranchandPrice and BranchPriceandCut algorithms that build upon models with an exponential number of constraints and variables. In a computational study, we analyze the performance of these approaches for instances with different characteristics.
This is a joint work with M. Leitner, M. Riedler and M. Ruthmair 
Heure: 
14:00  17:00 
Lieu: 
Salle B107, bâtiment B, Université de Villetaneuse 
Résumé: 
Énumération d'automates minimaux et fonctions de parking 
Description: 
JeanBaptiste Priez 
Mardi 19 Mai
Heure: 
12:30  13:30 
Lieu: 
Salle B107, bâtiment B, Université de Villetaneuse 
Résumé: 
Approximating the energy storage problem and other continuous dynamic programs 
Description: 
Giacomo Nannicini We study the problem of optimally managing a source of renewable energy connected to the power grid, a battery, and potentially a household or some other form of energy sink. This problem can be naturally cast as a dynamic program. We propose a model for this problem that subsumes other models in the literature, and we analyze its complexity, showing that in the deterministic setting the problem is solvable in polynomial time, but it becomes #Phard in the stochastic setting. A variant of the problem that is commonly encountered in practice (i.e. the one where selling energy to the power grid is not allowed) admits a Fully Polynomial Time Approximation Scheme (FPTAS) if the energy levels are discretized; but what about the more natural case where energy is considered a continuous variable? We show that in this case, the problem belongs to a class of convex continuous dynamic programs that admits neither a multiplicative nor an additive approximation. We then show that we can construct a novel type of approximation scheme, where additive and multiplicative approximation are required at the same time but both can be arbitrarily small. We discuss a preliminary computational evaluation of this new type of approximation scheme for continuous convex dynamic programs, showing its potential. 
Heure: 
14:00  17:00 
Lieu: 
Salle B107, bâtiment B, Université de Villetaneuse 
Résumé: 
Explicit forms and combinatorial content of Levy stable distributions 
Description: 
Katarzyna Górska 
Jeudi 21 Mai
Heure: 
14:30  15:30 
Lieu: 
Salle B107, bâtiment B, Université de Villetaneuse 
Résumé: 
Reachability Preservation Based Parameter Synthesis for Timed Automata 
Description: 
Étienne André The synthesis of timing parameters consists in deriving conditions on the timing constants of a concurrent system such that it meets its specification. Parametric timed automata are a powerful formalism for parameter synthesis, although most problems are undecidable. We first address here the following reachability preservation problem: given a reference parameter valuation and a (bad) control state, do there exist other parameter valuations that reach this control state iff the reference parameter valuation does? We show that this problem is undecidable, and introduce a procedure that outputs a possibly underapproximated answer. We then show that our procedure can efficiently replace the behavioral cartography to partition a bounded parameter subspace into good and bad subparts; furthermore, our procedure can even outperform the classical badstate driven parameter synthesis semialgorithm, especially when distributed on a cluster. 
Mardi 26 Mai
Heure: 
14:00  17:00 
Lieu: 
Salle B107, bâtiment B, Université de Villetaneuse 
Résumé: 
Efficient Algebraic Diagonals and Walks 
Description: 
Louis Dumont The diagonal of a multivariate power series F is the univariate power series Diag F generated by the diagonal terms of F. Diagonals form an important class of power series; they occur frequently in number theory, theoretical physics and enumerative combinatorics. Westudy algorithmic questions related to diagonals in the case where F is the Taylor expansion of a bivariate rational function. It is classical that in this case Diag F is an algebraic function. We propose an algorithm that computes an annihilating polynomial forDiag F. Generically, it is its minimal polynomial and is obtained in time quasilinear in its size. We show that this minimal polynomial has an exponential size with respect to the degree of the input rational function. Throughout the talk, we use a common problemof counting certain lattice walks to illustrate the capacities and limits of our tools. 
Mercredi 27 Mai
Heure: 
14:00  16:00 
Lieu: 
Salle B107, bâtiment B, Université de Villetaneuse 
Résumé: 
Logics via algebras and substitutions 
Description: 
Antonino Salibra In this talk we present a translation of formulas and models of classical and nonclassical logics into factor algebras. The correspondence: Propositional variables  operator of decompositions Logical operations  substitutions Formulas  algebraic terms Models  factor algebras, provides a uniform calculus of provability for all the logics which admit the translation. Many examples will be discussed: classical logic, intuitionistic logic, linear logic, manyvalued logics. 

