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News
- Journée au vert POLARIS 2022/05/23
- DATAMOVE/POLARIS picnic 2021/06/22
- DATAMOVE/POLARIS BBQ 2019 2019/06/14
- POLARIS Bootcamp (May 2019) 2019/05/24
- slides of Andras Gyorgy 2016/01/15
Next seminars
Events
Events in June–July 2017
MMonday TTuesday WWednesday TThursday FFriday SSaturday SSunday 29May 29, 201730May 30, 201731May 31, 2017Keynote LIG (Antoine Cornuéjols)
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June 1, 2017Bâtiment IMAG (amphitheater)Saint-Martin-d'Hères, 38400France2June 2, 20173June 3, 20174June 4, 20175June 5, 20176June 6, 20177June 7, 20179June 9, 201710June 10, 201711June 11, 201712June 12, 201713June 13, 201714June 14, 2017Coalition games on interaction graphs by Nicolas Bousquet (Gscop)
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June 15, 2017We consider cooperative games where the viability of a coalition is determined by whether or not its members have the ability to communicate amongst themselves. This necessary condition for viability was proposed by Myerson and is modeled via an interaction graph; a coalition S of vertices is then viable if and only if the induced graph S is connected.
The non-emptiness of the core of a coalition game can be tested by a well-known covering LP. Moreover, the integrality gap of its dual packing LP defines exactly the multiplicative least-core and the relative cost of stability of the coalition game. This gap is upper bounded by the packing-covering ratio which is known to be at most the treewidth of the interaction graph plus one.
We examine the packing-covering ratio and integrality gaps of graphical coalition games in more detail. First we introduce a new graph parameter, called the vinewidth (a parameter derived from the treewidth), which characterizes the worst packing-covering ratio. Then we will show that this new parameter correctly evaluates both primal and dual integrality gaps.
Joint work with Zhentao Li and Adrian Vetta.
Bâtiment IMAG (442)16June 16, 201717June 17, 201718June 18, 201719June 19, 201720June 20, 201721June 21, 2017Malcom Egan Seminar : "Mechanism design in on-demand transport"
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June 22, 2017Abstract: Uber is one of several recent companies adopting a business model that lies in stark contrast with the standard approach used by taxi services. Underlying Uber's business model is a new architecture--based on a market mechanism--which governs how commuters, drivers, and the company interact with each other. In this talk, we develop a new general model for on-demand transport networks with self-interested passengers and drivers. With this model, we introduce market mechanisms to allocate and price journeys, as well as the market formation subproblem. By analysis and simulation, we characterize the performance of the mechanisms and discuss insights using data obtained from a real on-demand transport provider.
Malcolm Egan received the B.E. degree in electrical engineering from the University of Queensland, Brisbane, Australia, in 2009 and the Ph.D. in electrical engineering from the University of Sydney, Sydney, Australia, in 2014. In the years 2014-2016, he was a Postdoctoral Researcher in the Department of Computer Science, Czech Technical University in Prague, Czech Republic and in the Laboratoire de Mathématiques, Université Blaise Pascal, Clermont-Ferrand, France. He is now a Postdoctoral Researcher in CITI Lab, INSA-Lyon, INRIA, Université de Lyon. His research interests include optimization theory, mechanism design, information theory and statistical signal processing, as well as their applications.
Bâtiment IMAG (442)23June 23, 201724June 24, 201725June 25, 201726June 26, 201727June 27, 201728June 28, 2017A stochastic approach for optimizing green energy consumption in distributed clouds by Fanny Dufossé (Inria)
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June 29, 2017A stochastic approach for optimizing green energy consumption in distributed clouds
The energy drawn by Cloud data centers is reaching worrying levels, thus inciting providers to install on-site green energy producers, such as photovoltaic panels. Considering distributed Clouds, workload managers need to geographically allocate virtual machines according to the green production in order not to waste energy. In this paper, we propose SAGITTA: a Stochastic Approach for Green consumption In disTributed daTA centers. We show that compared to the optimal solution, SAGITTA consumes 4% more brown energy, and wastes only 3.14% of the available green energy, while a traditional round-robin solution consumes 14.4% more energy overall than optimum, and wastes 28.83% of the available green energy.
Bâtiment IMAG (442)30June 30, 2017July
1July 1, 20172July 2, 20173July 3, 20174July 4, 20175July 5, 2017Séminaire Josu Doncel : Under-Approximation Computation Through Optimal Control
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July 6, 2017Title: Under-Approximation Computation Through Optimal Control
Abstract: Under-approximation provides a subset of the reachable set of an uncertain dynamical system which can then be used to formally falsify properties of quantitative models. Using Pontryagin’s principle, our approach computes an under-approximation for a linear combination of state variables of nonlinear ordinary differential equations and time-varying uncertainties. By a numerical comparison against state-of-the-art tools Flow^∗ and CORA, we show that our methodology provides tight under-approximations in benchmarks, and that it can scale to models that are out of reach with these over-approximation techniques.
Bâtiment IMAG (442)I/O performance for HPC: finding the right access pattern and avoiding interference by Francieli Zanon-Boito
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July 6, 2017Title:
I/O performance for HPC: finding the right access pattern and avoiding interferenceAbstract:
Scientific applications are executed in a high performance computing (HPC) environment, where a parallel file system (PFS) provides access to a shared storage infrastructure. The key characteristic of these systems is the use of multiple storage servers, from where data can be obtained by the clients in parallel. The performance observed by applications when accessing a PFS is directly affected by the way they perform this access, i.e. their access pattern.
In this seminar, I'll discuss my work with the Ondes3D seismic simulation, which was focused into changing the application's access pattern to improve I/O performance without changing the output format. Moreover, I'll discuss my previous and current work on I/O scheduling at different levels of the I/O stack, pointing current challenges for future work.Bâtiment IMAG (442)7July 7, 20178July 8, 20179July 9, 201710July 10, 201711July 11, 201712July 12, 201713July 13, 201714July 14, 201715July 15, 201716July 16, 201717July 17, 201718July 18, 201719July 19, 201720July 20, 201721July 21, 201722July 22, 201723July 23, 201724July 24, 201725July 25, 201726July 26, 201727July 27, 201728July 28, 201729July 29, 201730July 30, 2017Meta
Performance evaluation and Optimization of LARge Infrastructures and Systems
