International Professional University of Technology in Nagoya Repository
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Graphes expanseurs et crible dans les structures combinatoires
No full textInternational audienceWe prove a general large sieve statement in the context of random walks on subgraphs of a given graph. This can be seen as a generalization of previously known results where one performs a random walk on a group enjoying a strong spectral gap property. In such a context the point is to exhibit a strong uniform expansion property for a suitable family of Cayley graphs on quotients. In our combinatorial approach, this is replaced by a result of Alon--Roichman about expanding properties of random Cayley graphs. Applying the general setting we show e.g., that with high probability (in a strong explicit sense) random coloured subsets of integers contain monochromatic (non-empty) subsets summing to zero, or that a random coloring of the edges of a complete graph contains a monochromatic triangle
Computational pan-genomics: status, promises and challenges
No full textInternational audienceMany disciplines, from human genetics and oncology to plant breeding, microbiology and virology, commonly face the challenge of analyzing rapidly increasing numbers of genomes. In case of Homo sapiens, the number of sequenced genomes will approach hundreds of thousands in the next few years. Simply scaling up established bioinformatics pipelines will not be sufficient for leveraging the full potential of such rich genomic data sets. Instead, novel, qualitatively different computational methods and paradigms are needed. We will witness the rapid extension of computational pan-genomics, a new sub-area of research in computational biology. In this article, we generalize existing definitions and understand a pan-genome as any collection of genomic sequences to be analyzed jointly or to be used as a reference. We examine already available approaches to construct and use pan-genomes, discuss the potential benefits of future technologies and methodologies and review open challenges from the vantage point of the above-mentioned biological disciplines. As a prominent example for a computational paradigm shift, we particularly highlight the transition from the representation of reference genomes as strings to representations as graphs. We outline how this and other challenges from different application domains translate into common computational problems, point out relevant bioinformatics techniques and identify open problems in computer science. With this review, we aim to increase awareness that a joint approach to computational pan-genomics can help address many of the problems currently faced in various domains
A Modal Separation Logic for Resource Dynamics
No full textInternational audienceThe logic of Bunched implications (BI), and its boolean version (Boolean BI), are logics that allow us to express properties on resources and to provide logical frameworks for the so-called separation logics. In this paper we study a new modal separation logic that extends Boolean BI with two kinds of modalities, in order to deal with resources having dynamic properties (which depend on the current state of a system) and also to capture some resource evolutions or transformations. We show how we can model concurrent processes manipulating resources, and we provide a sound and complete tableau calculus, with a counter-model extraction method, for proving properties expressed in this logic
Combining Traffic Shaping Methods with Congestion Control Variants for HTTP Adaptive Streaming
No full textInternational audienceHTTP adaptive streaming (HAS) is a streaming video technique widely used over the Internet. However, it has many drawbacks that degrade its user quality of experience (QoE). Our investigation involves several HAS clients competing for bandwidth inside the same home network. Studies have shown that managing the bandwidth between HAS clients using traffic shaping methods improves the QoE. Additionally, the TCP congestion control algorithm in the HAS server may also impact the QoE because every congestion control variant has its own method to control the congestion window size. Based on previous work, we describe two traffic shaping methods, the Hierarchical Token Bucket shaping Method (HTBM) and the Receive Window Tuning Method (RWTM), as well as four popular congestion control variants: NewReno, Vegas, Illinois, and Cubic. In this paper, our objective is to provide a detailed comparative evaluation of combining these four congestion control variants with these two shaping methods. The main result indicates that Illinois with RWTM offers the best QoE without causing congestion. Results were validated through experimentation and objective QoE analytical criteria
High dimensional Hawkes processes for limit order books Modelling, empirical analysis and numerical calibration
No full textInternational audienceHigh-dimensional Hawkes processes with exponential kernels are used to describe limit order books in order-driven financial markets. The dependencies between orders of various types are carefully studied and modelled, based on a thorough empirical analysis. The observation of inhibition effects is particularly interesting, and leads us to the use of non-linear Hawkes processes. A specific attention is devoted to the calibration problem, in order to account for the high dimensionality of the problem and the very poor convexity properties of the MLE. Our analyses show a good agreement between the statistical properties of order book data and those of the model
La méthodologie Radical Innovation Design® (en bref, positionnement pour les experts de l’innovation)
No full textLa méthodologie Radical Innovation Design (RID) est développée depuis 10 ans à CentraleSupélec. C'est une approche intégrée d'innovation radicale « tirée » par les usages insatisfaisants/problématiques qui se différencie significativement des méthodes classiques comme Design Thinking, théorie CK, TRIZ, Business Model Canvas, Lean Startup, Stratégie Océan Bleu. RID propose une terminologie, des concepts, un processus, des algorithmes et des outils originaux qui seront présentés au travers d'exemples industriels. Une étude RID part d'un champ d'activités (ou d'usages) qu'il s'agit d'explorer systématiquement pour bien poser le problème. La convergence vers un concept innovant se fait par exploration systématique du problème et des opportunités..
A unified approach for the -stability analysis of classical and fractional neutral systems with commensurate delays
No full textInternational audienceWe examine the stability of linear integer-order and fractional-order systems with commensurate delays of neutral type in the sense of -stability. The systems may have chains of poles approaching the imaginary axis. While several classes of these systems have been previously studied on a case-by-case basis, a unified method is proposed in this paper which allows to deal with all these classes at the same time. Approximation of poles of large modulus is systematically calculated based on a convex hull derived from the coefficients of the system. This convex hull also serves to establish sufficient conditions for instability and necessary and sufficient conditions for stability
SELP: Semi-supervised evidential label propagation algorithm for graph data clustering
No full textInternational audienceWith the increasing size of social networks in the real world, community detection approaches should be fast and accurate. The label propagation algorithm is known to be one of the near-linear solutions which is easy to implement. However, it is not stable and it cannot take advantage of the prior information about the network structure which is very common in real applications. In this paper, a new Semi-supervised clustering approach based on an Evidential Label Propagation strategy (SELP) is proposed to incorporate limited domain knowledge into the community detection model. The main advantage of SELP is that it can effectively use limited supervised information to guide the detection process. The prior information about the labels of nodes in the graph, including the labeled nodes and the unlabeled ones, is initially expressed in the form of mass functions. Then the evidential label propagation rule is designed to propagate the labels from the labeled nodes to the unlabeled ones. The communities of each node can be identified after the propagation process becomes stable. The outliers can be identified to be in a special class. Experimental results demonstrate the effectiveness of SELP on both graphs and classical data sets
Editorial Message Track on Software-intensive Systems-of-Systems (SiSoS) of the 33rd ACM/SIGAPP Symposium On Applied Computing (SAC 2018)
No full textInternational audiencePervasiveness of networks has made possible to interconnect systems that were independently developed, operated, managed, and evolved, yielding a new kind of complex system, i.e. a system that is itself composed of systems, the so-called System-of-Systems (SoS). Software-intensive SoS (SiSoS) has become a hotspot in the last years, from both the research and industry viewpoints. Indeed, various aspects of our lives and livelihoods have progressively become dependent on some sort of Software-intensive SoS. This is the case of SiSoS found in different areas as diverse as energy, healthcare, manufacturing, and transportation; and applications that address societal needs, e.g. environmental monitoring, distributed energy grids, emergency coordination, global traffic control, and smart cities. Moreover, ubiquitous platforms such as the Internet of Things and nascent kinds of SoS such as Cyber-Physical SoSs are accelerating the deployment of Software-intensive SoS in the near future. Definitely, the unique characteristics of Software-intensive SoS raise a grand research challenge for the future of software-reliant systems in our industry and society due to its intrinsic features, among which evolutionary development and emergent behavior. Statistics The SiSoS Track received 22 regular paper submissions and 3 SRC submissions. Each submission was reviewed by three members of the Track Program Committee. The Track Program Committee selected 5 full papers out of the 22, giving an acceptance rate of 23%. These papers were selected based on originality, quality, soundness, and relevance to this conference track. Moreover, 2 poster papers have been accepted for publications in the proceedings of the conference. Key Topics This track fosters (but is not limited to) submissions in the following topics
PDB-wide identification of biological assemblies from conserved quaternary structure geometry
No full textInternational audienceProtein structures are key to understanding bio-molecular mechanisms and diseases, yet their interpretation is hampered by limited knowledge of their biologically relevant quaternary structures (QSs). A critical challenge in obtaining QSs from crystallographic data is to distinguish biological interfaces from crystal packing contacts. We tackled this challenge with two strategies for aligning and comparing QS states, both across homologs (QSalign), and across data repositories (QSbio). QS conservation across homologs was a remarkably strong predictor of biological relevance and allowed annotating of >80,000 biological QS states. QS conservation across methods enabled us to create a meta-predictor, QSbio, from which we inferred confidence estimates for >110,000 assemblies in the Protein Data Bank, which approach the accuracy of manual curation. Based on the dataset obtained, we analyzed interaction interfaces among pairs of structurally conserved QSs. This revealed a striking plasticity of interfaces, which can maintain a similar interaction geometry through widely different chemical properties