Dissertations / Theses on the topic 'Graphons de probabilités'
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Weibel, Julien. "Graphons de probabilités, limites de graphes pondérés aléatoires et chaînes de Markov branchantes cachées." Electronic Thesis or Diss., Orléans, 2024. http://www.theses.fr/2024ORLE1031.
Full textGraphs are mathematical objects used to model all kinds of networks, such as electrical networks, communication networks, and social networks. Formally, a graph consists of a set of vertices and a set of edges connecting pairs of vertices. The vertices represent, for example, individuals, while the edges represent the interactions between these individuals. In the case of a weighted graph, each edge has a weight or a decoration that can model a distance, an interaction intensity, or a resistance. Modeling real-world networks often involves large graphs with a large number of vertices and edges.The first part of this thesis is dedicated to introducing and studying the properties of the limit objects of large weighted graphs : probability-graphons. These objects are a generalization of graphons introduced and studied by Lovász and his co-authors in the case of unweighted graphs. Starting from a distance that induces the weak topology on measures, we define a cut distance on probability-graphons. We exhibit a tightness criterion for probability-graphons related to relative compactness in the cut distance. Finally, we prove that this topology coincides with the topology induced by the convergence in distribution of the sampled subgraphs. In the second part of this thesis, we focus on hidden Markov models indexed by trees. We show the strong consistency and asymptotic normality of the maximum likelihood estimator for these models under standard assumptions. We prove an ergodic theorem for branching Markov chains indexed by trees with general shapes. Finally, we show that for a stationary and reversible chain, the line graph is the tree shape that induces the minimal variance for the empirical mean estimator among trees with a given number of vertices
Selig, Thomas. "Convergence de cartes et tas de sable." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0286/document.
Full textThis Thesis studies various problems located at the boundary between Combinatorics and Probability Theory. It is formed of two independent parts. In the first part, we study the asymptotic properties of some families of \maps" (from a non traditional viewpoint). In thesecond part, we introduce and study a natural stochastic extension of the so-called Sandpile Model, which is a dynamic process on a graph. While these parts are independent, they exploit the same thrust, which is the many interactions between Combinatorics and Discrete Probability, with these two areas being of mutual benefit to each other. Chapter 1 is a general introduction to such interactions, and states the main results of this Thesis. Chapter 2 is an introduction to the convergence of random maps. The main contributions of this Thesis can be found in Chapters 3, 4 (for the convergence of maps) and 5 (for the Stochastic Sandpile model)
Budzinski, Thomas. "Cartes aléatoires hyperboliques." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS426/document.
Full textThis thesis falls into the theory of random planar maps, which has been active in the last fifteen years, and more precisely into the study of hyperbolic models.We are first interested in a model of dynamical random triangulations based on edge-flips, where we prove a lower bound on the mixing time.In the rest of this thesis, the main objects that we study are the random hyperbolic triangulations called PSHT. These are hyperbolic variants of the Uniform Infinite Planar Triangulation (UIPT), and were introduced by Nicolas Curien in 2014. We first establish a near-critical scaling limit result: if we let the hyperbolicity parameter go to its critical value at the same time as the distances are renormalized, the PSHT converge to a random metric space that we call the hyperbolic Brownian plane. We also study precise metric properties of the PSHT and of the hyperbolic Brownian plane, such as the structure of their infinite geodesics. We obtain as well new properties of the Poisson boundary of the PSHT.Finally, we are interested in another natural model of hyperbolic random maps: supercritical causal maps, which are obtained from supercritical Galton--Watson trees by adding edges between vertices at the same height. We establish metric hyperbolicity results about these maps, as well as properties of the simple random walk (including a positive speed result). Some of the properties we obtain are robust, and may be generalized to any planar map containing a supercritical Galton--Watson tree
Ravelomanana, Vlady. "Graphes multicycliques étiquetés : aspects combinatoires et probabilistes." Amiens, 2000. http://www.theses.fr/2000AMIE0122.
Full textBroutin, Nicolas. "Random trees, graphs and recursive partitions." Habilitation à diriger des recherches, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00842019.
Full textArbres aléatoires uniformes. Il s'agit ici de mieux comprendre un objet limite essentiel, l'arbre continu brownien (CRT). Je présente quelques résultats de convergence pour des modèles combinatoires ''non-branchants'' tels que des arbres sujets aux symétries et les arbres à distribution de degrés fixée. Je décris enfin une nouvelle décomposition du CRT basée sur une destruction partielle.
Graphes aléatoires. J'y décris la construction algorithmique de la limite d'échel-le des graphes aléatoires du modèle d'Erdös--Rényi dans la zone critique, et je fais le lien avec le CRT et donne des constructions de l'espace métrique limite. Arbres couvrant minimaux. J'y montre qu'une connection avec les graphes aléatoires permet de quantifier les distances dans un arbre convrant aléatoire. On obtient non seulement l'ordre de grandeur de l'espérance du diamètre, mais aussi la limite d'échelle en tant qu'espace métrique mesuré. Partitions récursives. Sur deux exemples, les arbres cadrant et les laminations du disque, je montre que des idées basées sur des théorèmes de point fixe conduisent à des convergences de processus, où les limites sont inhabituelles, et caractérisées par des décompositions récursives.
El, Maftouhi Abdelhakim. "Méthodes probabilistes en combinatoire et théorie des graphes." Paris 11, 1994. http://www.theses.fr/1994PA112408.
Full textMurat, Cécile. "Les problèmes d'optimisation combinatoire probabilistes dans les graphes." Paris 9, 1997. https://portail.bu.dauphine.fr/fileviewer/index.php?doc=1997PA090054.
Full textPanafieu, Elie de. "Combinatoire analytique des graphes, hypergraphes et graphes inhomogènes." Paris 7, 2014. http://www.theses.fr/2014PA077167.
Full textWe investigate two graph-like models: the non-uniform hypergraphs and the inhomogeneous graphs. They are close to the models defined by Darling and Norris (2004) and Sôderberg (2002). We enumerate them and derive structure information before and near the birth of the giant component. The inhomogeneous graph model proves to be a convenient framework for the modeling of several tractable constraint satisfaction problems (CSP), such as the 2-colorability problem, the satisfiability of 2-Xor formulas and of quantified 2-Xor formulas. We link the probability of satisfiability of those problems to the enumeration of inhomogeneous graphs. As an application, proofs of old and new phase transition results are derived in a unified framework. Finally, we derive a new simple proof for the asymptotic number of connected multigraphs with a number of edges proportional to the number of vertices. This result was first derived for simple graphs by Bender, Canfield and McKay (1990). The main tool of this thesis is analytic combinatorics, as defined by Flajolet and Sedgewick in their book (2009)
Hutchcroft, Thomas. "Discrete probability and the geometry of graphs." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62595.
Full textScience, Faculty of
Mathematics, Department of
Graduate
Mercier, Lucas. "Grands graphes et grands arbres aléatoires : analyse du comportement asymptotique." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0028/document.
Full textThis thesis is dedicated to the study of the asymptotic behavior of some large random graphs and trees. First is studied a random graph model introduced by Bo Söderberg in 2002. One chapter of this manuscript is devoted to the study of the asymptotic behavior of the size of the connected components near the critical window, linking it to the lengths of excursion of a Brownian motion with parabolic drift. The next chapter talks about a random graph process suggested by Itai Benjamini, defined as follows: edges are independently added at a fixe rate. Whenever a vertex reaches degree k, all adjacent edges are removed. This process is non-increasing, preventing the use of some commonly used methods. By using local limits, in the spirit of the PWIT, we were able to prove the presence (resp. absence) of a giant component at some stages of the process when k>=5 (resp. k<=3). In the case k=4, these results allows to link the presence (resp. absence) of a giant component to the supercriticality (resp. criticality or subcriticality) of an associated branching process. In the last chapter, the height of random Lyndon tree is studied, and is proven to be approximately c ln n, in which c=5.092... the solution of an optimization problem. To obtain this result, we couple the Lyndon tree with a Yule tree, then studied with the help of branching walks and large deviations
Launay, Mickaël. "Urnes interagissantes." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4775/document.
Full textWe study the asymptotic behavior of several Polya-type strongly reinforced interacting urns. The main results deal with exponential or exponential-like reinforcements and temporal interactions, that is when the urns interact only at some random times. In that case, we show the existence of a transition of phase depending on the frequency of interactions. If this frequency is larger than 1/2, all the urns eventually fixate on the same color, while if it is smaller than 1/2, a majority color will be fixed after some finite random time but while some of the urns eventually draw only the majority color, there can be other urns that still draw other colors at times where there is no interactions. When the reinforcement becomes infinite, we can calculate the law of the number of urns of later type when the total number of urns is two or an odd integer greater than two.When the interaction is maximal, that is when all the urns interact at any time, we show that a strong and non-decreasing reinforcement, but not necessarily exponential, suffices to obtain the fixation of all the urns on the same color.At the end, we consider briefly the spatial interaction model in which the urns are located on the vertices of a graph and interact only with their neighbors. In that case, we discuss some properties of sub-graphs that can fixate on one color with positive probability
Faÿ, Armelle. "Sur la propagation de l'information dans les réseaux probabilistes." Paris 6, 1997. http://www.theses.fr/1997PA066770.
Full textGaertig-Stahl, Alice. "Modèles probabilistes de feux de forêt sur des graphes infinis." Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1884/.
Full textThis work is concerned with a probabilistic study of forest-fire models. The models studied here were introduced in the context of self-organized criticality at the end of the eighties. These models are systems of particles, the trees, defined on connected graphs. Their evolution is governed by two families of Poisson processes, one for the growth of trees, the other one for the ignition of trees by lightning. The influence of lightning is characterized by a parameter lambda > 0. These models were widely studied on Z. However, only the existence and uniqueness of more general infinitevolume forest-fire processes have been proven yet. In this thesis, we studied forest-fire models on Zd for d > 2 and on binary trees, in two directions. The first one is concerned with the existence of stationary measures. The second one is concerned with the study of these processes when the parameter lambda tends to zero. In the first part, we will show the existence of at least one stationary measure for forest-fire processes on Zd, d > 2, for all parameters lambda > 0. The forest-fire processes are Markov processes but not Feller processes, so the usual arguments cannot be used here. Moreover, the geometry of Zd does not allow using the same arguments as for Z. Tools developed while studying these processes on Zd will be used here. In the second part, we will study the behavior of the forest-fire processes on binary trees when the parameter lambda tends to zero. We will begin with the study of a model without any fires, in order to understand better how the clusters of trees grow. We will show a convergence in law of the number of sites of a set construct from a ball of radius and the intersecting clusters, after a time tn > 0, for processes rescaled in space and time. Then, we will add fires and define a modified forest-fire model. In this new model, apart from the cluster of the origin, the clusters evolve under a stationary measure which we expect at the limit in lambda, and not under the dynamic of the initial forest-fire model. For this model, we will show a convergence in law of the rescaled size of the cluster of the origin when it burns for the first time
Gatta, Alessandro. "Diagrammes d'influence : Méthodologie et logiciel pour la résolution de graphes de décision." Paris 6, 1992. http://www.theses.fr/1992PA066720.
Full textLoynes, Basile de. "Graphes & marches aléatoires." Rennes 1, 2012. https://ecm.univ-rennes1.fr/nuxeo/site/esupversions/2c2ff4a7-cb0d-4f16-bdaa-3e8ec028fa8d.
Full textL'étude des marches aléatoires fait apparaître des connexions entre leurs propriétés algébriques, géométriques ou encore combinatoires et leurs propriétés stochastiques. Si les marches aléatoires sur les groupes - ou sur des espaces homogènes - fournissent beaucoup d'exemples, il serait appréciable d'obtenir de tels résultats de rigidité sur des structures algébriques plus faibles telles celles de semi-groupoide ou de groupoide. Dans cette thèse il est considéré un exemple de semi-groupoide et un exemple de groupoide, tous les deux sont définis a partir de sous-graphes contraints du graphe de Cayley d'un groupe - le premier graphe est dirige alors que le second ne l'est pas. Pour ce premier exemple, on précise un résultat de Campanino et Petritis (ils ont montre que la marche aléatoire simple était transiente pour cet exemple de graphe dirigé) en déterminant la frontière de Martin associée à cette marche et établissant sa trivialité Dans le second exemple apparaissant dans ce manuscrit, on considère des pavages quasi-périodiques de l'espace euclidien obtenus à l'aide de la méthode de coupe et projection. Nous considérons la marche aléatoire simple le long des arêtes des polytopes constituant le pavage, et nous répondons a la question du type de celle-ci, c'est-à-dire nous déterminons si elle est récurrente ou transiente. Nous montrons ce résultat en établissant des inégalités isopérimétriques Cette stratégie permet d'obtenir des estimées de la vitesse de décroissance du noyau de la chaleur, ce que n'aurait pas permis l'utilisation d'un critère de type Nash-Williams
Mercier, Lucas. "Grands graphes et grands arbres aléatoires : analyse du comportement asymptotique." Electronic Thesis or Diss., Université de Lorraine, 2016. http://www.theses.fr/2016LORR0028.
Full textThis thesis is dedicated to the study of the asymptotic behavior of some large random graphs and trees. First is studied a random graph model introduced by Bo Söderberg in 2002. One chapter of this manuscript is devoted to the study of the asymptotic behavior of the size of the connected components near the critical window, linking it to the lengths of excursion of a Brownian motion with parabolic drift. The next chapter talks about a random graph process suggested by Itai Benjamini, defined as follows: edges are independently added at a fixe rate. Whenever a vertex reaches degree k, all adjacent edges are removed. This process is non-increasing, preventing the use of some commonly used methods. By using local limits, in the spirit of the PWIT, we were able to prove the presence (resp. absence) of a giant component at some stages of the process when k>=5 (resp. k<=3). In the case k=4, these results allows to link the presence (resp. absence) of a giant component to the supercriticality (resp. criticality or subcriticality) of an associated branching process. In the last chapter, the height of random Lyndon tree is studied, and is proven to be approximately c ln n, in which c=5.092... the solution of an optimization problem. To obtain this result, we couple the Lyndon tree with a Yule tree, then studied with the help of branching walks and large deviations
Foulger, Iain. "Quantum walks and quantum search on graphene lattices." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/27717/.
Full textIriarte, Giraldo Benjamin. "Combinatorics of acyclic orientations of graphs : algebra, geometry and probability." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99325.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 96-99).
This thesis studies aspects of the set of acyclic orientations of a simple undirected graph. Acyclic orientations of a graph may be readily obtained from bijective labellings of its vertex-set with a totally ordered set, and they can be regarded as partially ordered sets. We will study this connection between acyclic orientations of a graph and the theory of linear extensions or topological sortings of a poset, from both the points of view of poset theory and enumerative combinatorics, and of the geometry of hyperplane arrangements and zonotopes. What can be said about the distribution of acyclic orientations obtained from a uniformly random selection of bijective labelling? What orientations are thence more probable? What can be said about the case of random graphs? These questions will begin to be answered during the first part of the thesis. Other types of labellings of the vertex-set, e.g. proper colorings, may be used to obtain acyclic orientations of a graph, as well. Motivated by our first results on bijective labellings, in the second part of the thesis, we will use eigenvectors of the Laplacian matrix of a graph, in particular, those corresponding to the largest eigenvalue, to label its vertex-set and to induce partial orientations of its edge-set. What information about the graph can be gathered from these partial orientations? Lastly, in the third part of the thesis, we will delve further into the structure of acyclic orientations of a graph by enhancing our understanding of the duality between the graphical zonotope and the graphical arrangement with the lens of Alexander duality. This will take us to non-crossing trees, which arguably vastly subsume the combinatorics of this geometric and algebraic duality. We will then combine all of these tools to obtain probabilistic results about the number of acyclic orientations of a random graph, and about the uniformly random choice of an acyclic orientation of a graph, among others.
by Benjamin Iriarte Giraldo.
Ph. D.
El, Hibaoui Abdelaaziz. "Analyse de quelques algorithmes probabilistes à délais aléatoires." Bordeaux 1, 2006. http://www.theses.fr/2006BOR13323.
Full textBertacchi, D., and Andreas Cap@esi ac at. "Random Walks on Diestel--Leader Graphs." ESI preprints, 2001. ftp://ftp.esi.ac.at/pub/Preprints/esi1004.ps.
Full textNyberg, Brodda Carl-Fredrik. "Deterministic and Random Pebbling of Graphs." Thesis, Uppsala universitet, Analys och sannolikhetsteori, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-325833.
Full textWilliams, Trevor K. "Combinatorial Games on Graphs." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/6502.
Full textPineau, Edouard. "Contributions to representation learning of multivariate time series and graphs." Electronic Thesis or Diss., Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAT037.
Full textMachine learning (ML) algorithms are designed to learn models that have the ability to take decisions or make predictions from data, in a large panel of tasks. In general, the learned models are statistical approximations of the true/optimal unknown decision models. The efficiency of a learning algorithm depends on an equilibrium between model richness, complexity of the data distribution and complexity of the task to solve from data. Nevertheless, for computational convenience, the statistical decision models often adopt simplifying assumptions about the data (e.g. linear separability, independence of the observed variables, etc.). However, when data distribution is complex (e.g. high-dimensional with nonlinear interactions between observed variables), the simplifying assumptions can be counterproductive. In this situation, a solution is to feed the model with an alternative representation of the data. The objective of data representation is to separate the relevant information with respect to the task to solve from the noise, in particular if the relevant information is hidden (latent), in order to help the statistical model. Until recently and the rise of modern ML, many standard representations consisted in an expert-based handcrafted preprocessing of data. Recently, a branch of ML called deep learning (DL) completely shifted the paradigm. DL uses neural networks (NNs), a family of powerful parametric functions, as learning data representation pipelines. These recent advances outperformed most of the handcrafted data in many domains.In this thesis, we are interested in learning representations of multivariate time series (MTS) and graphs. MTS and graphs are particular objects that do not directly match standard requirements of ML algorithms. They can have variable size and non-trivial alignment, such that comparing two MTS or two graphs with standard metrics is generally not relevant. Hence, particular representations are required for their analysis using ML approaches. The contributions of this thesis consist of practical and theoretical results presenting new MTS and graphs representation learning frameworks.Two MTS representation learning frameworks are dedicated to the ageing detection of mechanical systems. First, we propose a model-based MTS representation learning framework called Sequence-to-graph (Seq2Graph). Seq2Graph assumes that the data we observe has been generated by a model whose graphical representation is a causality graph. It then represents, using an appropriate neural network, the sample on this graph. From this representation, when it is appropriate, we can find interesting information about the state of the studied mechanical system. Second, we propose a generic trend detection method called Contrastive Trend Estimation (CTE). CTE learns to classify pairs of samples with respect to the monotony of the trend between them. We show that using this method, under few assumptions, we identify the true state underlying the studied mechanical system, up-to monotone scalar transform.Two graph representation learning frameworks are dedicated to the classification of graphs. First, we propose to see graphs as sequences of nodes and create a framework based on recurrent neural networks to represent and classify them. Second, we analyze a simple baseline feature for graph classification: the Laplacian spectrum. We show that this feature matches minimal requirements to classify graphs when all the meaningful information is contained in the structure of the graphs
Lehéricy, Thomas. "Cycles séparants, isopérimétrie et modifications de distances dans les grandes cartes planaires aléatoires." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS476/document.
Full textPlanar maps are planar graphs drawn on the sphere and seen up to deformation. Many properties of maps are conjectured to be universal, in the sense that they do not depend on the details of the model.We begin by establishing an isoperimetric inequality in the infinite quadrangulation of the plane. We also confirm a conjecture by Krikun concerning the length of the shortest cycles separating the ball of radius $r$ from infinity. We then consider the effect of modifications of distances on the large-scale geometry of uniform quadrangulations, extending the universality class of the Brownian map. We also show that the Tutte bijection, between quadrangulations and planar maps, is asymptotically an isometry. Finally, we establish an upper bound on the mixing time of the random walk in random maps
Bellalouna, Monia. "Problèmes d'optimisation combinatoires probabilistes." Phd thesis, Ecole Nationale des Ponts et Chaussées, 1993. http://pastel.archives-ouvertes.fr/pastel-00568759.
Full textDe, Loynes Basile. "Graphes et marches al��atoires." Phd thesis, Universit�� Rennes 1, 2012. http://tel.archives-ouvertes.fr/tel-00726504.
Full textWeld, Christopher. "Computational Graphics and Statistical Analysis: Mixed Type Random Variables, Confidence Regions, and Golden Quantile Rank Sets." W&M ScholarWorks, 2019. https://scholarworks.wm.edu/etd/1563898977.
Full textLindström, Alfred Minh. "Cutting and Destroying Graphs using k-cuts." Thesis, Uppsala universitet, Analys och sannolikhetsteori, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-395663.
Full textRoques, Olivier. "Tirages économes de structures combinatoires." Bordeaux 1, 2001. http://www.theses.fr/2001BOR12402.
Full textMosbah, Mohamed. "Constructions d'algorithmes pour les graphes structurés par des méthodes algébriques et logiques." Bordeaux 1, 1992. http://www.theses.fr/1992BOR10511.
Full textBaki, Bassam. "Planification et ordonnancement probabilistes sous contraintes temporelles." Phd thesis, Université de Caen, 2006. http://tel.archives-ouvertes.fr/tel-00127880.
Full textLes tâches et les contraintes sont représentées à l'aide d'un graphe ET/OU et les durées des tâches sont pondérées par des probabilités d'exécution. Celles-ci expriment une incertitude sur la connaissance exacte des durées d'exécution des tâches qui ne seront réellement connues que lors de l'exécution effective. Ainsi, une tâche s'exécute durant l'une de ses durées d'exécution possibles avec la probabilité associée à celle-ci. Étant donné ce graphe, notre objectif est de déterminer un plan de tâches qui satisfait toutes les contraintes et qui répond aux critères de choix exigés par l'utilisateur en terme de temps, de coût et de probabilité. L'application de ce plan doit garantir le monde de façon que le but soit atteint tout en satisfaisant les contraintes du domaine.
Nous avons appliqué notre méthode de planification à un cas pratique relativement complexe qui concerne la planification d'un ensemble d'agents travaillant ensemble dans un lieu afin d'atteindre un but donné tout en respectant les délais et les contraintes du domaine (temps, coût, probabilité, disponibilité, spécialité,...).
Bosi, Gianluca <1991>. "Simple random walks on some partially directed planar graphs." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amsdottorato.unibo.it/8914/1/bosi_gianluca_tesi.pdf.
Full textPirot, Francois. "Coloration de graphes épars." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0153.
Full textThis thesis focuses on generalisations of the colouring problem in various classes of sparse graphs.Triangle-free graphs of maximum degree d are known to have independence ratio at least (1-o(1))ln d/d by a result of Shearer [She83], and chromatic number at most O(d/ln d) by a result of Johansson [Joh96], as d grows to infinity. This was recently improved by Molloy, who showed that the chromatic number of triangle-free graphs of maximum degree d is at most (1+o(1))d/ln d as d grows to infinity.While Molloy's result is expressed with a global parameter, the maximum degree of the graph, we first show that it is possible to extend it to local colourings. Those are list colourings where the size of the list associated to a given vertex depends only on the degree of that vertex. With a different method relying on the properties of the hard-core distribution on the independent sets of a graph, we obtain a similar result for local fractional colourings, with weaker assumptions. We also provide an analogous result concerning local fractional colourings of graphs where each vertex is contained in a bounded number of triangles, and a sharp bound for the occupancy fraction — the average size of an independent set — of those graphs. In another direction, we also consider graphs of girth 7, and prove related results which improve on the previously known bounds when the maximum degree does not exceed 10^7. Finally, for d-regular graphs with d in the set {3,4,5}, of girth g varying between 6 and 12, we provide new lower bounds on the independence ratio.The second chapter is dedicated to distance colourings of graphs, a generalisation of strong edge-colourings. Extending the theme of the first chapter, we investigate minimal sparsity conditions in order to obtain Johansson-like results for distance colourings. While Johansson's result follows from the exclusion of triangles — or actually of cycles of any fixed length — we show that excluding cycles of length 2k, provided that k>t, has a similar effect for the distance-t chromatic number and the distance-(t+1) chromatic index. When t is odd, the same holds for the distance-t chromatic number by excluding cycles of fixed odd length at least 3t. We investigate the asymptotic sharpness of our results with constructions of combinatorial, algebraic, and probabilistic natures.In the third chapter, we are interested in the bipartite induced density of triangle-free graphs, a parameter which conceptually lies between the independence ratio and the fractional chromatic number. Motivated by a conjecture of Esperet, Kang, and Thomassé [EKT19], which states that the bipartite induced density of a triangle-free graph of average degree d should be at least of the order of ln d, we prove that the conjecture holds for when d is large enough in terms of the number of vertices n, namely d is at least of the order of (n ln n)^(1/2). Our result is shown to be sharp up to term of the order of ln n, with a construction relying on the triangle-free process. Our work on the bipartite induced density raises an interesting related problem, which aims at determining the maximum possible fractional chromatic number of sparse graph where the only known parameter is the number of vertices. We prove non trivial upper bounds for triangle-free graphs, and graphs where each vertex belongs to a bounded number of triangles.All the content of this thesis is a collection of specialisations of the off-diagonal Ramsey theory. To this date, the best-known bounds on the off-diagonal Ramsey number R(3,t) come from the aforementioned result of Shearer for the upper-bound, and a recent analysis of the triangle-free process [BoKe13+,FGM13+] for the lower bound, giving(1-o(1)) t²/(4 ln t) < R(3,t) < (1+o(1)) t²/ln t. (1)Many of our results are best possible barring an improvement of (1), which would be a breakthrough in off-diagonal Ramsey theory
Male, Camille. "Forte et fausse libertés asymptotiques de grandes matrices aléatoires." Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2011. http://tel.archives-ouvertes.fr/tel-00673551.
Full textDe, Loynes Basile. "Graphes et marches aléatoires." Phd thesis, Université Rennes 1, 2012. http://tel.archives-ouvertes.fr/tel-00726483.
Full textJin, Xiong. "Construction et analyse multifractale de fonctions aléatoires et de leurs graphes." Phd thesis, Université Paris Sud - Paris XI, 2010. http://tel.archives-ouvertes.fr/tel-00841501.
Full textWang, Xiaomin. "Décider du type de distribution de degré d'un graphe (réseau) à partir des mesures traceroute-like." Paris 6, 2011. http://www.theses.fr/2011PA066608.
Full textRousselle, Arnaud. "Marches au hasard sur des graphes géométriques aléatoires engendrés par des processus ponctuels." Rouen, 2014. http://www.theses.fr/2014ROUES038.
Full textRandom walks on random graphs embedded in Rd appear naturally in problems arising from statistical mechanics such that the description of flows, molecules or heat diffusions in random and irregular environments. The general idea is to extend known results for random walks on Zd or on random perturbations of the grid to results for random walks on graphs generated by point processes in Rd. In this thesis, we consider nearest neighbor random walks on graphs depending on the geometry of a random infinite locally finite set of points. More precisely, given a realisation of a simple stationary point process in Rd, a connected infinite and locally finite graph G is constructed. This graph is then possibly equipped with a conductance function C, that is a positive function defined on its edge set. Examples of graphs studied in this manuscript are the Delaunay triangulation, the Gabriel graph, the creek-crossing graphs and the skeleton of the Voronoi tiling generated by the point process. We study properties of the simple random walk or of a random walk associated with the conductance C on such graphs. The main results concern the characterisation of the recurrence or transience of the random walks and the description of their diffusive scaling limits. Under suitable assumptions on the underlying point process and the conductance function, we show that the random walks on the Delaunay triangulation, the Gabriel graph and the skeleton of the Voronoi tiling generated by almost every realisation of the point process are recurrent if d = 2 and transient if d ≥ 3. We state an annealed invariance principle for simple random walks starting from the origin on the Delaunay triangulation, the Gabriel graph and the creek-crossing graphs generated by Palm measures of suitable point processes. Finally, we show a quenched invariance principle for simple random walks on random Delaunay triangulations. This thesis uses tools from both stochastic geometry (point processes, Palm measures, random graphs. . . ) and the theory of random walks (links with electrical networks theory, the environment seen from the particle,. . . )
Gillet, Florent. "Etude d'algorithmes stochastiques et arbres." Nancy 1, 2003. http://www.theses.fr/2003NAN10191.
Full textThis thesis deals with the probabilistic analysis of some problems comming from computer science and combinatoric. In a first part, we study the effects of errors of comparison when we sort an input list with the sorting algorithm Quicksort. When a comparison can err with probability p, we show that the number of inversions in the output list of Quicksort has the order of magnitude n2p. In the second part, we prove the convergence of a process known as watermelon to a process defined by stochastic differential equations. We also give some properties of this limit process: the law of his norm, some moments, a link with the eigen values of random matrices,. . . The last part deals with the study of the asymptotic behaviour of the local laws of simple trees. We show that the law of simple trees with n vertices converges to a probablity measure we describe
Bailey, Sean. "To Dot Product Graphs and Beyond." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/5029.
Full textMcKinnon, Melissa Taylor. "Probability and Statistics for Third through Fifth Grade Classrooms." Digital Commons @ East Tennessee State University, 2007. https://dc.etsu.edu/etd/2118.
Full textPirot, Francois. "Coloration de graphes épars." Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0153/document.
Full textThis thesis focuses on generalisations of the colouring problem in various classes of sparse graphs.Triangle-free graphs of maximum degree d are known to have independence ratio at least (1-o(1))ln d/d by a result of Shearer [She83], and chromatic number at most O(d/ln d) by a result of Johansson [Joh96], as d grows to infinity. This was recently improved by Molloy, who showed that the chromatic number of triangle-free graphs of maximum degree d is at most (1+o(1))d/ln d as d grows to infinity.While Molloy's result is expressed with a global parameter, the maximum degree of the graph, we first show that it is possible to extend it to local colourings. Those are list colourings where the size of the list associated to a given vertex depends only on the degree of that vertex. With a different method relying on the properties of the hard-core distribution on the independent sets of a graph, we obtain a similar result for local fractional colourings, with weaker assumptions. We also provide an analogous result concerning local fractional colourings of graphs where each vertex is contained in a bounded number of triangles, and a sharp bound for the occupancy fraction — the average size of an independent set — of those graphs. In another direction, we also consider graphs of girth 7, and prove related results which improve on the previously known bounds when the maximum degree does not exceed 10^7. Finally, for d-regular graphs with d in the set {3,4,5}, of girth g varying between 6 and 12, we provide new lower bounds on the independence ratio.The second chapter is dedicated to distance colourings of graphs, a generalisation of strong edge-colourings. Extending the theme of the first chapter, we investigate minimal sparsity conditions in order to obtain Johansson-like results for distance colourings. While Johansson's result follows from the exclusion of triangles — or actually of cycles of any fixed length — we show that excluding cycles of length 2k, provided that k>t, has a similar effect for the distance-t chromatic number and the distance-(t+1) chromatic index. When t is odd, the same holds for the distance-t chromatic number by excluding cycles of fixed odd length at least 3t. We investigate the asymptotic sharpness of our results with constructions of combinatorial, algebraic, and probabilistic natures.In the third chapter, we are interested in the bipartite induced density of triangle-free graphs, a parameter which conceptually lies between the independence ratio and the fractional chromatic number. Motivated by a conjecture of Esperet, Kang, and Thomassé [EKT19], which states that the bipartite induced density of a triangle-free graph of average degree d should be at least of the order of ln d, we prove that the conjecture holds for when d is large enough in terms of the number of vertices n, namely d is at least of the order of (n ln n)^(1/2). Our result is shown to be sharp up to term of the order of ln n, with a construction relying on the triangle-free process. Our work on the bipartite induced density raises an interesting related problem, which aims at determining the maximum possible fractional chromatic number of sparse graph where the only known parameter is the number of vertices. We prove non trivial upper bounds for triangle-free graphs, and graphs where each vertex belongs to a bounded number of triangles.All the content of this thesis is a collection of specialisations of the off-diagonal Ramsey theory. To this date, the best-known bounds on the off-diagonal Ramsey number R(3,t) come from the aforementioned result of Shearer for the upper-bound, and a recent analysis of the triangle-free process [BoKe13+,FGM13+] for the lower bound, giving(1-o(1)) t²/(4 ln t) < R(3,t) < (1+o(1)) t²/ln t. (1)Many of our results are best possible barring an improvement of (1), which would be a breakthrough in off-diagonal Ramsey theory
Phadnis, Miti. "Statistical Analysis of Linear Analog Circuits Using Gaussian Message Passing in Factor Graphs." DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/504.
Full textAhlquist, Blair 1979. "Probability on graphs: A comparison of sampling via random walks and a result for the reconstruction problem." Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/11144.
Full textWe compare the relaxation times of two random walks - the simple random walk and the metropolis walk - on an arbitrary finite multigraph G. We apply this result to the random graph with n vertices, where each edge is included with probability p = [Special characters omitted.] where λ > 1 is a constant and also to the Newman-Watts small world model. We give a bound for the reconstruction problem for general trees and general 2 × 2 matrices in terms of the branching number of the tree and some function of the matrix. Specifically, if the transition probabilities between the two states in the state space are a and b , we show that we do not have reconstruction if Br( T ) [straight theta] < 1, where [Special characters omitted.] and Br( T ) is the branching number of the tree in question. This bound agrees with a result obtained by Martin for regular trees and is obtained by more elementary methods. We prove an inequality closely related to this problem.
Committee in charge: David Levin, Chairperson, Mathematics; Christopher Sinclair, Member, Mathematics; Marcin Bownik, Member, Mathematics; Hao Wang, Member, Mathematics; Van Kolpin, Outside Member, Economics
Sahnoun, Réda. "Composition asymptotique de processus d'urne de Pólya et applications à l'algorithmique." Versailles-St Quentin en Yvelines, 2010. http://www.theses.fr/2010VERS0051.
Full textPolya processes are discrete-time random walks in R^d, natural generalizations of Pólya-Eggenberger urns. In this latter model, a urn may contain balls of different colors and a matrix (deterministic) with integer coefficients describes the rules for replacement after each draw. Many situations from the computer sciences (tree structures) or theoretical physics (percolation fragmentation) are modeled by these objects. The asymptotic behavior of these processes reveals a new family of probability laws, some of them are determined by their moments, while for the other, the exponential generating function of moments diverges. This attests to the richness of this model, however, the cases reviewed permit to identify the complex combinatorics of the general case
Rombach, Michaela Puck. "Colouring, centrality and core-periphery structure in graphs." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:7326ecc6-a447-474f-a03b-6ec244831ad4.
Full textAverous, Jean, and Michel Meste. "Famille de boules centrales d'une probabilité sur un espace de Banach. Application aux ordres et mesures de dissymétrie et de kurtosis." Toulouse 3, 1992. http://www.theses.fr/1992TOU30017.
Full textRangel, Walteros Pedro Andres. "A non-asymptotic study of low-rank estimation of smooth kernels on graphs." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52988.
Full textFavier, Aurélie. "Décompositions fonctionnelles et structurelles dans les modèles graphiques probabilistes appliquées à la reconstruction d'haplotypes." Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1527/.
Full textThis thesis is based on two topics : the decomposition in graphical models which are, among others, Bayesian networks and cost function networks (WCSP) and the haplotype reconstruction in pedigrees. We apply techniques of WCSP to treat Bayesian network. We exploit stuctural and fonctional properties, in an exact and approached methods. Particulary, we define a decomposition of function which produces functions with a smaller variable number. An application example in optimization is the haplotype reconstruction. It is essential for a best prediction of seriousness of disease or to understand particular physical characters. Haplotype reconstruction is represented with a Bayesian network. The functionnal decomposition allows to reduce this Bayesian network in an optimization problem WCSP (Max-2SAT)
Zappella, G. "LEARNING ON GRAPHS: ALGORITHMS FOR CLASSIFICATION AND SEQUENTIAL DECISIONS." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/234167.
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