Dissertations / Theses on the topic 'Régularisation en espaces de Banach'
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Lazzaretti, Marta. "Algorithmes d'optimisation dans des espaces de Banach non standard pour problèmes inverses en imagerie." Electronic Thesis or Diss., Université Côte d'Azur, 2024. http://www.theses.fr/2024COAZ4009.
This thesis focuses on the modelling, the theoretical analysis and the numerical implementation of advanced optimisation algorithms for imaging inverse problems (e.g,., image reconstruction in computed tomography, image deconvolution in microscopy imaging) in non-standard Banach spaces. It is divided into two parts: in the former, the setting of Lebesgue spaces with a variable exponent map L^{p(cdot)} is considered to improve adaptivity of the solution with respect to standard Hilbert reconstructions; in the latter a modelling in the space of Radon measures is used to avoid the biases observed in sparse regularisation methods due to discretisation.In more detail, the first part explores both smooth and non-smooth optimisation algorithms in reflexive L^{p(cdot)} spaces, which are Banach spaces endowed with the so-called Luxemburg norm. As a first result, we provide an expression of the duality maps in those spaces, which are an essential ingredient for the design of effective iterative algorithms.To overcome the non-separability of the underlying norm and the consequent heavy computation times, we then study the class of modular functionals which directly extend the (non-homogeneous) p-power of L^p-norms to the general L^{p(cdot)}. In terms of the modular functions, we formulate handy analogues of duality maps, which are amenable for both smooth and non-smooth optimisation algorithms due to their separability. We thus study modular-based gradient descent (both in deterministic and in a stochastic setting) and modular-based proximal gradient algorithms in L^{p(cdot)}, and prove their convergence in function values. The spatial flexibility of such spaces proves to be particularly advantageous in addressing sparsity, edge-preserving and heterogeneous signal/noise statistics, while remaining efficient and stable from an optimisation perspective. We numerically validate this extensively on 1D/2D exemplar inverse problems (deconvolution, mixed denoising, CT reconstruction). The second part of the thesis focuses on off-the-grid Poisson inverse problems formulated within the space of Radon measures. Our contribution consists in the modelling of a variational model which couples a Kullback-Leibler data term with the Total Variation regularisation of the desired measure (that is, a weighted sum of Diracs) together with a non-negativity constraint. A detailed study of the optimality conditions and of the corresponding dual problem is carried out and an improved version of the Sliding Franke-Wolfe algorithm is used for computing the numerical solution efficiently. To mitigate the dependence of the results on the choice of the regularisation parameter, an homotopy strategy is proposed for its automatic tuning, where, at each algorithmic iteration checks whether an informed stopping criterion defined in terms of the noise level is verified and update the regularisation parameter accordingly. Several numerical experiments are reported on both simulated 2D and real 3D fluorescence microscopy data
Plût, Jérôme. "Espaces de Banach analytiques p-adiques et espaces de Banach-Colmez." Phd thesis, Université Paris Sud - Paris XI, 2009. http://tel.archives-ouvertes.fr/tel-00448628.
Baudier, Florent. "Plongements des espaces métriques dans les espaces de Banach." Phd thesis, Université de Franche-Comté, 2009. http://tel.archives-ouvertes.fr/tel-00477415.
Chaatit, Fouad. "Sur les espaces de Banach stables." Paris 7, 1985. http://www.theses.fr/1985PA07F038.
Darapaneni, Narayana. "Proximinalité dans les espaces de Banach." Paris 6, 2005. http://www.theses.fr/2005PA066583.
Procházka, Antonín. "Analyse dans les espaces de Banach." Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13801/document.
The thesis deals with four topics in the theory of Banach spaces. The first of them is a characterization of the Radon-Nikodym property using the notion of point-slice games. The second is a computation of the w* dentability index of the spaces C(K), where K is a compact of countable height. The third is a renorming result in nonseparable spaces, producing norms which are differentiable, LUR and approximated by norms of higher smoothness. The fourth topic is a Baire cathegory approach to parametric smooth variational principles. The thesis features an introduction which surveys the background of these results
Procházka, Antonín Deville Robert Hájek Petr. "Analyse dans les espaces de Banach." S. l. : S. l. : Bordeaux 1 ; Univerzita Karlova (Prague), 2009. http://ori-oai.u-bordeaux1.fr/pdf/2009/PROCHAZKA_ANTONIN_2009.pdf.
Sersouri, Abderrazzak. "Géométrie des espaces de Banach : espaces d'opérateurs, produits tensoriels, construction de normes." Paris 6, 1986. http://www.theses.fr/1986PA066431.
LANCIEN, FLORENCE. "Geometrie des espaces de banach dans certains espaces de hardy abstraits." Paris 6, 1993. http://www.theses.fr/1993PA066141.
Borel-Mathurin, Laetitia. "Isomorphismes non linéaires entre espaces de Banach." Paris 6, 2010. http://www.theses.fr/2010PA066373.
Dutrieux, Yves. "Géométrie non linéaire des espaces de Banach." Paris 6, 2002. http://www.theses.fr/2002PA066118.
Ferenczi, Valentin. "Quelques propriétés des espaces de Banach héréditairement indécomposables." Paris 1, 1995. http://www.theses.fr/1995PA010073.
Sersousi, Abderrazzak. "Géométrie des espaces de Banach espaces d'opérateurs, produits tensoriels, construction de normes /." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37601222g.
Frontisi, Julien. "Lissité et dualité dans les espaces de Banach." Paris 6, 1996. http://www.theses.fr/1996PA066153.
Ghawadrah, Ghadeer. "Théorie descriptive des ensembles et espaces de Banach." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066078/document.
This thesis deals with the descriptive set theory and the geometry of Banach spaces.The first chapter consists of the study of the descriptive complexity of the set of Banachspaces with the Bounded Approximation Property, respectively π-property, in the set ofall closed subspaces of C(∆), where ∆ is the Cantor set. We show that these sets areBorel. In addition, we show that if α<ω_1, the set of spaces with Szlenk index at most α which have a shrinking FDD is Borel. We show in the second chapter that the numberof isomorphism classes of complemented subspaces of the reflexive Orlicz function space L^Φ [0,1] is uncountable, where L^Φ [0,1]is not isomorphic to L^2 [0,1]
Raja, Matias. "Mesurabilité de Borel et renormages dans les espaces de Banach." Bordeaux 1, 1998. http://www.theses.fr/1998BOR10557.
Qiu, Yanqi. "Propriété UMD pour les espaces de Banach et d'opérateurs." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00794951.
Abdellaoui, Taoufiq. "Distances de deux lois dans les espaces de Banach." Rouen, 1994. http://www.theses.fr/1994ROUE5003.
RAUCH, PATRICK. "Pseudocomplementation dans les espaces de banach et factorisation d'operateurs." Paris 6, 1992. http://www.theses.fr/1992PA066305.
Fernandez, Miranda Mercedes. "Éléments de géométrie dans une C* algèbre." Nice, 1990. http://www.theses.fr/1990NICE4361.
Bourass, Lamiâa. "Calcul fonctionnel harmonique dans les algèbres involutives et applications." Bordeaux 1, 1997. http://www.theses.fr/1997BOR10615.
Bossard, Benoit. "Théorie descriptive des ensembles en géométrie des espaces de Banach." Paris 6, 1994. http://www.theses.fr/1994PA066502.
Maaden, Abdelhakim. "Propriétés de la goutte et aspects géométriques des espaces de Banach." Bordeaux 1, 1994. http://www.theses.fr/1994BOR10625.
Augé, Jean-Matthieu. "Quelques problèmes de dynamique linéaire dans les espaces de Banach." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2012. http://tel.archives-ouvertes.fr/tel-00744968.
El, Berdan Kassem. "Théorèmes ergodiques à plusieurs paramètres dans les espaces de Banach." Paris 6, 1995. http://www.theses.fr/1995PA066310.
Ratsimahalo, Robert. "Etude de la projection métrique dans les espaces de Banach." Pau, 1996. http://www.theses.fr/1996PAUU3030.
BESBES, MOURAD. "Points fixes et theoremes ergodiques dans les espaces de banach." Paris 6, 1991. http://www.theses.fr/1991PA066034.
Cepedello, Boiso Manuel. "Theorie de l'approximation reguliere et geometrie des espaces de banach." Paris 6, 1998. http://www.theses.fr/1998PA066653.
Moreau, Pierre. "Notions de petitesse, géométrie des espaces de Banach et hypercyclicité." Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13803/document.
There are many notions of smallness in Analysis. We will consider three of them: Haar-negligeability, Gauss-negligeability and sigma-porosity. We will study on which conditions the positive cone of a Schauder basis is Haar-null, and its consequence on the Banach space. We will also study on which conditions the set of non-hypercyclic vectors of an hypercyclic operator is Haar-null or sigma-porous
Moreau, Pierre Esterle Jean Matheron Etienne. "Notions de petitesse, géométrie des espaces de Banach et hypercyclicité." S. l. : Bordeaux 1, 2009. http://ori-oai.u-bordeaux1.fr/pdf/2009/MOREAU_PIERRE_2009.pdf.
Khamsi, Mohamed Amine. "Etude de la propriete du point fixe dans les espaces de banach et les espaces metriques." Paris 6, 1987. http://www.theses.fr/1987PA066014.
Khamsi, Mohamed Amine. "Etude de la propriété du point fixe dans les espaces de Banach et les espaces métriques." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37606532t.
Kyrézi, Ioanna. "Entropie des enveloppes convexes et applications aux opérateurs compacts." Université de Marne-la-Vallée, 1998. http://www.theses.fr/1998MARN0028.
Ouahab, Abdelmalek. "Contribution à la théorie spectrale généralisée dans les espaces de Banach." Lille 1, 1991. http://www.theses.fr/1991LIL10173.
YAHDI, MOHAMMED. "Theorie descriptive des ensembles en geometrie des espaces de banach ; exemples." Paris 6, 1998. http://www.theses.fr/1998PA066366.
Gaspari, Thierry. "Fonctions bosses et extensions lipschitziennes optimales dans les espaces de Banach." Bordeaux 1, 2003. http://www.theses.fr/2003BOR16013.
Netillard, François. "Plongements grossièrement Lipschitz et presque Lipschitz dans les espaces de Banach." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCD020/document.
The central theme of this thesis is the study of embeddings of metric spaces into Banach spaces.The first study focuses on the coarse Lipschitz embeddings between James Spaces Jp for p≻1 and p finite. We obtain that, for p,q different, Jq does not coarse Lipschitz embed into Jp. We also obtain, in the case where q≺p, that the compression exponent of Jq in Jp is lower or equal to q/p. Another natural question is to know whether we have similar results for the dual spaces of James spaces. We obtain that, for p,q different, Jp* does not coarse Lipschitz embed into Jq*. Further to this work, we establish a more general result about the coarse Lipschitz embeddability of a Banach space which has a q-AUS norm into a Banach space which has a p-AMUC norm for p≺q. With the help of a renorming theorem, we deduce also a result about the Szlenk index. Moreover, after defining the quasi-Lipschitz embeddability, which is slightly different to the almost Lipschitz embeddability, we obtain the following result: For two Banach spaces X, if X is crudely finitely representable with constant C (where C≻1) in any subspace of Y of finite codimension, then every proper subset M of X quasi-Lipschitz embeds into Y. To conclude, we obtain the following corollary: Let X be a locally minimal Banach space, and Y be a Banach space which is crudely finitely representable in X. Then, for M a proper subspace of Y, M quasi-Lipschitz embeds into X
Rosendal, Christian. "Etude descriptive de l'isomorphisme dans la classe des espaces de Banach." Paris 6, 2003. http://www.theses.fr/2003PA066480.
Lefèvre, Pascal. "Ensembles lacunaires en analyse harmonique et géométrie des espaces de Banach." Lille 1, 1998. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1998/50376-1998-381.pdf.
Brech, Christina. "Constructions génériques des espaces d'Asplund C (K)." Paris 7, 2008. http://www.theses.fr/2008PA077047.
In this work we consider a method of generic constructions of compact scattered non-metrizable spaces developed by Baumgartner, Shelah, Rabus, Juhasz and Soukup. We introduce new techniques and obtain new applications both relevant to topology of compact spaces and the geometry of Banach spaces of continuous functions. The new techniques concern new amalgamations of conditions of forcing which add the dispersed spaces as well as the generalizations of arguments of thé above-mentioned authors from points of a compact space K to Radon measures on K. As applications we obtain two compact scattered spaces K_1 and K_2 with the properties below. K_1 is a hereditarily separable space of weight aleph_1 such that C(K_1) has property (C) of Corson and does not have property (E) of Efremov. C(K_1) is the first example of such a space consistent with the négation of the continuum hypothesis. K_2 is the first (consistent) example of a compact scattered space which is hereditarily séparable and whose height is omega_2. It follow: that its hereditary Lindelof degree is aleph_2, showing the consistency of hL(K) is not smaller or equal to the successor of hd(K) for compact spaces K. C(K_2) is the first consistent example of a Banach space of density aleph_2 without uncountable biorthogonal Systems
Boufoussi, Brahim. "Espaces de Besov : caractérisation et applications." Nancy 1, 1994. http://www.theses.fr/1994NAN10077.
Ed-Dari, Elmouloudi. "Indice numérique des espaces de Banach. Théorèmes ergodiques pondérés uniformes et forts." Artois, 2003. http://www.theses.fr/2003ARTO0407.
In the first part of this thesis, we investigate the numerical index of Banach spaces. In the case of the real sequential spaces l_p, 1
Bailleul, Maxime. "Espaces de Banach de séries de DIRICHLET et leurs opérateurs de composition." Thesis, Artois, 2014. http://www.theses.fr/2014ARTO0401/document.
In this thesis we study operators on some Banach spaces of Dirichlet series. We mainly study composition operators on two families of Bergman spaces. First we give estimates of the essential norm of composition operators on Hardy spaces of Dirichlet series with help of the Nevanlinna couting function and the Carleson's measures. Second we define and study two families of Bergman spaces of Dirichlet series : we compare these new spaces and the Hardy spaces of Dirichlet series and obtain results about boundedness and compactness of compostion operators in this framework. Finally we define and study the Hardy-Orlicz spaces of Dirichlet series
Barraa, Mohamed. "Le treillis des sous-espaces hyperinvariants d'un opérateur nilpotent sur un espace de Banach." Montpellier 2, 1987. http://www.theses.fr/1987MON20144.
Guédon, Olivier. "Sections euclidiennes des corps convexes et inégalités de concentration volumique." Université de Marne-la-Vallée, 1998. http://www.theses.fr/1998MARN0021.
Chalendar, Isabelle. "Autour du problème du sous-espace invariant et théorie des algèbres duales." Bordeaux 1, 1996. http://www.theses.fr/1996BOR10659.
Marjani, Mohammed. "Interpolation linéaire associée à un générateur de semi-groupe intégré et estimation de la fonction K." Besançon, 1990. http://www.theses.fr/1990BESA2014.
De, Rancourt Noé. "Théorie de Ramsey sans principe des tiroirs et applications à la preuve de dichotomies d'espaces de Banach." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC208/document.
In the 90's, Gowers proves a Ramsey-type theorem for block-sequences in Banach spaces, in order to show two Banach-space dichotomies. Unlike most infinite-dimensional Ramsey-type results, this theorem does not rely on a pigeonhole principle, and therefore it has to have a partially game-theoretical formulation. In a first part of this thesis, we develop an abstract formalism for Ramsey theory with and without pigeonhole principle, and we prove in it an abstract version of Gowers' theorem, from which both Mathias-Silver's theorem and Gowers' theorem can be deduced. We give both an exact version of this theorem in countable spaces, and an approximate version of it in separable metric spaces. We also prove the adversarial Ramsey principle, a result generalising both the abstract Gowers' theorem and Borel determinacy of countable games. We also study the limitations of these results and their possible generalisations under additional set-theoretical hypotheses. In a second part, we apply the latter results to the proof of two Banach-space dichotomies. These dichotomies are similar to Gowers' ones, but are Hilbert-avoiding, that is, they ensure that the subspace they give is not isomorphic to a Hilbert space. These dichotomies are a new step towards the solution of a question asked by Ferenczi and Rosendal, asking whether a separable Banach space non-isomorphic to a Hilbert space necessarily contains a large number of subspaces, up to isomorphism
El, Abdouni Bouazza. "Sur une famille de cônes tangents et de dérivées généralisées : applications à la programmation mathématique." Pau, 1990. http://www.theses.fr/1990PAUU3002.
Lancien, Gilles. "Théorie de l'indice et problèmes de renormage en géométrie des espaces de Banach." Paris 6, 1992. http://www.theses.fr/1992PA066210.