Nouvelles propriétés des espaces et
Dans cet article, en utilisant les algèbres de Jordan euclidiennes, nous étudions l’espace de Hardy d’un espace symétrique de type Cayley . Nous montrons que le noyau de Cauchy-Szegö de s’exprime comme somme d’une série faisant intervenir la fonction de Harish-Chandra de l’espace symétrique riemannien , la fonction de l’espace symétrique -dual de et les fonctions sphériques de l’espace symétrique ordonné . Nous établissons, dans le cas où la dimension de l’algèbre de Jordan associée...
Two new convergences of closed linear subspaces in the real separable Hilbert space are defined. These are the uniform strong convergence and the simultaneously strong and weak convergence to a single limit. Both convergences are characterized and it is shown that they verify the three axioms of Fréchet.
The internal and boundary exact null controllability of nonlinear convective heat equations with homogeneous Dirichlet boundary conditions are studied. The methods we use combine Kakutani fixed point theorem, Carleman estimates for the backward adjoint linearized system, interpolation inequalities and some estimates in the theory of parabolic boundary value problems in Lk.
We first prove an abstract result for a class of nonlocal problems using fixed point method. We apply this result to equations revelant from plasma physic problems. These equations contain terms like monotone or relative rearrangement of functions. So, we start the approximation study by using finite element to discretize this nonstandard quantities. We end the paper by giving a numerical resolution of a model containing those terms.
We show that the numerical index of a -, -, or -sum of Banach spaces is the infimum of the numerical indices of the summands. Moreover, we prove that the spaces C(K,X) and (K any compact Hausdorff space, μ any positive measure) have the same numerical index as the Banach space X. We also observe that these spaces have the so-called Daugavet property whenever X has the Daugavet property.
We introduce new concepts of numerical range and numerical radius of one operator with respect to another one, which generalize in a natural way the known concepts of numerical range and numerical radius. We study basic properties of these new concepts and present some examples.