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BOUCHAIB FERRAHIÝÑÇÍí ÈæÔÚíÈ ãÑÍÈÇ WelcomeBienvenue
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PhD in Mathematical sciences
Doctorat en Sciences Mathématiques
Qualification Française N° 05226158879 (25/02/2005)
Regularity of Variational Integrals
Geometry of Banach and Integral Spaces
We study regularity (lower semicontinuity, inf-compactness,...) of integrals (called also variational functionals or integral functionals) of the form $I_f(u,v)=\int\limits_\Omega f(\omega,u(\omega),v(\omega))d\mu$. Here X and Y are Banach spaces and f is a real-valued function chosen from a class of functions called "integrands" with domain $\Omega\times X\times Y$. Such variational integrals are of considerable interest in the Calculus of Variations as well as in the field of Optimal Control. In the past, most of the work done on such integrals assumed that X and Y are finite dimensional, and the tools used often required that assumption. Our purpose is to deal with the natural situation where the Banach spaces are infinite dimensional.
The inf-compactness of these variational integrals is also studied. We say that an extended real-valued function f on a topological space E is inf-compact if for all real numbers c, the set {f<= c} is compact in E. Young functions $\psi$ and Orlicz spaces $L_\psi$ are introduced into the theory. The results are stated in terms of compactness conditions in the weak topology on Orlicz space $L_\psi$.
Papers:
2. B. Ferrahi, A. Bourass et N.Saidou, Functional Measures and Inf-compactness of Integral Functionals. In “Inequality Theory and Applications”, Nova Science Publishers, Inc., New York. Vol. 4 (à paraître).
Geometry of Banach and Integral
Spaces
We study of the geometry of Banach and Integral spaces. On one hand, We studied relations between the differentiability and some geometrical properties (e.g., extremality, dentability,...) of convex functions defined on a Banach space. On the other hand, we studied extremality and dentability in Orlicz spaces $L_\psi$.
1. B. Ferrahi, A. Bourass and N.Saidou, Extremality and differentiability of convex functions. Bulletin of Polish Academy of Sciences, Vol. 51, No1 (2003) 13 - 29.
2. B. Ferrahi,A. Bourass and N. Saidou, A New Characterization of the Radon-Nikodym Property. in "Differential Equations and Applications, Vol. 3", Nova Science Publishers, Inc., New York (2004) 53 - 56.
Abstract .pdf .ps
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3. B. Ferrahi,
Extremality and Convergence in Orlicz Spaces. in
"Fixed Point
Theory and Application”, Nova
Science Publishers, Inc., New York. Vol 5
(2003) 23 - 32.
In this topic we study multivalued linear and random multivalued linear operators. The purpose is to develop the functional analysis of multivalued linear maps and random multivalued linear maps. The classical tools of functional analysis are extended to multivalued linear mappings between general topological vector spaces. We develop also Random versions of these classical tools.