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On vector functions of bounded convexity

Libor Veselý, Luděk Zajíček (2008)

Mathematica Bohemica

Let X be a normed linear space. We investigate properties of vector functions F : [ a , b ] X of bounded convexity. In particular, we prove that such functions coincide with the delta-convex mappings admitting a Lipschitz control function, and that convexity K a b F is equal to the variation of F + ' on [ a , b ) . As an application, we give a simple alternative proof of an unpublished result of the first author, containing an estimate of convexity of a composed mapping.

Opérateurs dissipatifs et semi-groupes dans les espaces de fonctions continues

Jean-Pierre Roth (1976)

Annales de l'institut Fourier

Soit X un espace localement compact. Tout opérateur dissipatif de domaine dense dans C 0 ( ( X ) est limite d’opérateurs dissipatifs bornés. Ce résultat permet, dans le cas où X est un espace homogène, de démontrer que tout opérateur dissipatif, de domaine dense et invariant sur C 0 ( X ) se prolonge en le générateur infinitésimal d’un semi-groupe à contraction invariant sur C 0 ( X ) .À tout opérateur A vérifiant le principe du maximum positif sur C 0 ( X , R ) et de domaine assez riche, on associe un opérateur bilinéaire B , appelé...

Porous medium equation and fast diffusion equation as gradient systems

Samuel Littig, Jürgen Voigt (2015)

Czechoslovak Mathematical Journal

We show that the Porous Medium Equation and the Fast Diffusion Equation, u ˙ - Δ u m = f , with m ( 0 , ) , can be modeled as a gradient system in the Hilbert space H - 1 ( Ω ) , and we obtain existence and uniqueness of solutions in this framework. We deal with bounded and certain unbounded open sets Ω n and do not require any boundary regularity. Moreover, the approach is used to discuss the asymptotic behaviour and order preservation of solutions.

Practical Ulam-Hyers-Rassias stability for nonlinear equations

Jin Rong Wang, Michal Fečkan (2017)

Mathematica Bohemica

In this paper, we offer a new stability concept, practical Ulam-Hyers-Rassias stability, for nonlinear equations in Banach spaces, which consists in a restriction of Ulam-Hyers-Rassias stability to bounded subsets. We derive some interesting sufficient conditions on practical Ulam-Hyers-Rassias stability from a nonlinear functional analysis point of view. Our method is based on solving nonlinear equations via homotopy method together with Bihari inequality result. Then we consider nonlinear equations...

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