Currently displaying 1 – 16 of 16

Showing per page

Order by Relevance | Title | Year of publication

On q -strictly singular operators on variable exponent spaces

Carlos BuelgaFrancisco L. Hernandez — 2015

Commentationes Mathematicae

Strictly singular operators on variable exponent (or Nakano) function spaces L p · are characterized in terms of being q -strictly singular for the values q in the essential range R p · of the exponent function. This extends a result of L. Weiss [On perturbations of Fredholm operators in L p -spaces, Proc. Amer. Math. Soc. 67 (1977), 287-292] for L p -spaces.

Disjoint strict singularity of inclusions between rearrangement invariant spaces

It is studied when inclusions between rearrangement invariant function spaces on the interval [0,∞) are disjointly strictly singular operators. In particular suitable criteria, in terms of the fundamental function, for the inclusions L ¹ L E and E L ¹ + L to be disjointly strictly singular are shown. Applications to the classes of Lorentz and Marcinkiewicz spaces are given.

Strictly singular inclusions of rearrangement invariant spaces and Rademacher spaces

If G is the closure of L in exp L₂, it is proved that the inclusion between rearrangement invariant spaces E ⊂ F is strictly singular if and only if it is disjointly strictly singular and E ⊊ G. For any Marcinkiewicz space M(φ) ⊂ G such that M(φ) is not an interpolation space between L and G it is proved that there exists another Marcinkiewicz space M(ψ) ⊊ M(φ) with the property that the M(ψ) and M(φ) norms are equivalent on the Rademacher subspace. Applications are given and a question of Milman...

Characterization of Globally Lipschitz Nemytskiĭ Operators Between Spaces of Set-Valued Functions of Bounded φ-Variation in the Sense of Riesz

N. MerentesJ. L. Sánchez Hernández — 2004

Bulletin of the Polish Academy of Sciences. Mathematics

Let (X,∥·∥) and (Y,∥·∥) be two normed spaces and K be a convex cone in X. Let CC(Y) be the family of all non-empty convex compact subsets of Y. We consider the Nemytskiĭ operators, i.e. the composition operators defined by (Nu)(t) = H(t,u(t)), where H is a given set-valued function. It is shown that if the operator N maps the space R V φ ( [ a , b ] ; K ) into R W φ ( [ a , b ] ; C C ( Y ) ) (both are spaces of functions of bounded φ-variation in the sense of Riesz), and if it is globally Lipschitz, then it has to be of the form H(t,u(t)) = A(t)u(t)...

Page 1

Download Results (CSV)