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Artículo
The fixed point property and unbounded sets in CAT(0) spaces
(Elsevier, 2013-12-15)
In this work we study the fixed point property for nonexpansive self-mappings defined on convex and closed subsets of a CAT(0) space. We will show that a positive answer to this problem is very much linked with the Euclidean ...
Artículo
Hardy-Littlewood inequalities for norms of positive operators on sequence spaces
(Elsevier, 2013-01-01)
We consider estimates of Hardy and Littlewood for norms of operators on sequence spaces, and we apply a factorization result of Maurey to obtain improved estimates and simplified proofs for the special case of a positive operator.
Artículo
Function algebras with a strongly precompact unit ball
(Elsevier, 2013-10-01)
Let µ be a finite positive Borel measure with compact support K ⊆ C, and regard L∞(µ) as an algebra of multiplication operators on the Hilbert space L2(µ). Then consider the subalgebra A(K) of all continuous functions on ...
Artículo
Density of the set of renormings in c0 without asymptotically isometric copies of c0 and failing to have the fixed point property
(Casa Cărţii de Ştiinţă Cluj-Napoca, 2013)
It is proved that the family of all equivalent norms in c0 without asymptotically isometric copies of c0 and failing to have the fixed point property is dense in the set of all renormings of c0.
Artículo
Exponential decay estimates for singular integral operators
(Springer, 2013-12)
The following subexponential estimate for commutators is proved |{x ∈ Q : |[b, T]f(x)| > tM2 f(x)}| ≤ c e− √ α tkbkBMO |Q|, t > 0. where c and α are absolute constants, T is a Calder´on–Zygmund operator, M is the Hardy ...
Artículo
A dynamical characterization of sub-Arakelian subsets
(Elsevier, 2013-09-15)
We are going to characterize those sets which can be covered by an Arakelian set in terms of dynamical properties of entire functions via similarities. Moreover, if we consider the set of universal entire functions via ...