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Artículo
On regularization in superreflexive Banach spaces by infimal convolution formulas
(Polish Academy of Sciences, Institute of Mathematics, 1998)
We present here a new method for approximating functions defined on superreflexive Banach spaces by differentiable functions with α-H¨older derivatives (for some 0 < α ≤ 1). The smooth approximation is given by means of ...
Artículo
Asymptotics of Keiper-Li coefficients
(Adam Mickiewicz University, Faculty of Mathematics and Computer Science, 2011)
We show that the Riemann Hypothesis is equivalent to the assertion (ym)∈ℓ2 where ymym is defined by λm=1/2(logm+γ−log(2π)−1)+ym, and mλm represents the numbers in Xian-Jin Li's criterion. This confirms and further sharpens ...
Artículo
A continuation method for weakly Kannan maps
(SpringerOpen, 2010)
The first continuation method for contractive maps in the setting of a metric space was given by Granas. Later, Frigon extended Granas theorem to the class of weakly contractive maps, and recently Agarwal and O’Regan have ...
Artículo
A continuation method for weakly contractive mappings under the interior condition
(Hindawi, 2009)
Recently, Frigon proved that, for weakly contractive maps, the property of having a fixed point is invariant by a certain class of homotopies, obtaining as a consequence a Leray-Schauder alternative for this class of maps ...
Artículo
Weak type estimates for singular integrals related to a dual problem of Muckenhoupt-Wheeden
(Springer, 2009-06)
A well known open problem of Muckenhoupt-Wheeden says that any Calderón-Zygmund singular integral operator T is of weak type (1, 1) with respect to a couple of weights (w, Mw). In this paper we consider a somewhat “dual” ...
Artículo
A new characterization of the Muckenhoupt Ap weights through an extension of the Lorentz-Shimogaki theorem
(Indiana University, 2007)
Given any quasi-Banach function space X over Rn it is defined an index αX that coincides with the upper Boyd index αX when the space X is rearrangement-invariant. This new index is defined by means of the local maximal ...
Artículo
New maximal functions and multiple weights for the multilinear Calderón-Zygmund theory
(Elsevier, 2009-03-01)
A multi(sub)linear maximal operator that acts on the product of m Lebesgue spaces and is smaller that the m-fold product of the Hardy-Littlewood maximal function is studied. The operator is used to obtain a precise control ...
Artículo
A1 bounds for Calderón-Zygmund operators related to a problem of Muckenhoupt and Wheeden
(International Press, 2009)
We obtain an Lp(w) bound for Calderón-Zygmund operators T when w ∈ A1. This bound is sharp both with respect to ∥w∥A1 and with respect to p. As a result, we get a new L1,∞(w) estimate for T related to a problem of Muckenhoupt ...
Artículo
Invariant means and thin sets in harmonic analysis with applications to prime numbers
(Wiley, 2009-08)
We first prove a localization principle characterising Lust-Piquard sets. We obtain that the union of two Lust-Piquard sets is a Lust-Piquard set, provided that one of these two sets is closed for the Bohr topology. We ...
Artículo
Heisenberg uniqueness pairs and the Klein-Gordon equation
(Princeton University, 2011)
A Heisenberg uniqueness pair (HUP) is a pair (Γ, Λ), where Γ is a curve in the plane and Λ is a set in the plane, with the following property: any bounded Borel measure µ in the plane supported on Γ, which is absolutely ...