Jorge Antezana

Oblique projections and frames

We characterize those frames on a Hilbert space H which can be represented as the image of an orthonormal basis by an oblique projection defined on an extension K of H. We show that all frames with infinite excess and frame bounds 1 < A < B are of this type. This gives a generalization of a result of Han and Larson which only holds for normalized tight frames.

Nullspaces and frames

In this paper we give new characterizations of Riesz and conditional Riesz frames in terms of the properties of the nullspace of their synthesis operators. On the other hand, we also study the oblique dual frames whose coefficients in the reconstruction formula minimize different weighted norms.

Lorentz-Shimogaki and Boyd theorems for weighted Lorentz spaces

Fil: Agora, Elona. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Saavedra 15. Instituto Argentino de Matematica; Argentina. Universidad de Barcelona; Espana