Furstenberg sets for a fractal set of directions

In this paper we study the behavior of the size of Furstenberg sets with respect to the size of the set of directions defining it. For any pair α, β ∈ (0, 1], we will say that a set E ⊂ R2 is an Fαβ-set if there is a subset L of the unit circle of Hausdorff dimension at least β and, for each directi...

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Detalles Bibliográficos
Autores: Molter, Úrsula María, Rela, Ezequiel
Tipo de recurso: artículo
Estado:Versión aceptada para publicación
Fecha de publicación:2012
País:España
Institución:Universidad de Sevilla (US)
Repositorio:idUS. Depósito de Investigación de la Universidad de Sevilla
OAI Identifier:oai:idus.us.es:11441/47719
Acceso en línea:http://hdl.handle.net/11441/47719
https://doi.org/10.1090/S0002-9939-2011-11111-0
Access Level:acceso abierto
Palabra clave:Furstenberg sets
Hausdorff dimension
Dimension function
Kakeya sets
Descripción
Sumario:In this paper we study the behavior of the size of Furstenberg sets with respect to the size of the set of directions defining it. For any pair α, β ∈ (0, 1], we will say that a set E ⊂ R2 is an Fαβ-set if there is a subset L of the unit circle of Hausdorff dimension at least β and, for each direction e in L, there is a line segment e in the direction of e such that the Hausdorff dimension of the set E∩ e is equal to or greater than α. The problem is considered in the wider scenario of generalized Hausdorff measures, giving estimates on the appropriate dimension functions for each class of Furstenberg sets. As a corollary of our main results, we obtain that dim(E) ≥ max {α + β 2 ; 2α + β − 1} for any E ∈ Fαβ. In particular we are able to extend previously known results to the “endpoint” α = 0 case.