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Regular and ubiquitous systems, and ℳs∞-dense sequences
Published online by Cambridge University Press: 26 February 2010
Abstract
“Regular systems” of numbers in ℝ and “ubiquitous systems” in ℝk, k ≥ 1, have been used previously to obtain lower bounds for the Hausdorff dimension of various sets in ℝ and ℝk respectively. Both these concepts make sense for systems of numbers in ℝ, but the definitions of the two types of object are rather different. In this paper it will be shown that, after certain modifications to the definitions, the two concepts are essentially equivalent.
We also consider the concept of a ℳs∞-dense sequence in ℝk, which was introduced by Falconer to construct classes of sets having “large intersection”. We will show that ubiquitous systems can be used to construct examples of ℳs∞-dense sequences. This provides a relatively easy means of constructing ℳs∞-dense sequences; a direct construction and proof that a sequence is ℳs∞-dense is usually rather difficult.
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- Research Article
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- Copyright © University College London 1992
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