Diophantine exponents for mildly restricted approximation

Yann Bugeaud, S. Kristensen

    Publikation: Bidrag til tidsskrift/Konferencebidrag i tidsskrift /Bidrag til avisTidsskriftartikelForskningpeer review

    Abstract

    We are studying the Diophantine exponent μ n,l defined for integers 1≤l<n and a vector α∈ℝ n by letting
    $$\mu_{n,l}=\sup\{\mu\geq0: 0 < \Vert\underline{x}\cdot\alpha\Vert<H(\underline{x})^{-\mu}\ \text{for infinitely many}\ \underline{x}\in\mathcal{C}_{n,l}\cap\mathbb{Z}^n\},$$
    where $\cdot$ is the scalar product, $\|\cdot\|$ denotes the distance to the nearest integer and $\mathcal{C}_{n,l}$ is the generalised cone consisting of all vectors with the height attained among the first l coordinates. We show that the exponent takes all values in the interval [l+1,∞), with the value n attained for almost all α. We calculate the Hausdorff dimension of the set of vectors α with μ n,l (α)=μ for μ≥n. Finally, letting w n denote the exponent obtained by removing the restrictions on $\underline{x}$, we show that there are vectors α for which the gaps in the increasing sequence μ n,1(α)≤...≤μ n,n-1(α)≤w n (α) can be chosen to be arbitrary.
    OriginalsprogEngelsk
    TidsskriftArkiv foer Matematik
    Vol/bind47
    Nummer2
    Sider (fra-til)243-266
    Antal sider24
    ISSN0004-2080
    DOI
    StatusUdgivet - 2009

    Fingeraftryk

    Dyk ned i forskningsemnerne om 'Diophantine exponents for mildly restricted approximation'. Sammen danner de et unikt fingeraftryk.

    Citationsformater