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Slowly Divergent Trajectories for Weighted Singular Vectors in R^2

Number Theory 2026-07-27 v1 Dynamical Systems

Abstract

Let w=(w1,w2)w=(w_1,w_2) satisfy w1>w2>0w_1>w_2>0 and w1+w2=1w_1+w_2=1. For every function f:[0,)(0,)f:[0,\infty)\to(0,\infty) with f(t)0f(t)\to0, we prove that the set of ww-singular vectors whose weighted shortest-vector function satisfies Wx(t)logf(t)W_x(t)\ge\log f(t) for all sufficiently large tt has Hausdorff dimension sw=2(1+w1)1s_w=2-(1+w_1)^{-1}, equal to the full Hausdorff dimension of Singw(2)\operatorname{Sing}_w(2). For every 0<ν<10<\nu<1 and μ>0\mu>0, a separate power schedule gives Hausdorff dimension sws_w for the weighted uniform approximation set with rate Q1exp(μ(logQ)ν)Q^{-1}\exp\bigl(-\mu(\log Q)^\nu\bigr), whereas the lower-envelope theorem gives the same dimension for its complement in Singw(2)\operatorname{Sing}_w(2). We give a direct proof of the lower-envelope theorem by adapting the self-affine construction of Liao--Shi--Solan--Tamam to a variable sequence of return times and using an empty-denominator-window argument to control intermediate cusp excursions without further pruning the tree.

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Cite

@article{arxiv.2607.24161,
  title  = {Slowly Divergent Trajectories for Weighted Singular Vectors in R^2},
  author = {Bohan Yang},
  journal= {arXiv preprint arXiv:2607.24161},
  year   = {2026}
}

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28 pages