English

Growth and decay of H\"older moduli

Classical Analysis and ODEs 2023-07-20 v1

Abstract

If f:RdCf:{\bf R}^d\to{\bf C} is bounded and ff's H\"older α\alpha-modulus of continuity grows no faster than (1+x)M(1+\vert x\vert)^M (M0M\geq0) then, for every ϵ>0\epsilon>0, there is a β>0\beta>0 such that ff's H\"older β\beta-modulus grows no faster than (1+x)ϵ(1+\vert x\vert)^{\epsilon}. We use this easy fact to show that, if f\vert f\vert decays as fast as (1+x)R(1+\vert x\vert)^{-R} (for R>0R>0) and ff's α\alpha-H\"older modulus grows no faster than (1+x)M(1+\vert x\vert)^M, then, for every 0R<R0\leq R'< R, there is a β>0\beta>0 such that ff's β\beta-H\"older modulus decays as fast as (1+x)R(1+\vert x\vert)^{-R'}. We apply this to strengthen a result of Coifman and Meyer on almost-orthogonality of vaguelet families and to derive other useful facts about vaguelets and vaguelet-like functions.

Keywords

Cite

@article{arxiv.2307.09525,
  title  = {Growth and decay of H\"older moduli},
  author = {James Michael Wilson},
  journal= {arXiv preprint arXiv:2307.09525},
  year   = {2023}
}