English

An elementary proof of an isoperimetric inequality for paths with finite $p$-variation

Classical Analysis and ODEs 2018-01-03 v1

Abstract

In this article we will prove that if the continuous closed curve γ:[0,1]R2\gamma : [0, 1] \rightarrow \mathbb{R}^2 has finite pp-variation with p<2p < 2, then (R2η(γ,(x,y))qdxdy)1/q(12)1q(ζ(2pq)1)(γp,[0,1])2q(\iint\limits_{\mathbb{R}^2}|\eta(\gamma, (x, y))|^q \,dx \,dy)^{1/q} \le (\frac{1}{2})^\frac{1}{q}(\zeta(\frac{2}{pq})-1)(||\gamma||_{p, [0, 1]})^{\frac{2}{q}} for all q[1,2p)q \in [1, \frac{2}{p}), where η(γ,(x,y))\eta(\gamma, (x, y)) is the winding number of γ\gamma at (x,y),ζ(x, y), \zeta is the Reimann zeta function, and γp,[0,1]||\gamma||_{p, [0, 1]} is the pp-variation of γ\gamma on the interval [0,1][0, 1]. Our main contribution is that we have explicitly given a bound by known constants, and we have found this by an elementary proof. We are going to be using a method introduced by L.C. Young in 1936.

Keywords

Cite

@article{arxiv.1801.00303,
  title  = {An elementary proof of an isoperimetric inequality for paths with finite $p$-variation},
  author = {George Galvin},
  journal= {arXiv preprint arXiv:1801.00303},
  year   = {2018}
}

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Due to appear in the Real Analysis Exchange