Tyson型集及Borel函数的图的拟对称极小性

党云贵, 文胜友

数学学报 ›› 2020, Vol. 63 ›› Issue (6) : 621-628.

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数学学报 ›› 2020, Vol. 63 ›› Issue (6) : 621-628. DOI: 10.12386/A2020sxxb0052
论文

Tyson型集及Borel函数的图的拟对称极小性

    党云贵1,2, 文胜友1
作者信息 +

Quasisymmetric Minimality of Sets of Tyson Type and Graphs of Borel Functions

    Yun Gui DANG1,2, Sheng You WEN1
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文章历史 +

摘要

本文将欧氏空间Rd中形如[0,1]×Z的集称为Tyson型集,其中d>1,Z⊂Rd-1.已知当Z是Rd-1中的紧集时,Tyson型集是拟对称极小集.本文改进了这个结果,证明了当Z是Rd-1中的Borel集时,Tyson型集仍是拟对称极小集.作为应用,我们证明了Tyson型集三个形变版本的拟对称极小性,其中一个结果是:设Z是Rd-1中的任一Borel集,hZ→R1是Borel函数,满足dimH({h≠0}∩Z)=dimH Z,则h的图Gh)是拟对称极小集,其中h的图Gh)定义为Gh)={(z,y):zZy∈[0,hz)]}.

Abstract

In this paper, sets of the form[0,1]×Z in Rd will be called sets of Tyson type, where d > 1 and Z ⊂ Rd-1. It is known that every set E of Tyson type is quasisymmetrically minimal, provided that Z is compact in Rd-1. We prove that this result holds by only assuming that Z is Borel in Rd-1. As applications, we prove that the quasisymmetric minimality of three variants of sets of Tyson type. One of the results is that the graph G(h) of h is quasisymmetrically minimal, provided that Z is a Borel set in Rd-1 and h:Z → R1 is a Borel function satisfying the condition dimH({h ≠ 0} ∩ Z)=dimH Z, where G(h)={(z, y):zZ, y ∈[0, h(z)]}.

关键词

Tyson型集 / Hausdorff维数 / 拟对称极小集

Key words

sets of Tyson type / Hausdorff dimension / quasisymmetrically minimal sets

引用本文

导出引用
党云贵, 文胜友. Tyson型集及Borel函数的图的拟对称极小性. 数学学报, 2020, 63(6): 621-628 https://doi.org/10.12386/A2020sxxb0052
Yun Gui DANG, Sheng You WEN. Quasisymmetric Minimality of Sets of Tyson Type and Graphs of Borel Functions. Acta Mathematica Sinica, Chinese Series, 2020, 63(6): 621-628 https://doi.org/10.12386/A2020sxxb0052

参考文献

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基金

国家自然科学基金资助项目(11871200,11671189);山西省高等学校科技创新项目(2019L0963)

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