<p>We show that for a large class of planar 1-dimensional random fractals <InlineEquation ID="IEq1"> <EquationSource Format="MATHML"><math> <mi>S</mi> </math></EquationSource> <EquationSource Format="TEX">$S$</EquationSource> </InlineEquation>, the Favard length <InlineEquation ID="IEq2"> <EquationSource Format="MATHML"><math> <mo>Fav</mo> <mo stretchy="false">(</mo> <mi>S</mi> <mo stretchy="false">(</mo> <mi>r</mi> <mo stretchy="false">)</mo> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$\operatorname{Fav}(S(r))$</EquationSource> </InlineEquation> of the neighborhood <InlineEquation ID="IEq3"> <EquationSource Format="MATHML"><math> <mi>S</mi> <mo stretchy="false">(</mo> <mi>r</mi> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$S(r)$</EquationSource> </InlineEquation> is comparable to <InlineEquation ID="IEq4"> <EquationSource Format="MATHML"><math> <msup> <mo>log</mo> <mrow> <mo>−</mo> <mn>1</mn> </mrow> </msup> <mo stretchy="false">(</mo> <mn>1</mn> <mo stretchy="false">/</mo> <mi>r</mi> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$\log ^{-1}(1/r)$</EquationSource> </InlineEquation>, matching a universal lower bound; up to now, this was only known in expectation for a few concrete models. In particular, we show that there exist 1-Ahlfors regular sets with the fastest possible Favard length decay. For a wide class of planar one-dimensional “grid random fractals”, including fractal percolation and its Ahlfors-regular variants, we further show that <InlineEquation ID="IEq5"> <EquationSource Format="MATHML"><math> <mo>Fav</mo> <mo stretchy="false">(</mo> <mi>S</mi> <mo stretchy="false">(</mo> <mi>r</mi> <mo stretchy="false">)</mo> <mo stretchy="false">)</mo> <mo stretchy="false">/</mo> <mo>log</mo> <mo stretchy="false">(</mo> <mn>1</mn> <mo stretchy="false">/</mo> <mi>r</mi> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$\operatorname{Fav}(S(r))/\log (1/r)$</EquationSource> </InlineEquation> converges almost surely, and we identify the limit explicitly. Furthermore, we prove that for some 1-dimensional Ahlfors-regular random fractals <InlineEquation ID="IEq6"> <EquationSource Format="MATHML"><math> <mi>S</mi> </math></EquationSource> <EquationSource Format="TEX">$S$</EquationSource> </InlineEquation>, the Favard length of <InlineEquation ID="IEq7"> <EquationSource Format="MATHML"><math> <mi>S</mi> <mo stretchy="false">(</mo> <mi>r</mi> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$S(r)$</EquationSource> </InlineEquation> decays instead like <InlineEquation ID="IEq8"> <EquationSource Format="MATHML"><math> <mo>log</mo> <mo>log</mo> <mo stretchy="false">(</mo> <mn>1</mn> <mo stretchy="false">/</mo> <mi>r</mi> <mo stretchy="false">)</mo> <mo stretchy="false">/</mo> <mo>log</mo> <mo stretchy="false">(</mo> <mn>1</mn> <mo stretchy="false">/</mo> <mi>r</mi> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$\log \log (1/r)/\log (1/r)$</EquationSource> </InlineEquation>, showing that the <InlineEquation ID="IEq9"> <EquationSource Format="MATHML"><math> <mn>1</mn> <mo stretchy="false">/</mo> <mo>log</mo> <mo stretchy="false">(</mo> <mn>1</mn> <mo stretchy="false">/</mo> <mi>r</mi> <mo stretchy="false">)</mo> </math></EquationSource> <EquationSource Format="TEX">$1/\log (1/r)$</EquationSource> </InlineEquation> decay is not universal among random fractals, as might be expected from previous results.</p>

错误:搜索内容不能为空,请输入英文关键词
错误:关键词超出字数限制,请精简
高级检索

Sharp Favard Length of Random Cantor Sets

  • Alan Chang,
  • Pablo Shmerkin,
  • Ville Suomala

摘要

We show that for a large class of planar 1-dimensional random fractals S $S$ , the Favard length Fav ( S ( r ) ) $\operatorname{Fav}(S(r))$ of the neighborhood S ( r ) $S(r)$ is comparable to log 1 ( 1 / r ) $\log ^{-1}(1/r)$ , matching a universal lower bound; up to now, this was only known in expectation for a few concrete models. In particular, we show that there exist 1-Ahlfors regular sets with the fastest possible Favard length decay. For a wide class of planar one-dimensional “grid random fractals”, including fractal percolation and its Ahlfors-regular variants, we further show that Fav ( S ( r ) ) / log ( 1 / r ) $\operatorname{Fav}(S(r))/\log (1/r)$ converges almost surely, and we identify the limit explicitly. Furthermore, we prove that for some 1-dimensional Ahlfors-regular random fractals S $S$ , the Favard length of S ( r ) $S(r)$ decays instead like log log ( 1 / r ) / log ( 1 / r ) $\log \log (1/r)/\log (1/r)$ , showing that the 1 / log ( 1 / r ) $1/\log (1/r)$ decay is not universal among random fractals, as might be expected from previous results.