{"title":"Optimal regularity for supercritical parabolic obstacle problems","authors":"Xavier Ros-Oton, Clara Torres-Latorre","doi":"10.1002/cpa.22166","DOIUrl":null,"url":null,"abstract":"<p>We study the obstacle problem for parabolic operators of the type <math>\n <semantics>\n <mrow>\n <msub>\n <mi>∂</mi>\n <mi>t</mi>\n </msub>\n <mo>+</mo>\n <mi>L</mi>\n </mrow>\n <annotation>$\\partial _t + L$</annotation>\n </semantics></math>, where <i>L</i> is an elliptic integro-differential operator of order 2<i>s</i>, such as <math>\n <semantics>\n <msup>\n <mrow>\n <mo>(</mo>\n <mo>−</mo>\n <mi>Δ</mi>\n <mo>)</mo>\n </mrow>\n <mi>s</mi>\n </msup>\n <annotation>$(-\\Delta )^s$</annotation>\n </semantics></math>, in the supercritical regime <math>\n <semantics>\n <mrow>\n <mi>s</mi>\n <mo>∈</mo>\n <mo>(</mo>\n <mn>0</mn>\n <mo>,</mo>\n <mfrac>\n <mn>1</mn>\n <mn>2</mn>\n </mfrac>\n <mo>)</mo>\n </mrow>\n <annotation>$s \\in (0,\\frac{1}{2})$</annotation>\n </semantics></math>. The best result in this context was due to Caffarelli and Figalli, who established the <math>\n <semantics>\n <msubsup>\n <mi>C</mi>\n <mi>x</mi>\n <mrow>\n <mn>1</mn>\n <mo>,</mo>\n <mi>s</mi>\n </mrow>\n </msubsup>\n <annotation>$C^{1,s}_x$</annotation>\n </semantics></math> regularity of solutions for the case <math>\n <semantics>\n <mrow>\n <mi>L</mi>\n <mo>=</mo>\n <msup>\n <mrow>\n <mo>(</mo>\n <mo>−</mo>\n <mi>Δ</mi>\n <mo>)</mo>\n </mrow>\n <mi>s</mi>\n </msup>\n </mrow>\n <annotation>$L = (-\\Delta )^s$</annotation>\n </semantics></math>, the same regularity as in the elliptic setting.</p><p>Here we prove for the first time that solutions are actually <i>more</i> regular than in the elliptic case. More precisely, we show that they are <i>C</i><sup>1, 1</sup> in space and time, and that this is optimal. We also deduce the <math>\n <semantics>\n <msup>\n <mi>C</mi>\n <mrow>\n <mn>1</mn>\n <mo>,</mo>\n <mi>α</mi>\n </mrow>\n </msup>\n <annotation>$C^{1,\\alpha }$</annotation>\n </semantics></math> regularity of the free boundary. Moreover, at all free boundary points <math>\n <semantics>\n <mrow>\n <mo>(</mo>\n <msub>\n <mi>x</mi>\n <mn>0</mn>\n </msub>\n <mo>,</mo>\n <msub>\n <mi>t</mi>\n <mn>0</mn>\n </msub>\n <mo>)</mo>\n </mrow>\n <annotation>$(x_0,t_0)$</annotation>\n </semantics></math>, we establish the following expansion:\n\n </p>","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"77 3","pages":"1724-1765"},"PeriodicalIF":3.1000,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/cpa.22166","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Communications on Pure and Applied Mathematics","FirstCategoryId":"100","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/cpa.22166","RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
We study the obstacle problem for parabolic operators of the type , where L is an elliptic integro-differential operator of order 2s, such as , in the supercritical regime . The best result in this context was due to Caffarelli and Figalli, who established the regularity of solutions for the case , the same regularity as in the elliptic setting.
Here we prove for the first time that solutions are actually more regular than in the elliptic case. More precisely, we show that they are C1, 1 in space and time, and that this is optimal. We also deduce the regularity of the free boundary. Moreover, at all free boundary points , we establish the following expansion: