$C^\infty$ partial regularity of the singular set in the obstacle problem

Fuente: arXiv
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Autori principali: Franceschini, Federico, Zatoń, Wiktoria
Natura: Preprint
Pubblicazione: 2021
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author Franceschini, Federico
Zatoń, Wiktoria
author_facet Franceschini, Federico
Zatoń, Wiktoria
contents We show that the singular set $Σ$ in the classical obstacle problem can be locally covered by a $C^\infty$ hypersurface, up to an "exceptional" set $E$, which has Hausdorff dimension at most $n-2$ (countable, in the $n=2$ case). Outside this exceptional set, the solution admits a polynomial expansion of arbitrarily large order. We also prove that $Σ\setminus E$ is extremely unstable with respect to monotone perturbations of the boundary datum. We apply this result to the planar Hele-Shaw flow, showing that the free boundary can have singular points for at most countable many times.
format Preprint
id arxiv_https___arxiv_org_abs_2102_00923
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle $C^\infty$ partial regularity of the singular set in the obstacle problem
Franceschini, Federico
Zatoń, Wiktoria
Analysis of PDEs
We show that the singular set $Σ$ in the classical obstacle problem can be locally covered by a $C^\infty$ hypersurface, up to an "exceptional" set $E$, which has Hausdorff dimension at most $n-2$ (countable, in the $n=2$ case). Outside this exceptional set, the solution admits a polynomial expansion of arbitrarily large order. We also prove that $Σ\setminus E$ is extremely unstable with respect to monotone perturbations of the boundary datum. We apply this result to the planar Hele-Shaw flow, showing that the free boundary can have singular points for at most countable many times.
title $C^\infty$ partial regularity of the singular set in the obstacle problem
topic Analysis of PDEs
url https://arxiv.org/abs/2102.00923