Abstract
We provide a thorough description of the free boundary for the lower dimensional obstacle problem in \({\mathbb{R}^{n+1}}\) up to sets of null \({\mathcal{H}^{n-1}}\) measure. In particular, we prove
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(i)
local finiteness of the (n−1)-dimensional Hausdorff measure of the free boundary,
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(ii)
\({\mathcal{H}^{n-1}}\)-rectifiability of the free boundary,
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(iii)
classification of the frequencies up to a set of Hausdorff dimension at most (n−2) and classification of the blow-ups at \({\mathcal{H}^{n-1}}\) almost every free boundary point.
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Change history
04 July 2018
One of the propositions of the paper on the classification of homogeneous solutions was found to be incorrect.
References
Almgren, Jr. F.J.: Almgren's Big Regularity Paper. World Scientific Monograph Series in Mathematics, 1. World Scientific Publishing Co., Inc., River Edge, NJ, 2000
Ambrosio, L., Fusco, N., Pallara, D.: Functions of Bounded Variation and Free Discontinuity Problems. Oxford Mathematical Monographs. The Clarendon Press, Oxford University Press, New York (2000)
Andersson, J.: Optimal regularity for the Signorini problem and its free boundary. Invent. Math. 204(1), 1–82 (2016)
Athanasopoulos, I., Caffarelli, L.A.: Optimal regularity of lower dimensional obstacle problems. Zap. Nauchn. Sem. S.-Peterburg. Otdel. Mat. Inst. Steklov. (POMI) 310, 49–66, 226 (2004) (translation in J. Math. Sci. (N. Y.), 132 2006, no. 3, 274–284).
Athanasopoulos, I., Caffarelli, L.A., Salsa, S.: The structure of the free boundary for lower dimensional obstacle problems. Am. J. Math. 130(2), 485–498 (2008)
Azzam, J., Tolsa, X.: Characterization of \(n\)-rectifiability in terms of Jones' square function: part II. Geom. Funct. Anal. 25(5), 1371–1412 (2015)
Barrios, B., Figalli, A., Ros-Oton, X.: Global regularity for the free boundary in the obstacle problem for the fractional Laplacian. Am. J. Math. (2017) (in press)
Caffarelli, L.A.: The regularity of free boundaries in higher dimensions. Acta Math. 139(3–4), 155–184 (1977)
Caffarelli, L.A.: Further regularity for the Signorini problem. Commun. Partial Differ. Equ. 4, 1067–1075 (1979)
Caffarelli, L.A.: The obstacle problem revisited. J. Fourier Anal. Appl. 4(4–5), 383–402 (1998)
Caffarelli, L.A., Silvestre, L.: An extension problem related to the fractional Laplacian. Commun. Partial Differ. Equ. 32(7–9), 1245–1260 (2007)
Caffarelli, L.A., Salsa, S., Silvestre, L.: Regularity estimates for the solution and the free boundary of the obstacle problem for the fractional Laplacian. Invent. Math. 171(2), 425–461 (2008)
David, G., Toro, T.: Reifenberg parameterizations for sets with holes. Mem. Am. Math. Soc. 215(1012), vi+102 (2012)
De Silva, D., Savin, O.: \(C^\infty \) regularity of certain thin free boundaries. Indiana Univ. Math. J. 64(5), 1575–1608 (2015)
De Lellis, C., Spadaro, E.: Regularity of area minimizing currents III: blow-up. Ann. Math. (2) 183(2), 577–617 (2016)
De Lellis, C., Marchese, A., Spadaro, E., Valtorta, D.: Rectifiability and Upper Minkowski Bounds for Singularities of Harmonic Q-Valued Maps. Comment. Math. Helv. (To appear)
Fabes, E., Kenig, C., Serapioni, R.: The local regularity of solutions of degenerate elliptic equations. Commun. Partial Differ. Equ. 7(1), 77–116 (1982)
Focardi, M., Gelli, M.S., Spadaro, E.: Monotonicity formulas for obstacle problems with Lipschitz coefficients. Calc. Var. Partial Differ. Equ. 54(2), 1547–1573 (2015)
Focardi, M., Geraci, F., Spadaro, E.: The classical obstacle problem for nonlinear variational energies. Nonlinear Anal. 154, 7187 (2017)
Focardi, M., Geraci, F., Spadaro, E.: Quasi-monotonicity formulas for classical obstacle problems with Sobolev coefficients and applications (To appear)
Focardi, M., Marchese, A., Spadaro, E.: Improved estimate of the singular set of Dir-minimizing Q-valued functions via an abstract regularity result. J. Funct. Anal. 268(11), 3290–3325 (2015)
Focardi, M., Spadaro, E.: An epiperimetric inequality for the fractional obstacle problem. Adv. Differ. Equ. 21(1–2), 153–200 (2016)
Focardi,M., Spadaro, E.: How a minimal surface leaves a thin obstacle (To appear)
Focardi, M., Spadaro, E.: Rectifiability of the free boundary for the fractional obstacle problem (To appear)
Frehse, J.: Two-dimensional variational problems with thin obstacles. Math. Z. 143, 279–288 (1975)
Frehse, J.: On Signorini's problem and variational problems with thin obstacles. Ann. Scuola Norm. Sup. Pisa 4, 343–362 (1977)
Garofalo, N., Petrosyan, A.: Some new monotonicity formulas and the singular set in the lower dimensional obstacle problem. Invent. Math. 177(2), 415–461 (2009)
Garofalo, N., Petrosyan, A., Pop, C., Smit Vega Garcia, M.: Regularity of the free boundary for the obstacle problem for the fractional Laplacian with drift. Ann. Inst. H. Poincar Anal. Non Linéaire, 34(3), 533–570 (2017)
Garofalo, N., Ros-Oton,X.: Structure and regularity of the singular set in the obstacle problem for the fractional Laplacian. arXiv:1704.00097
Geraci, F.: The Classical Obstacle Problem for Nonlinear Variational Energies and Related Problems. Ph.D. thesis, University of Firenze, 2016
Geraci, F.: An Epiperimetric Inequality for the Lower Dimensional Obstacle Problem. arXiv:1709.00996.
Hopf, E.: Über den funktionalen, insbesondere den analytischen Charakter der Lösungen elliptischer Differentialgleichungen zweiter Ordnung. (German). Math. Z. 34(1), 194–233 (1932)
Jones, P.: Rectifiable sets and the traveling salesman problem. Invent. Math. 102(1), 1–15 (1990)
Kinderlehrer, D.: The smoothness of the solution of the boundary obstacle problem. J. Math. Pures Appl. 60, 193–212 (1981)
Koch, H., Petrosyan, A., Shi, W.: Higher regularity of the free boundary in the elliptic Signorini problem. Nonlinear Anal. 126, 3–44 (2015)
Krummel, B., Wickramasekera, N.: Fine Properties of Branch Point Singularities: Two-Valued Harmonic Functions. arXiv:1311.0923
Krummel, B., Wickramasekera, N.: Fine Properties of Branch Point Singularities: Dirichlet Energy Minimizing Multi-Valued Functions. arXiv:1711.06222
Monneau, R.: On the number of singularities for the obstacle problem in two dimensions. J. Geom. Anal. 13(2), 359–389 (2003)
Naber, A., Valtorta, D.: Rectifiable–Reifenberg and the regularity of stationary and minimizing harmonic maps. Ann. Math. (2) 185(1), 131–227 (2017)
Naber, A., Valtorta, D.: The Singular Structure and Regularity of Stationary and Minimizing Varifolds. arXiv:1505.03428
Olver, F.W.J., Olde Daalhuis, A.B., Lozier, D.W., Schneider, B.I., Boisvert, R.F., Clark, C.W., Miller, B.R., Saunders, B.V. (eds.): NIST Digital Library of Mathematical Functions. http://dlmf.nist.gov/, Release 1.0.14 of 2016-12-21
Ros-Oton, X., Serra, J.: Boundary regularity for fully nonlinear integro-differential equations. Duke Math. J. 165(11), 2079–2154 (2016)
Silvestre, L.: Regularity of the obstacle problem for a fractional power of the Laplace operator. Commun. Pure Appl. Math. 60(1), 67–112 (2007)
Uraltseva, N.N.: Hölder continuity of gradients of solutions of parabolic equations with boundary conditions of Signorini type. Dokl. Akad. Nauk SSSR 280, 563–565 (1985)
Uraltseva, N.N.: On the regularity of solutions of variational inequalities. (Russian) Uspekhi Mat. Nauk 42(6(258)), 151–174, 248 (1987)
Weiss, G.S.: A homogeneity improvement approach to the obstacle problem. Invent. Math. 138(1), 23–50 (1999)
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Focardi, M., Spadaro, E. On the Measure and the Structure of the Free Boundary of the Lower Dimensional Obstacle Problem. Arch Rational Mech Anal 230, 125–184 (2018). https://doi.org/10.1007/s00205-018-1242-4
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DOI: https://doi.org/10.1007/s00205-018-1242-4