Abstract
We extend a result of John Lewis [L] by showing that if a doubling metric measure space supports a (1,q 0)-Poincaré inequality for some 1<q 0<p, then every uniformlyp-fat set is uniformlyq-fat for someq<p. This bootstrap result implies the Hardy inequality for Newtonian functions with zero boundary values for domains whose complements are uniformly fat. While proving this result, we also characterize positive Radon measures in the dual of the Newtonian space using the Wolff potential and obtain an estimate for the oscillation ofp-harmonic functions andp-energy minimizers near a boundary point.
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References
[Bj] J. Björn,Boundary continuity for quasi-minimizers on metric spaces, Preprint (2000).
[C] J. Cheeger,Differentiability of Lipschitz functions on measure spaces, Geom. Funct. Anal.9 (1999), 428–517.
[FHK] B. Franchi, P. Hajłasz and P. Koskela,Definitions of Sobolev classes on metric spaces, Ann. Inst. Fourier (Grenoble)49 (1999), 1903–1924.
[HaK] P. Hajłasz and P. Koskela,Sobolev met Poincaré, Mem. Amer. Math. Soc.145 (2000).
[HW] L. I. Hedberg and T. Wolff,Thin sets in nonlinear potential theory, Ann. Inst. Fourier (Grenoble)33 (1983), 161–187.
[HKM] J. Heinonen, T. Kilpeläinen and O. Martio,Nonlinear Potential Theory of Degenerate Elliptic Equations, Oxford University Press, Oxford, 1993.
[HeK] J. Heinonen and P. Koskela,Quasiconformal maps in metric spaces with controlled geometry, Acta Math.181 (1998), 1–61.
[KaSh] S. Kallunki and N. Shanmugalingam,Modulus and continuous capacity, Ann. Acad. Sci. Fenn. Math. (to appear).
[KL] J. Kinnunen and V. Latvala,Lebesgue points for Sobolev functions on metric measure spaces, Preprint (2000).
[KM1] J. Kinnunen and O. Martio,The Sobolev capacity on metric spaces, Ann. Acad. Sci. Fenn. Math.21 (1996), 367–382.
[KM2] J. Kinnunen and O. Martio,Hardy’s inequalities for Sobolev functions, Math. Res. Lett.4 (1997), 489–500.
[KiSh] J. Kinnunen and N. Shanmugalingam,Quasi-minimizers on metric spaces, Preprint (1999).
[KMc] P. Koskela and P. MacManus,quasiconformal mappings and Sobolev spaces, Studia Math.131 (1998), 1–17.
[Ku] A. Kufner,Weighted Sobolev Spaces, Wiley, New York, 1985
[L] J. Lewis,Uniformly fat sets, Trans. Amer. Math. Soc.308 (1988), 177–196.
[LM] P. Lindqvist and O. Martio,Two theorems of N. Wiener for solutions of quasilinear elliptic equations, Acta Math.155 (1985), 153–171.
[Li] J.-L. Lions,Quelques méthodes de résolution des problémes aux limites non linéaires, Dunod, Paris, 1969.
[M1] V. Maz’ya.Regularity at the boundary of solutions of elliptic equations and conformal mapping, Dokl. Akad. Nauk SSSR150:6 (1963), 1297–1300 (in Russian); English transl.: Soviet Math. Dokl.4: 5 (1963), 1547–1551.
[M2] V. Maz’ya,On the continuity at a boundary point of solutions of quasi-linear elliptic equations, Vestnik Leningrad. Univ.25: 13 (1970), 42–55 (in Russian); English transl.: Vestnik Leningrad Univ. Math.3 (1976), 225–242.
[Mi] P. Mikkonen,On the Wolff potential and quasilinear elliptic equations involving measures, Ann. Acad. Sci. Fenn., Math. Dissertationes104 (1996).
[MV] V. Miklyukov and M. Vuorinen,Hardy’s inequality for W 1,p0 -functions on Riemannian manifolds, Proc. Amer. Math. Soc.127 (1999), 2745–2754.
[Ru1] W. Rudin,Real and Complex Analysis, 3rd edn., McGraw-Hill, New York, 1987.
[Ru2] W. Rudin,Functional Analysis, 2nd edn., McGraw-Hill, New York, 1991.
[Se] S. Semmes,Finding curves on general spaces through quantitative, topology with applications to Sobolev and Poincaré inequalities. Selecta Math.2 (1996) 155–295.
[Sh1] N. Shanmugalingam,Newtonian spaces: An extension of Sobolev spaces to metric measure spaces, Rev. Mat. Iberoamericana16 (2000), 243–279.
[Sh2] N. Shanmugalingam,Harmonic functions on metric spaces, Illinois J. Math. (to appear).
[Wa] A. Wannebo,Hardy inequalities, Proc. Amer. Math. Soc.109 (1990), 85–95.
[Wi] N. Wiener,The Dirichlet problem, J. Math. Phys.3 (1924), 127–146.
[Yo] K. Yosida,Functional Analysis, Springer-Verlag, Berlin-New York, 1980.
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Björn, J., MacManus, P. & Shanmugalingam, N. Fat sets and pointwise boundary estimates forp-harmonic functions in metric spaces. J. Anal. Math. 85, 339–369 (2001). https://doi.org/10.1007/BF02788087
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DOI: https://doi.org/10.1007/BF02788087