In the study of concavity properties of positive solutions to nonlinear elliptic partial differential equations the diffusion and the nonlinearity are typically independent of the space variable. In this paper we obtain new results aiming to get almost concavity results for a relevant class of anisotropic semilinear elliptic problems with spatially dependent source and diffusion.
N.Almousa, J.Assettini, M.Gallo and M.Squassina, Concavity properties for quasilinear equations and optimality remarks, Differential Integral Equations (2023), to appear.
2.
W.Borrelli, S.Mosconi and M.Squassina, Concavity properties for solutions to p-Laplace equations with concave nonlinearities, Adv. Calc. Var. (2022). doi:10.1515/acv-2021-0100.
3.
H.J.Brascamp and E.H.Lieb, On extensions of the Brunn–Minkowski and Prékopa–Leindler theorems, including inequalities for log concave functions, and with an application to the diffusion equation, J. Funct. Anal.22 (1976), 366–389. doi:10.1016/0022-1236(76)90004-5.
4.
C.Bucur and M.Squassina, Approximate convexity principles and applications to PDEs in convex domains, Nonlinear Analysis192 (2020), Article ID 111661.
5.
B.Gidas, W.-M.Ni and L.Nirenberg, Symmetry and related properties via the maximum principle, Commun. Math. Phys.68 (1979), 209–243. doi:10.1007/BF01221125.
6.
D.Gilbarg and N.Trudinger, Elliptic Partial Differential Equations of Second Order, Springer Verlag, 1977.
7.
J.M.Gomes, Sufficient conditions for the convexity of the level sets of ground-state solutions, Arch. Math.88 (2007), 269–278. doi:10.1007/s00013-006-1963-8.
8.
A.Henrot, C.Nitsch, P.Salani and C.Trombetti, Optimal concavity of the torsion function, J. Optim. Theory Appl.178 (2018), 26–35. doi:10.1007/s10957-018-1302-9.
9.
D.H.Hyers and S.M.Ulam, Approximately convex functions, Proc. Amer. Math. Soc.3 (1952), 821–828. doi:10.1090/S0002-9939-1952-0049962-5.
10.
B.Kawohl, Rearrangements and Convexity of Level Sets in PDE, Lecture Notes in Math., Vol. 1150, Springer-Verlag, Heidelberg, 1985.
11.
B.Kawohl, When are solutions to nonlinear elliptic boundary value problems convex?, Comm. Partial Differential Equations10 (1985), 1213–1225. doi:10.1080/03605308508820404.
12.
A.U.Kennington, Power concavity and boundary value problems, Indiana Univ. Math. J.34 (1985), 687–704. doi:10.1512/iumj.1985.34.34036.
13.
N.J.Korevaar, Convex solutions to nonlinear elliptic and parabolic boundary value problems, Indiana Univ. Math. J.32(4) (1983), 603–614. doi:10.1512/iumj.1983.32.32042.