convexity estimate;
superharmonicity;
maximum principle;
torsion problem;
LEVEL SETS;
D O I:
10.1007/s11425-021-1957-7
中图分类号:
O29 [应用数学];
学科分类号:
070104 ;
摘要:
In this paper, for the solution of the torsion problem about the equation Delta u = -2 with homogeneous Dirichlet boundary conditions in a bounded convex domain in R-n, we find a superharmonic function which implies the strict concavity of u(1/2) and give some convexity estimates. It is a generalization of Makar-Limanov's result (Makar-Limanov (1971)) and Ma-Shi-Ye's result (Ma et al. (2012)).