Gradient estimates for the ground state Schrödinger eigenfunction and applications. (Q5956424)

In this paper the authors give a simple and short proof of the sharp lower bound for the spectral gap of the Dirichlet Laplacian in \( \Omega \) in the case that \( \Omega \) is a planar convex domain which is simmetric with respect to each coordinate axes. The proof uses maximumprinciple argument.