A Sharp Bound for the Ratio of the First Two Eigenvalues of Dirichlet Laplacians and Extensions

Abstract

Mark S. Ashbaugh, Rafael D. Benguria, A Sharp Bound for the Ratio of the First Two Eigenvalues of Dirichlet Laplacians and Extensions, Annals of Mathematics, Second Series, Vol. 135, No. 3 (May, 1992), pp. 601-628