On non-definite Sturm–Liouville problems with two turning points

摘要

This is an inaugural study of the Dirichlet problem associated with a regular non-definite Sturm–Liouville equation in the case of two turning points. We give a priori lower bounds on the Richardson numbers associated with this problem thereby complementing pioneering results by Atkinson and Jabon [4] in the one turning point case.