G. Alessandrini, NODAL LINES OF EIGENFUNCTIONS OF THE FIXED MEMBRANE PROBLEM IN GENERAL CONVEX DOMAINS, Commentarii mathematici helvetici, 69(1), 1994, pp. 142-154
We describe the boundary behavior of the nodal lines of eigenfunctions
of the fixed membrane problem in convex, possibly nonsmooth, domains.
This result is applied to the proof of Payne's conjecture on the noda
l line of second eigenfunctions [P1], by removing the Cinfinity smooth
ness assumption which is present in the original proof of Melas [M].