摘要

An infinite-dimensional Evans function E(lambda) and a stability index theorem are developed for the elliptic eigenvalue problem in a bounded domain Omega subset of R-m. The number of zero points of the Evans function in a bounded, simply connected complex domain D is shown to be equal to the number of eigenvalues of the corresponding elliptic operator in D. When the domain Omega is star-shaped, an associated unstable bundle epsilon(D) based on D is constructed, and the first Chem number of epsilon(D) also gives the number of eigenvalues of the elliptic operator inside D.