Chen, Jiecheng; Li, Jiayu A note on eigenvalues. (English) Zbl 0703.53038 Chin. Sci. Bull. 35, No. 7, 536-540 (1990). Let M be a simply connected complete Riemannian manifold with sectional curvature \(K_ M\). Yau conjectured that if \(-k^ 2_ 2\leq K_ M\leq - k^ 2_ 1<0,\) then M has no \(L^ 2\) eigenvalues. The authors construct a counter example to this conjecture. Let \(0\leq k_ 1<k_ 2<\infty\). The authors construct a spherically symmetric metric \(ds^ 2=dr^ 2+f(r)^ 2d\theta^ 2\) on \(M=R^ n\) such that (1) \(-k^ 2_ 2\leq K_ M\leq -k^ 2_ 1\), (2) M has \(L^ 2\) eigenvalues. Reviewer: P.Gilkey Cited in 1 Document MSC: 53C20 Global Riemannian geometry, including pinching 58J50 Spectral problems; spectral geometry; scattering theory on manifolds Keywords:sectional curvature; counter example; \(L^ 2\) eigenvalues PDFBibTeX XMLCite \textit{J. Chen} and \textit{J. Li}, Chin. Sci. Bull. 35, No. 7, 536--540 (1990; Zbl 0703.53038)