Polygons and multi-product of eigenfunctions

Emmett L. Wyman, Yakun Xi, Yi Zhang

Let $M$ be a compact Riemannian manifold without boundary, with $L^2$-normalized Laplace-Beltrami eigenfunctions $\{e_j{\}}_j$, which satisfy ${\Delta }_g{e}_j=-{\lambda }_j^2{e}_j$. We study the fol…