AN OBATA SINGULAR THEOREM FOR STRATIFIED SPACES

作者：Mondello Ilaria^*

来源：Transactions of the American Mathematical Society, 2018, 370(6): 4147-4175.

DOI：10.1090/tran/7105

Consider a stratified space with a positive Ricci lower bound on the regular set and no cone angle larger than 2 pi. For such stratified space we know that the first non-zero eigenvalue of the Laplacian is larger than or equal to the dimension. We prove here an Obata rigidity result when the equality is attained: the lower bound of the spectrum is attained if and only if the stratified space is isometric to a spherical suspension. Moreover, we show that the diameter is at most equal to pi, and it is equivalent for the diameter to be equal to p and for the first non-zero eigenvalue of the Laplacian to be equal to the dimension. We finally give a consequence of these results related to the Yamabe problem. Consider an Einstein stratified space without cone angles larger than 2 pi: if there is a metric conformal to the Einstein metric and with constant scalar curvature, then it is an Einstein metric as well. Furthermore, if its conformal factor is not a constant, then the space is isometric to a spherical suspension.

• 出版日期2018-6