2 problems

A Riemannian manifold $(M,\langle\,\ \rangle)$ is globally Osserman if the eigenvalues of its Jacobi operator $R_u$ are independent of both the unit tangent vector $u\in M_x$ and t…

Osserman's conjecture. If $(M,g)$ is an Osserman metric, then the group of local isometries acts transitively on $S(M)$; equivalently, $(M,g)$ is flat or locally rank-one symmetric…