Metrics with homogeneous geodesics on flag manifolds
A geodesic of a homogeneous Riemannian manifold is called homogeneous if it is an orbit of an one-parameter subgroup of . In the case when is a naturally reductive space, that is the -invariant metric is defined by some non degenerate biinvariant symmetric bilinear form , all geodesics of are homogeneous. We consider the case when is a flag manifold, i.eȧn adjoint orbit of a compact semisimple Lie group , and we give a simple necessary condition that admits a non-naturally reductive...