As we all know, for a Riemannian manifold $(M,g)$, there exists a unique torsion free connection $\Delta_g$, \nabla_g$, the Levi-Civita connection, that is compatible witht metric.
I was wondering if one can reverse this situation: Given a manifold with $M$ with connection $\Delta$, \nabla$, when does there exist a Riemannian metric $g$ for which $\Delta$ \nabla$ is the Levi-Civita connection.
If this were true for complex projective manifolds it would make me be very happy.

