Let (M,g) be a riemannian manifold with riemannian curvature R. We have d∗∇=∗∘d∇∘∗, with ∗ the Hodge operator, and d∇ the differential so that we can define:
d∗∇R∈Λ1(TM)⊗End(TM)
We define a flow over the metrics called the Riemann flow by:
∂g∂t(X,Y)=−tr((d∗∇R(X))∘(d∗∇R(Y)))
Has the Riemann flow solutions for any initial conditions?
Moreover, the Einstein-Riemann metrics are such that:
λg(X,Y)=tr((d∗∇R(X))∘(d∗∇R(Y)))
with λ a scalar.