I hope these are not to vague questions for MO.
Is there an analog of the concept of a Riemannian metric, in algebraic geometry?
Of course, transporting things literally from the differential geometric context, we have to forget about the notion of positive definiteness, cause a bare field has no ordering. So perhaps we're looking to an algebro geometric analog of semi- Riemannian geometry.
Suppose to consider a pair $(X,g)$, where $X$ is a (perhaps smooth) variety and $g$ is a nondegenerate section of the second symmetric power of the tangent bundle (or sheaf) of $X$.
What can be said about this structure? Can some results of DG be reproduced in this context? Is there a literature about this things?