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Need to define projectives on any manifold first then specialise to spacetimes. ---Mpatel (talk) 13:12, August 28, 2005 (UTC)

Well, you need something that fixes the geodesic structure, so generalization to (semi) Riemannian manifolds is straight forward, done. [melli]146.186.134.176 (talk) 00:42, 15 February 2008 (UTC)Reply

Given a vector field ${\displaystyle X=(X^{a})}$ on a semi Riemannian manifold, what is ${\displaystyle X_{ab}}$? Is it related to your ${\displaystyle h_{ab}}$ or ${\displaystyle F_{ab}}$? if it were just ${\displaystyle X_{a;b}}$ then ${\displaystyle \psi }$ would be 0, right? [melli] 146.186.134.176 (talk) 00:33, 15 February 2008 (UTC)Reply

I hope the dimensional estimates for the algebras (which are clearly local) do not depend on the signature of the metric. [melli]146.186.134.176 (talk) 01:06, 15 February 2008 (UTC)Reply