# Some short questions about mathematics

1. May 2, 2007

### haushofer

Hi, I have 2 little questions and hope to find some clarity here. It concerns some mathematics.

1) Is the variation of the metric again a tensor? I have the suspicion that it's not, because i would say that it doesn't transform like one. How can i get a sensible expression then for the covariant derivative of the variation of the metric? I need this to calculate the variation of the Riemanntensor, induced by a diffeomorphism multiplied by some test function.

2) I have the idea that I don't quite understand Stoke's theorem. Does it only apply for covariant divergences, or also for partial derivatives and/or exterior derivatives? I'm a little confused here :( I need this to rewrite the variation of an action.

Thanks in forward,

Haus.