Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Geometrical Well Posed Systems for the Einstein Equations   We show that, given an arbitrary shift, the lapse $N$ can be chosen so that
the extrinsic curvature $K$ of the space slices with metric $\overline g$ in
arbitrary coordinates of a solution of Einstein's equations satisfies a
quasi-linear wave equation. We give a geometric first order symmetric
hyperbolic system verified in vacuum by $\overline g$, $K$ and $N$. We show
that one can also obtain a quasi-linear wave equation for $K$ by requiring $N$
to satisfy at each time an elliptic equation which fixes the value of the mean
extrinsic curvature of the space slices.

27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
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The categories of this paper are: q-fin
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The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio