Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Penrose inequality   The purpose of this letter is to point out an argument which may ultimately
lead to a rigorous proof of the Penrose inequality in the general case. The
argument is a variation of Geroch's original proposal for a proof of the
positive energy theorem which was later adapted by Jang and Wald to apply to
initial data sets containing apparent horizons. The new input is to dispense
with the a priori restriction to an initial data set and to use the
four-dimensional structure of spacetime in an essential way.

32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph