Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On some fundamental problems of the theory of gravitation   Cosmological observations indicate that the Einstein equation may not be
entirely correct to describe gravity.
  However, numerous modifications of these equations usually do not affect
foundations of the theory. In this paper two important issue that lead to a
substantial revision of the theory are considered : 1. The significance of
relativity of space-time geometry with respect to measuring instruments for
theory of gravitation. 2. The gauge transformations of the field variables in
correct theory of gravitation.

12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
7
The categories of this paper are: hep-th
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat