Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Diffeomorphism symmetry in quantum gravity models   We review and discuss the role of diffeomorphism symmetry in quantum gravity
models. Such models often involve a discretization of the space-time manifold
as a regularization method. Generically this leads to a breaking of the
symmetries to approximate ones, however there are incidences in which the
symmetries are exactly preserved. Both kind of symmetries have to be taken into
account in covariant and canonical theories in order to ensure the correct
continuum limit. We will sketch how to identify exact and approximate
symmetries in the action and how to define a corresponding canonical theory in
which such symmetries are reflected as exact and approximate constraints.

22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con