Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Redshift drift of gravitational lensing   We investigate the effect of the redshift drift in strong gravitational
lensing. The redshift drift produces a time variation of $i)$ the apparent
position of a lensed source and $ii)$ the time delay among incoming signals
from different images. We dub these effects as angular drift and time delay
drift, respectively, and analyze their relevance in cosmology.

15
The categories of this paper are: nucl-ex
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The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
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The categories of this paper are: eess
18
The categories of this paper are: econ
3
The categories of this paper are: physics
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
1
The categories of this paper are: cs