Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Dark Matter problem   In these notes I will briefly summarize our knowledge about the dark matter
problem, and emphasize the corresponding dynamical aspects. This covers a wide
area of research, so I have been selective, and have concentrated on the
subject of dark matter in nearby galaxies, in particular spirals.

32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph