Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the three-dimensional magnetohydrodynamics system in
  scaling-invariant spaces   We study the criterion for the velocity and magnetic vector fields that solve
the three-dimensional magnetohydrodynamics system, given any initial data
sufficiently smooth, to experience a finite-time blowup. Following the work of
[12] and making use of the structure of the system, we obtain a criterion that
is imposed on the magnetic vector field and only one of the three components of
the velocity vector field, both in scaling-invariant spaces.

12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
16
The categories of this paper are: stat
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ