Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Maximum Principle of the Navier-Stokes Equation   In the work of Navier-Stokes (NSE) equation, derived a nonlinear parabolic
equation for kinetic energy density, and identified an important property of
this equation - the maximum principle. The latter shows the validity of the
maximum principle and the NSE. On the basis of what, the unique solvability of
the weak and the existence of strong solutions for NSE was proved wholly in
time t \in [0, T], \forall T < \infty.

6
The categories of this paper are: astro-ph
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
4
The categories of this paper are: cond-mat
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int