Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New solvable problems in the dynamics of a rigid body about a fixed
  point in a potential field   We determine the general form of the potential of the problem of motion of a
rigid body about a fixed point, which allows the angular velocity to remain
permanently in a principal plane of inertia of the body. Explicit solution of
the problem of motion is reduced to inversion of a single integral. A
several-parameter generalization of the classical case due to Bobylev and
Steklov is found. Special cases solvable in elliptic and ultraelliptic
functions of time are discussed.

23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
1
The categories of this paper are: cs