Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the nonexistence of harmonic and bi-harmonic maps   In this paper, we study the existence of harmonic and bi-harmonic maps into
Riemannian manifolds admitting a conformal vector field, or a nontrivial Ricci
solitons.

12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph