Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Solvation force between tethered polyelectrolyte layers. A density
  functional approach
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol