Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pair Formation in a t-J Model   We have investigated the formation of bound state of two electrons in
different kind of lattices using a t-J-U model.

9
The categories of this paper are: nlin
2
The categories of this paper are: math
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
6
The categories of this paper are: astro-ph
34
The categories of this paper are: chem-ph
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga