Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: ACE Bounds; SEMs with Equilibrium Conditions   Discussion of "Instrumental Variables: An Econometrician's Perspective" by
Guido W. Imbens [arXiv:1410.0163].

33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom