Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Matroids Hitting Sets and Unsupervised Dependency Grammar Induction   This paper formulates a novel problem on graphs: find the minimal subset of
edges in a fully connected graph, such that the resulting graph contains all
spanning trees for a set of specifed sub-graphs. This formulation is motivated
by an un-supervised grammar induction problem from computational linguistics.
We present a reduction to some known problems and algorithms from graph theory,
provide computational complexity results, and describe an approximation
algorithm.

37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ