Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Matrix-Forest Theorem and Measuring Relations in Small Social Groups   We propose a family of graph structural indices related to the Matrix-forest
theorem. The properties of the basic index that expresses the mutual
connectivity of two vertices are studied in detail. The derivative indices that
measure "dissociation," "solitariness," and "provinciality" of vertices are
also considered. A nonstandard metric on the set of vertices is introduced,
which is determined by their connectivity. The application of these indices in
sociometry is discussed.

16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an