Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Coteries, Social Circles and Hamlets Close Communities: A Study of
  Acquaintance Networks   In the analysis of social networks many relatively loose and heuristic
definitions of 'community' abound. In this paper the concept of closely knit
communities is studied as defined by the property that every pair of its
members are neighbors or has at least one common neighbor, where the
neighboring relationship is based on some more or less durable and stable
acquaintance or contact relation. In this paper these are studied in the form
of graphs or networks of diameter two (2-clubs). Their structure can be
characterized by investigating shortest spanning trees and girth leading to a
typology containing just three or, in combination, six types of close
communities.

35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat