Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Middlemen and Contestation in Directed Networks   This paper studies critical nodes or "middlemen" that intermediate flows in a
directed network. The contestability of a node is introduced as a network
topological concept of competitiveness meaning that an intermediary's role in
the brokering of flows in the network can be substituted by a group of other
nodes. We establish the equivalence of uncontested intermediaries and
middlemen.
  The notion of node contestability gives rise to a measure that quantifies the
control exercised by a middleman in a network. We present a comparison of this
middleman centrality measures with relevant, established network centrality
measures. Furthermore, we provide concepts and measures expressing the
robustness of a middleman as the number of links or nodes that have to be added
to or removed from the network to nullify the middleman's power.
  We use these concepts to identify and measure middleman power and robustness
in two empirical networks: Krackhardt's advice network of managers in a medium
sized corporation and the well-known Florentine marriage network as a proxy of
power brokerage between houses in Renaissance Florence.

5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom