what-when-how
In Depth Tutorials and Information
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he path between the nodes
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High degree nodes in the network
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he relative power of a node
Centrality(degree):
Degree can be considered as the relative significance of a node in
the network. he nodes can be characterized by the diferent degrees as the header,
follower, border, etc. In general, if a node is in the middle of some nodes' com-
munication route, it can be deined as the central node. he centrality of a node
can be measured by the following ways: One method is to measure the distance or
hops away from the nodes in the network. he other is to calculate the number of
a node's immediate neighbors that are one hop away from it.
In Figure 12.1 there are eight nodes and nine edges in the graph. he degree of a
given node is the number of nodes that directly connect to this node. For instance,
node 2 connects to both node 1 and node 3, so the degree of node 3 is 2. In Figure 12.1
every node can reach every other node. he distance or path between two nodes is
equal to the number of edges in the path. he shortest path for a given node to reach
other node is the
geodesicdistance
. For instance, the shortest path for node 1 to reach
node 5 is through the node 4 (two hops), that is, it is the geodesic distance.
Betweenness:
Betweenness denotes that a node is in the middle of the commu-
nication paths of the other nodes. For instance, many nodes do not communicate
with each other by the geodesic distance or shortest path. In this situation, two
measures are proposed that are based on all the paths between the nodes and any
random selected paths.
Closeness:
Closeness can be explained as a method which assumes the node
propagates the information to other nodes by using the shortest route or geodesic
distance. A function of measuring the closeness is to estimate the time for a node
to spread information to other nodes in the network.
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Figure 12.1
A graph example. (From Hussain, D. M. 2007.
Proceedings of the
Second International Conference on Availability, Reliability and Security
[April
10-13,2007].ARES.IEEEComputerSociety,Washington,DC,480-492.)
