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I do not see a contradiction here. The definition is really a set of nodes
(actors) together with a set of edges (ties) that connect pairs of actors.
The definition does not specify how these ties are distributed across the
set of actors. In addition, the set of ties can be empty, as when a group of
strangers meet. As time passes, more and more ties are formed, and the
network becomes gradually less fragmented until all nodes belong to the same
component. If you do not allow networks to be fragmented, it is difficult to
talk about the evolution of a network.

I tend to reserve the term "different network" for different social
relations (e.g., friendship and advice), or for the networks obtained by
taking separate surveys of different groups, as when I collect network data
separately within top management teams of 40 companies (ala the work of Nick
Athanassiou). The latter case could be viewed as components but we don't do
that because the respondents were not given the opportunity to report ties
between the organizations.


Steve Borgatti
Org Studies, Boston College
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>-----Original Message-----
>From: Social Networks Discussion Forum [mailto:[log in to unmask]] On
>Behalf Of Mueller-Prothmann
>Sent: Tuesday, May 03, 2005 06:30
>To: [log in to unmask]
>Subject: [SOCNET] RFC about Basic Network Definitions
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>Hi all,
>a very basic question and request for comments:
>Commonly, a social network is defined as a set of individual persons
>(actors) that are connected through social relationships. On the other
>hand, social network analysis (as an empirical method) includes models
>of isolates (single actors that are not connected to the overall
>network) or independent components (multiple actors that are connected
>but not to the main component). Concepts of isolates and independent
>components (also known as islands) are a contradiction to the above
>cited network definition. In that case, we should rather speak of
>different networks (than of one single network consisting of different
>components) or we must modify our network definition.
>Does anybody know any literature that addresses this contradiction? Or
>do you have any suggestions how to overcome it?
>All suggestions and comments are very welcome!
>Thank you! Best wishes
>Tobias Müller-Prothmann
>Freie Universitaet Berlin
>Institute for Media and Communication Studies
>Department of Information Science
>Malteserstr. 74-100
>D-12249 Berlin
>Tel. +49 (0)30 838 70854
>Fax. +49 (0)30 838 70722
>Email: mailto:[log in to unmask]
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