Community-Contributed Media Collections: Knowledge at Our Fingertips - Community-Built Databases: Research and Development - page 27

Fig. 2.1 Taxonomy of user-contributed media collection features
folksonomy models [ 14 ], and analyzing the properties of information spreading
through communities [ 15 ].
In this section, we discuss diverse works analyzing the community nature and
the media collection features of Flickr, YouTube, and Wikipedia. We propose a
taxonomy, shown in Fig. 2.1 , to categorize the discussed works in three main topics:
(a) social networks (see Sect. 2.3.1 ), (b) media content distribution (see Sect. 2.3.2 ),
and (c) semantics of media content (see Sect. 2.3.3 ). The social network topic
includes two main issues, network structure [ 5 , 13 , 16 ] and growth trend [ 17 ], while
the media content distribution topic includes lifespan of content [ 18 ] and social
popularity [ 19 , 20 ].
2.3.1 Social Networks
Social networks have been studied from two different points of views: network
structure [ 5 , 13 , 16 ] and growth trend [ 17 ], as shown in the taxonomy reported in
Fig. 2.1 . From the structure point of view, social networks are modeled by graphs
where nodes represent the users and links the friendships among users. Different
graph mining algorithms have been exploited to extract relevant and useful infor-
mation on social community structure [ 13 ].
Online social networking sites also represent a unique opportunity to study the
dynamics of social networks and the ways they grow. The growth trend (see
taxonomy in Fig. 2.1 ) in the Flickr social network has been investigated in [ 17 ].