Physics – Physics and Society
Scientific paper
2012-01-05
Physics
Physics and Society
Submitted to New Journal of Physics
Scientific paper
Due to the increasing popularity of collaborative tagging systems, the research on tagged networks, hypergraphs, ontologies, folksonomies and other related concepts is becoming an important interdisciplinary topic with great actuality and relevance for practical applications. In most collaborative tagging systems the tagging by the users is completely "flat", while in some cases they are allowed to define a shallow hierarchy for their own tags. However, usually no overall hierarchical organisation of the tags is given, and one of the interesting challenges of this area is to provide an algorithm generating the ontology of the tags from the available data. In contrast, there are also other type of tagged networks available for research, where the tags are already organised into a directed acyclic graph (DAG), encapsulating the "is a sub-category of" type of hierarchy between each other. In this paper we study how this DAG affects the statistical distribution of tags on the nodes marked by the tags in various real networks. We analyse the relation between the tag-frequency and the position of the tag in the DAG in two large sub-networks of the English Wikipedia and a protein-protein interaction network. We also study the tag co-occurrence statistics by introducing a 2d tag-distance distribution preserving both the difference in the levels and the absolute distance in the DAG for the co-occurring pairs of tags. Our most interesting finding is that the local relevance of tags in the DAG, (i.e., their rank or significance as characterised by, e.g., the length of the branches starting from them) is much more important than their global distance from the root. Furthermore, we also introduce a simple tagging model based on random walks on the DAG, capable of reproducing the main statistical features of tag co-occurrence.
Palla Gergely
Pollner Peter
Tibely Gergely
Vicsek Tamás
No associations
LandOfFree
Ontologies and tag-statistics does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Ontologies and tag-statistics, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ontologies and tag-statistics will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-609351