

![0_image_0.png](0_image_0.png)

very likely that a number of co-occurrences of a given concept pair is very low, compared to that of individual one. Consequently, a chance that one concept
"subsumes" another one is very low. From our dataset, we found that a relation between china and countri is not induced by the subsumption approach.

In particular, a number of their co-occurrences is just 6 compared to their frequency 596 and 256 respectively, and consequently neither is judged to subsume the other. In our approach, we instead consider explicit relations of concepts, which will not suffer from this issue.

## 5 Conclusion

The social Web sites allow users to contribute content and also provide tools to help them manage content by annotating it with descriptive tags, and more recently, with semantic relations. By making large amount of such metadata available, social Web sites enable researchers to empirically study how humans organize knowledge, and also to learn a common classification system, a folksonomy, from the data. This paper describes a statistical approach to aggregating large number of simple broader/narrower relations specified by different users into a common, deeper folksonomy. The broader/narrow relations we used for