15. The method of claim 14 , further comprising: selecting one or more of the concept terms as advertising keywords to be used in selecting candidate advertisements for participation in the online advertisement auction based on the relevance scores.
15. The method of claim 14 , further comprising: selecting one or more of the concept terms as advertising keywords to be used in selecting candidate advertisements for participation in the online advertisement auction based on the relevance scores. 17. The method of claim 15 , further comprising: filtering out concept terms that have a Term Frequency Inverse Document Frequency (TF-IDF) score that exceeds a threshold value.