?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Measuring+Similarity+in+Large-Scale+Folksonomies&rft.creator=Quattrone%2C+Giovanni&rft.creator=Ferrara%2C+Emilio&rft.creator=De+Meo%2C+Pasquale&rft.creator=Capra%2C+Licia&rft.subject=Artificial+Intelligence&rft.description=Social+(or+folksonomic)+tagging+has+become+a+very+popular+way+to+describe+content+within+Web+2.0+websites.+Unlike%0D%0Ataxonomies%2C+which+overimpose+a+hierarchical+categorisation+of+content%2C+folksonomies+enable+end-users+to+freely+create+and+choose+the+categories+(in+this+case%2C+tags)+that+best%0D%0Adescribe+some+content.+However%2C+as+tags+are+informally+de-%0D%0A%EF%AC%81ned%2C+continually+changing%2C+and+ungoverned%2C+social+tagging%0D%0Ahas+often+been+criticised+for+lowering%2C+rather+than+increasing%2C+the+ef%EF%AC%81ciency+of+searching%2C+due+to+the+number+of+synonyms%2C+homonyms%2C+polysemy%2C+as+well+as+the+heterogeneity+of%0D%0Ausers+and+the+noise+they+introduce.+To+address+this+issue%2C+a%0D%0Avariety+of+approaches+have+been+proposed+that+recommend%0D%0Ausers+what+tags+to+use%2C+both+when+labelling+and+when+looking+for+resources.+As+we+illustrate+in+this+paper%2C+real+world%0D%0Afolksonomies+are+characterized+by+power+law+distributions%0D%0Aof+tags%2C+over+which+commonly+used+similarity+metrics%2C+including+the+Jaccard+coef%EF%AC%81cient+and+the+cosine+similarity%2C+fail%0D%0Ato+compute.+We+thus+propose+a+novel+metric%2C+speci%EF%AC%81cally%0D%0Adeveloped+to+capture+similarity+in+large-scale+folksonomies%2C%0D%0Athat+is+based+on+a+mutual+reinforcement+principle%3A+that+is%2C%0D%0Atwo+tags+are+deemed+similar+if+they+have+been+associated+to%0D%0Asimilar+resources%2C+and+vice-versa+two+resources+are+deemed%0D%0Asimilar+if+they+have+been+labelled+by+similar+tags.+We+offer+an+ef%EF%AC%81cient+realisation+of+this+similarity+metric%2C+and+assess+its+quality+experimentally%2C+by+comparing+it+against+cosine+similarity%2C+on+three+large-scale+datasets%2C+namely+Bibsonomy%2C+MovieLens+and+CiteULike.&rft.date=2011&rft.type=Conference+Paper&rft.type=PeerReviewed&rft.format=application%2Fpdf&rft.identifier=http%3A%2F%2Fcogprints.org%2F7646%2F1%2Fseke2011-QuattroneGiovanni.pdf&rft.identifier=++Quattrone%2C+Giovanni+and+Ferrara%2C+Emilio+and+De+Meo%2C+Pasquale+and+Capra%2C+Licia++(2011)+Measuring+Similarity+in+Large-Scale+Folksonomies.++%5BConference+Paper%5D+++++&rft.relation=http%3A%2F%2Fcogprints.org%2F7646%2F