▁such ▁as ▁for ▁collabor ative ▁filtering ▁in ▁a ▁recomm ender ▁system , ▁in ▁which ▁“ similar ” ▁users ▁and ▁items ▁are ▁grouped ▁based ▁on ▁the ▁users ’ ▁prefer ences . ▁ ▁Vari ous ▁aspects ▁of ▁objects ▁can ▁be ▁used ▁to ▁determine ▁similarity , ▁usually ▁depending ▁on ▁the ▁domain ▁and ▁the ▁appropriate ▁definition ▁of ▁similarity ▁for ▁that ▁domain . ▁In ▁a ▁document ▁cor pus , ▁matching ▁text ▁may ▁be ▁used , ▁and ▁for ▁collabor ative ▁filtering , ▁similar ▁users ▁may ▁be ▁identified ▁by ▁common ▁prefer ences . ▁Sim R ank ▁is ▁a ▁general ▁approach ▁that ▁explo its ▁the ▁object - to - object ▁relationships ▁found ▁in ▁many ▁domains ▁of ▁interest . ▁On ▁the ▁Web , ▁for ▁example , ▁two ▁pages ▁are ▁related ▁if ▁there ▁are ▁hyper links ▁between ▁them . ▁A ▁similar ▁approach ▁can ▁be ▁applied ▁to ▁scientific ▁papers ▁and ▁their ▁cit ations , ▁or ▁to ▁any ▁other ▁document ▁cor pus ▁with ▁cross - reference ▁information . ▁In ▁the ▁case ▁of ▁recomm ender ▁systems , ▁a ▁user ’ s ▁preference ▁for ▁an ▁item ▁constit utes ▁a ▁relationship ▁between ▁the ▁user ▁and ▁the ▁item . ▁Such ▁domains ▁are ▁naturally ▁mode led ▁as ▁graphs , ▁with ▁nodes ▁representing ▁objects ▁and ▁edges ▁representing ▁relationships . ▁ ▁The ▁intu ition ▁behind ▁the ▁Sim R ank ▁algorithm ▁is ▁that , ▁in ▁many ▁domains , ▁similar ▁objects ▁are ▁referenced ▁by ▁similar ▁objects . ▁More ▁precisely , ▁objects ▁ ▁and ▁ ▁are ▁considered ▁to ▁be ▁similar ▁if ▁they ▁are ▁pointed ▁from ▁objects ▁ ▁and ▁, ▁respectively , ▁and ▁ ▁and ▁