▁to ▁tag ▁sens es ▁is ▁far ▁more ▁difficult . ▁While ▁users ▁can ▁memor ize ▁all ▁of ▁the ▁possible ▁parts ▁of ▁speech ▁a ▁word ▁can ▁take , ▁it ▁is ▁often ▁impossible ▁for ▁individuals ▁to ▁memor ize ▁all ▁of ▁the ▁sens es ▁a ▁word ▁can ▁take . ▁Moreover , ▁humans ▁do ▁not ▁agree ▁on ▁the ▁task ▁at ▁hand ▁– ▁give ▁a ▁list ▁of ▁sens es ▁and ▁sentences , ▁and ▁humans ▁will ▁not ▁always ▁agree ▁on ▁which ▁word ▁belongs ▁in ▁which ▁sense . ▁ ▁As ▁human ▁performance ▁serves ▁as ▁the ▁standard , ▁it ▁is ▁an ▁upper ▁bound ▁for ▁computer ▁performance . ▁Human ▁performance , ▁however , ▁is ▁much ▁better ▁on ▁co arse - gra ined ▁than ▁fine - gra ined ▁dist in ctions , ▁so ▁this ▁again ▁is ▁why ▁research ▁on ▁co arse - gra ined ▁dist in ctions ▁has ▁been ▁put ▁to ▁test ▁in ▁recent ▁W SD ▁evaluation ▁exer cis es . ▁ ▁Prag mat ics ▁Some ▁A I ▁research ers ▁like ▁Douglas ▁Len at ▁argue ▁that ▁one ▁cannot ▁parse ▁mean ings ▁from ▁words ▁without ▁some ▁form ▁of ▁common ▁sense ▁ont ology . ▁This ▁lingu istic ▁issue ▁is ▁called ▁p rag mat ics . ▁For ▁example , ▁comparing ▁these ▁two ▁sentences : ▁ ▁" J ill ▁and ▁Mary ▁are ▁moth ers ." ▁– ▁( each ▁is ▁independently ▁a ▁mother ). ▁ ▁" J ill ▁and ▁Mary ▁are ▁sister s ." ▁– ▁( they ▁are ▁sister s ▁of ▁each ▁other ). ▁To ▁properly ▁identify ▁sens es ▁of ▁words ▁one ▁must ▁know ▁common ▁sense ▁facts . ▁Moreover