A Wordnet from the Ground Up

106 Chapter 4. Extracting Relation Instancesand(in(cas[0],nom),llook(-1,begin,$T,equal(base[$T],{"taki"})),equal(base[$+1T],{"jak"}),only($+2T,-1,$AR,or(inter(flex[$AR],{adjective , adjectival participles , adverb ,adverbial participles , noun ,numeral }),in(orth[$AR],{"i","lub","czy","oraz","a",",",":","(",")"}))),llook($-1T,begin,$N,and(inter(flex[$N],{noun }),equal(base[$N],{"base form of NLU2"}),in(cas[$N],{nom,acc,dat,inst,loc,voc}))),only($+1N,$-1T,$AL,or(inter(flex[$AL],{adjective , adjectival participles , adverb ,adverbial participles , numeral }),and(inter(flex[$AL],{noun , pronouns }),equal(cas[$AL],{gen})))))Figure 4.2: The essentials of the TakichJak pattern implementation in JOSKIPIDuring the evaluation, an extracted LU pair could be classified as a correct instanceof hypernymy (possibly indirect, with longer paths accepted), or as one of two formsof nearly correct instances:• not the expected hyponym/hypernym order; such pairs occurred more oftenamong the results of the NomToNom pattern in which the direction is not markedby grammatical case;• small inaccuracies in one of the LUs: it is part of a larger multiword LU, or ithas a wrong number value, or it is represented by a wrong root (a tagger error).All other pairs were classified as incorrect. The results in Table 4.1 have been calculatedwith the assumption that correct and nearly correct instances are positive. If weexcluded the nearly correct class, the results would be about 20% lower. The resultswould be very low if we only sought direct hypernymy. This clearly suggests that theextracted pairs are not directly helpful in expanding the core plWordNet, but they stillare a valuable source of knowledge. They show not only semantic similarity of theLUs in a pair, but also the direction of the relation. Indirect hypernyms can be helpful