A Wordnet from the Ground Up

48 Chapter 3. Discovering Semantic Relatednessan authority. Without venturing into a discussion of the merits of such a stance, weadopt the tenet of trustworthiness. Thus, automated methods of extracting elements ofa wordnet should at least deliver some form of intelligent browsing. This should drawthe linguist’s attention to selected LUs that could be linked to a given LU by a wordnetrelation. Henceforth, we will mean wordnet relations as all lexico-semantic relationsdefined in wordnets, including PWN, EWN and plWordNet, with the emphasis on thelatter.Software tools in support of wordnet construction can be divided into four mainclasses, those which• offer better corpus-browsing capability,• criticize existing wordnet content,• suggest possible expansion to existing wordnet content,• suggest possible substructures of relations over LUs.Corpus-browsing tools rely on the statistical analysis of a large corpus in search fordistributional associations of LUs — this is discussed in Section 3.4 — or pattern-basedextraction of relation instances — Section 4.Tools that criticize an existing wordnet, termed wordnet critics here, can producelists of relation instances missing in the wordnet, or mark already included relationinstances as dubious. Wordnet critics can be based on the full range of methods:pattern-based, e.g. (Hearst, 1998), measures of semantic relatedness and hybrid combinationsof the two; this is discussed in Section 4.5.An automatic tool might suggest simple expansion of a wordnet, such as addingrelation instances whose one element is already present in the wordnet. A moreadvanced suggestion might be the merging of a part of the wordnet with a subgraph ofLUs linked by wordnet relations – in effect, a “sub-wordnet” – which has been extractedautomatically and is connected to this part by at least a few relation instances. Thesimpler forms of expansion can be based on any combination of methods. To extractsynsets automatically and link them to a wordnet by some relation is inconceivablewithout clustering LUs; we discussed this in Section 3.5.3.2 Basic Division: Patterns versus Statistical MassMethods of the acquisition of lexico-semantic relations belong to two main categoriesthat represent two paradigms of different origins; see (Matsumoto, 2003, Panteland Pennacchiotti, 2006):