A Wordnet from the Ground Up

70 Chapter 3. Discovering Semantic Relatednessrecognise properly. We have, however, significantly limited the range of constructionswhere this constraint is met, so the achieved accuracy is relatively good – see Table 3.6.Moreover, in testing the presence of adjectival words between the target LU and thelexical element, we refer to agreement for more accurate recognition. Modificationby a nominal lemma in genitive clearly refers to the lexical meaning of the modifiednominal. NmgC had a positive influence on the accuracy in the experiments – see(Piasecki et al., 2007b, Piasecki and Radziszewski, 2009).Verbal LUs are described in plWordNet not in terms of subcategorisation frames,but by the semantic and lexical relations. So instead of recognising syntactic frames 14 ,we applied morphosyntactic constraints in a way similar to the description of nominalLUs. The description of occurrences of verbal LUs comprises four templates ofmorphosyntactic constraints (the lexical elements have been italicised):NSb – a particular noun as a potential subject of the given verb,NArg – a noun in a particular case as a potential verb argument,VPart – a present or past participle of the given verb as a modifier of some nominalLU 15 ,VAdv – an adverb in close proximity to the given verb.NSb is a symmetrical to the VsbC constraint applied to nominal LUs. Now nominalLUs are the lexical elements searched for. The NArg template is parametrised bytwo values: a case value (the nominative value is excluded as covered by NSb) anda nominal lexical element. Because there is no agreement between a verb and itsargument and we had no description of verb subcategorisation frames for Polish, theNArg implementation is very straightforward. Having the verb in the centre (position0) we are looking for the first occurrence of the given lexical element in the given caseunless it is separated by an occurrence of another verb (when we cannot disambiguatethe attachment). VPart explores the common use of present and past participles asadjectival modifiers of nominal LUs. Verbs are described via their occurrences asparticiples and lexical elements are the modified nominal LUs. The constraint is verysimilar to the AdjC constraint for nominal LUs. For the VAdv constraint we test thepresence of an lexical elements – an adverb – at the two closest positions to the leftor right. Adverbs have no grammatical categories except degree, so only distance canbe considered.MSRs for adjectives were constructed as a by-product of larger projects in (Hatzivassiloglouand McKeown, 1993, Freitag et al., 2005). Extraction of distributional14 This might be very difficult due to the lack of a shallow parser.15 A subtle agreement test and additional structural conditions distinguish such pairs from verbcomplementpairs.