A Wordnet from the Ground Up

1.3. Early Decisions 19Merge Model: the selection is done in a local resource and the synsetsand their language-internal relations are first developed separately, afterwhich the equivalence relations to WordNet 1.5 are generated.Expand Model: the selection is done in WordNet 1.5 and the Word-Net 1.5 synsets are translated (using bilingual dictionaries) into equivalentsynsets in the other language. The wordnet relations are taken overand where necessary adapted to EuroWordNet. Possibly, monolingual resourcesare used to verify the wordnet relations imposed on non-Englishsynsets.It has been observed that the expand model can lead to a wordnet biased byWordNet 1.5. For many languages, however, either no electronic monolingual resources– extended monolingual dictionaries or thesauri – are available, or existing resourcesare small, often with limited information in their entries. There have been suggestionsthat for such languages the expand model can work well in wordnet development.In the scope of EWN, the expand model was adopted for the Spanish and Frenchwordnets. Later several other wordnet development projects also adopted it, includingthe Croatian WordNet (Raffaelli et al., 2008) and Hungarian WordNet (Miháltz et al.,2008).A wordnet constructed following the merge model should provide a description oflexico-semantic relations closer to the spirit of the given language, in that it is lessinfluenced by the design decisions in a wordnet for another language (probably English),often of a significantly different type. The merge model, however, requires richresources at the outset, for example, a monolingual dictionary with senses identified,detailed definitions, thematic codes for senses and some semantic structuring. Suchresources are created for humans readers, so to construct a wordnet from them is morethan merely a matter of copying 10 – see (Pedersen and Nimb, 2008) for the use ofresources in the DanNet project. The difference is also clear when one compares PWNand LDCE (Bullon et al., 2003), or plWordNet and (Dubisz, 2004).1.3.2 Why we chose the merge approachNo electronic dictionary on which we could base the construction of Polish wordnetwas available 11 . In addition, we did not want to consider indiscriminate mapping ofPWN, and we dismissed the idea of translating it into Polish. In effect, we decidedto build plWordNet from scratch. On the other hand, we wanted to keep plWordNet10 If a dictionary contains rich information structured in a way that facilitates NLP, we face anotherquestion: is the wordnet the best way of describing lexical semantics for NLP? We have no experience toanswer such a question, because the Polish language, unfortunately, is not blessed with such abundance.11 The existing Polish electronic dictionaries, for example (Dubisz, 2004) or (PWN, 2007), are notfreely available for research, and in any event their structure makes their usefulness limited.