Defining Verbal Synonyms: between Syntax and Semantics

While studying verbal synonymy, we have investigated the relation between syntax and semantics in hope that the exploration of this relationship will help us to get more insight into the question of synonymy as the relationship relating (similar) meanings between different lexemes. Most synonym lexicons (Wordnets and similar thesauri) are based on an intuition about the similarity of word meanings, or on notions like “semantic roles.” In some cases, syntax is also taken into account, but we have found no annotation and/or evaluation experiment to see how strongly can syntax contribute to synonym specification. We have prepared an annotation experiment for which we have used two treebanks (Czech and English) from the Universal Dependencies (UD) set of parallel corpora (PUDs) in order to see how strong correlation exists between syntax and the assignment of verbs in context to pre-determined (bilingual) classes of synonyms. The resulting statistics confirmed that while syntax does support decisions about synonymy, such support is not strong enough and that more semantic criteria are indeed necessary. The results of the annotation will also help to further improve rules and specifications for creating synonymous classes. Moreover, we have collected evidence that the annotation setup that we have used can identify synonym classes to be merged, and the resulting data (which we plan to publish openly) can possibly serve for the evaluation of automatic methods used in this area.