Valency Lexicon of Czech Verbs: Towards Formal Description of Valency and Its Modeling in an Electronic Language Resource

Valency refers to the capacity of verb (or a word belonging to another part of speech) to take a specific number and type of syntactically dependent language units. Valency information is thus related to particular lexemes and as such it is necessary to describe valency characteristics for separate lexemes in the form of lexicon entries. A valency lexicon is indispensable for any complex Natural Language Processing application based on the explicit description of language phenomena. At the same time such lexicons are necessary for building language resources which provide the basis for tools using machine learning techniques. The present habilitation work consists of a collection of already published scientific papers. It summarizes the results of building a lexical database of Czech verbs. It concentrates on three essential topics. The first of them is the formal representation of valency properties of Czech verbs in the valency lexicon. The logical organization of richly structured lexicon data is presented here. The second topic concerns new theoretical issues that result from the extensive processing of language material, namely the concept of quasi-valency complementation and adequate processing of verb alternations. The third topic addresses questions of formal modeling of a natural language. A new formal model of dependency syntax based on a novel concept of restarting automata is introduced here. The main applied product of the work presented here is the publicly available Valency Lexicon of Czech Verbs VALLEX, a large-scale, high-quality lexicon which contains semantic and valency characteristics for the most frequent Czech verbs. VALLEX has been designed with emphasis on both human and machine-readability. Therefore, both linguists and developers of applications within the Natural Language Processing domain can use it.