Resources for Turkish Dependency Parsing: Introducing the BOUN Treebank and the BoAT Annotation Tool

In this paper, we describe our contributions and efforts to develop Turkish resources, which include a new treebank (BOUN Treebank) with novel sentences, along with the guidelines we adopted and a new annotation tool we developed (BoAT). The manual annotation process we employed was shaped and implemented by a team of four linguists and five NLP specialists. Decisions regarding the annotation of the BOUN Treebank were made in line with the Universal Dependencies framework, which originated from the works of De Marneffe et al. (2014) and Nivre et al. (2016). We took into account the recent unifying efforts based on the re-annotation of other Turkish treebanks in the UD framework (T\"urk et al., 2019). Through the BOUN Treebank, we introduced a total of 9,757 sentences from various topics including biographical texts, national newspapers, instructional texts, popular culture articles, and essays. In addition, we report the parsing results of a graph-based dependency parser obtained over each text type, the total of the BOUN Treebank, and all Turkish treebanks that we either re-annotated or introduced. We show that a state-of-the-art dependency parser has improved scores for identifying the proper head and the syntactic relationships between the heads and the dependents. In light of these results, we have observed that the unification of the Turkish annotation scheme and introducing a more comprehensive treebank improves performance with regards to dependency parsing