This paper examines the differences in the robustness of syntactic dependency structures in written English produced by learners of varying proficiency levels and by native English speakers. The robustness of these dependency structures is represented by their degree centralities, and corpus-based investigation revealed that learners with higher proficiency levels tend to produce sentences with lower degree centralities. This means that they produce more robust, and more embedded sentences. It is also revealed that the sentences produced by native speakers of English tend to produce more embedded sentences than non-native speakers.

This paper describes the details of UD-based morphological and syntactic annotations on Esperanto texts to construct its small-scale UD treebank. Though it was created as an international auxiliary language, Esperanto has increasingly been studied as a natural language both in linguistics and in NLP. This paper introduces the detail of manual annotation of UD morphological and relational tags and describes how the frequencies of these tags differ across the treebanks and discusses the possibility of future research of Esperanto as a natural language.