Dependency Head Annotation for Myanmar Dependency Treebank

Abstract

Complete manual annotation of dependency treebank needs resources like annotators and annotation tools and takes long time and has high possibility of inconsistent annotations for free word order languages such as Myanmar. This paper describes a dependency head annotation scheme with Universal part-of-speech and Universal Dependencies for Myanmar dependency treebank. Currently 22,810 sentences and 680,218 tokens were annotated from three corpora for Myanmar dependency treebank. Some language specific issues are also described with examples. Raw syntactic structures were annotated automatically by UDPipe according to the Universal Dependencies based on Universalpart-of-speech tag scheme. Then unsupervised annotated dependency head structures have been manually updated in post processing. To be reliable and speedy post process with reduced errors for manual updating, selected sentences were added to the training data after being updated. After that the model has been retrained and the remaining sentences were parsed by UDPipe. Post processing was repeated until all sentences were updated. Some specifications of dependency annotation schemes in sentences encountered in post processing are presented with examples. For parsing performance of annotated data, cross validation tests and parsing experiments were performed. Moreover, annotated treebank data have also been evaluated by CoNLL 2017 evaluation script for parsing performance. Results of parsing experiments and evaluation are also reported by unlabeled and labeled attachment scores and demonstrated that the proposed method is a suitable way for building Myanmar dependency trees. Moreover, syntax structures of treebank are also analyzed and syntax information is also presented. This dependency head annotation for dependency treebank is the first work for Myanmar language as far as we know.