Cross-Lingual Dependency Parsing with Unlabeled Auxiliary Languages
Wasi Uddin Ahmad, Zhisong Zhang, Xuezhe Ma, Kai-Wei Chang, Nanyun Peng · 2019
Cross-lingual transfer learning has become an important weapon to battle the unavailability of annotated resources for low-resource languages.One of the fundamental techniques to transfer across languages is learning language-agnostic representations, in the form of word embeddings or contextual encodings.In this work, we propose to leverage unannotated sentences from auxiliary languages to help learning language-agnostic representations.Specifically, we explore adversarial training for learning contextual encoders that produce invariant representations across languages to facilitate cross-lingual transfer.We conduct experiments on cross-lingual dependency parsing where we train a dependency parser on a source language and transfer it to a wide range of target languages.Experiments on 28 target languages demonstrate that adversarial training significantly improves the overall transfer performances under several different settings.We conduct a careful analysis to evaluate the language-agnostic representations resulted from adversarial training.