Adapting Semantic Role Labeling to New Genres and Languages

Myers, Skatje Katharina

Graduate Thesis Or Dissertation

Adapting Semantic Role Labeling to New Genres and Languages Public Deposited

Analytics

Download PDF

Citations

Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/js956h393

Abstract

Semantic role labeling (SRL) is the identification of semantic predicates and their participants within a sentence, which is vital for deeper natural language understanding. State-of-the-art SRL models require annotated text for training, but those annotations don't exist for many languages and domains. The ability to annotate new corpora is hampered by limited time and budget. We explore two different ways of reducing the annotation required to produce SRL systems for new domains or languages: active learning and annotation projection.

Active learning reduces annotation requirements by selecting just the most informative training instances through an iterative process of training and annotation. In this work, we investigate the use of Bayesian Active Learning by Disagreement, ways of tuning it for SRL, and assessing its performance across multiple corpora. We study the choices being made by different selection methods over the course of iterations, examining vocabulary coverage, diversity, predicates selected, and the shifts in confidence. We also explore the impact of various strategies of selecting the initial training data. We investigate a number of potentially influential factors within batches of queries, such as diversity and disagreement scores. In order to reduce the overhead of training time, we additionally compare the effect of increasing the amount of queries being selected on each iteration.

Abstract Meaning Representations (AMRs) are increasingly popular semantic representations of whole sentences. Based on our successful results using active learning to assess the informativeness of annotation instances for SRL, we look into whether the commonalities between these representations can be leveraged to supply targeted annotation for AMR parsing.

Finally, we explore annotation projection of SRL. This approach attempts to create semantic annotations in a target language given parallel translations that have been given SRL annotations through manual or automatic means. We assess the recently developed Russian PropBank and the feasibility of generating the same semantic annotations by projecting from the English PropBank annotation. We use both our own system with English-Russian automatic word alignments and the recent Universal PropBanks 2.0. We examine the types of errors that arise from inconsistencies or gaps in annotations as well as systemic issues arising from the strong English-bias of the projections. This analysis leads us to the development of several filtering techniques that improve the precision of the projections.

Creator