Repository logo
 

Structured Learning with Inexact Search: Advances in Shift-Reduce CCG Parsing


Loading...
Thumbnail Image

Type

Thesis

Change log

Authors

Xu, Wenduan 

Abstract

Statistical shift-reduce parsing involves the interplay of representation learning, structured learning, and inexact search. This dissertation considers approaches that tightly integrate these three elements and explores three novel models for shift-reduce CCG parsing. First, I develop a dependency model, in which the selection of shift-reduce action sequences producing a dependency structure is treated as a hidden variable; the key components of the model are a dependency oracle and a learning algorithm that integrates the dependency oracle, the structured perceptron, and beam search. Second, I present expected F-measure training and show how to derive a globally normalized RNN model, in which beam search is naturally incorporated and used in conjunction with the objective to learn shift-reduce action sequences optimized for the final evaluation metric. Finally, I describe an LSTM model that is able to construct parser state representations incrementally by following the shift-reduce syntactic derivation process; I show expected F-measure training, which is agnostic to the underlying neural network, can be applied in this setting to obtain globally normalized greedy and beam-search LSTM shift-reduce parsers.

Description

Date

2017-08

Advisors

Clark, Stephen

Keywords

Structured Prediction, Structured Learning with Inexact Search, Violation-Fixing Structured Perceptron, Recurrent Neural Networks, LSTMs, Combinatory Categorial Grammar, Shift-Reduce Transition-based Parsing

Qualification

Doctor of Philosophy (PhD)

Awarding Institution

University of Cambridge
Sponsorship
The Carnegie Trust for the Universities of Scotland; The Cambridge Trust