Unlexicalized Transition-based Discontinuous Constituency Parsing

02/24/2019
by   Maximin Coavoux, et al.
0

Lexicalized parsing models are based on the assumptions that (i) constituents are organized around a lexical head (ii) bilexical statistics are crucial to solve ambiguities. In this paper, we introduce an unlexicalized transition-based parser for discontinuous constituency structures, based on a structure-label transition system and a bi-LSTM scoring system. We compare it to lexicalized parsing models in order to address the question of lexicalization in the context of discontinuous constituency parsing. Our experiments show that unlexicalized models systematically achieve higher results than lexicalized models, and provide additional empirical evidence that lexicalization is not necessary to achieve strong parsing results. Our best unlexicalized model sets a new state of the art on English and German discontinuous constituency treebanks. We further provide a per-phenomenon analysis of its errors on discontinuous constituents.

READ FULL TEXT

page 1

page 2

page 3

page 4

research
10/20/2020

Supertagging-based Parsing with Linear Context-free Rewriting Systems

We present the first supertagging-based parser for LCFRS. It utilizes ne...
research
04/01/2019

Discontinuous Constituency Parsing with a Stack-Free Transition System and a Dynamic Oracle

We introduce a novel transition system for discontinuous constituency pa...
research
03/30/2020

Span-based discontinuous constituency parsing: a family of exact chart-based algorithms with time complexities from O(n^6) down to O(n^3)

We introduce a novel chart-based algorithm for span-based parsing of dis...
research
04/03/2017

A Transition-Based Directed Acyclic Graph Parser for UCCA

We present the first parser for UCCA, a cross-linguistically applicable ...
research
10/01/2020

Discontinuous Constituent Parsing as Sequence Labeling

This paper reduces discontinuous parsing to sequence labeling. It first ...
research
05/23/2018

A Transition-based Algorithm for Unrestricted AMR Parsing

Non-projective parsing can be useful to handle cycles and reentrancy in ...
research
03/11/2019

HLT@SUDA at SemEval 2019 Task 1: UCCA Graph Parsing as Constituent Tree Parsing

This paper describes a simple UCCA semantic graph parsing approach. The ...

Please sign up or login with your details

Forgot password? Click here to reset