Headed-Span-Based Projective Dependency Parsing
We propose a new paradigm for projective dependency parsing based on headed spans. In a projective dependency tree, the subtree rooted at each word covers a contiguous sequence (i.e., a span) in the surface order. We call a span marked with a root word headed span. A projective dependency tree can be represented as a collection of headed spans. We decompose the score of a dependency tree into the scores of the headed spans and design a novel $O(n^3)$ dynamic programming algorithm to enable global training and exact inference. The advantages of our headed-span-based dependency parsing include that it captures subtree information more adequately than first-order graph-based methods and performs global optimization in decoding (in contrast to transition-based methods). We evaluate our method on PTB, CTB, and UD and it achieves competitive results in comparison with previous methods.
Code (0)
등록된 구현이 없습니다.
Tasks
Dependency Parsingglobal-optimizationSimilar Papers 제목 키워드 기반
Headed-Span-Based Projective Dependency Parsing
We propose a new method for projective dependency parsing based on headed spans. In a projective dependency tree, the largest subtree rooted at each word covers a contiguous sequence (i.e., a span) in the surface order. …
Constituency ParsingDependency ParsingCombining (Second-Order) Graph-Based and Headed-Span-Based Projective Dependency Parsing
Graph-based methods are popular in dependency parsing for decades, which decompose the score of a dependency tree into scores of dependency arcs. Recently, (Yang and Tu, 2021) propose a headed-span-based method that deco…
ARCDependency ParsingCombining (second-order) graph-based and headed-span-based projective dependency parsing
Graph-based methods, which decompose the score of a dependency tree into scores of dependency arcs, are popular in dependency parsing for decades. Recently, \citet{Yang2022Span} propose a headed-span-based method that de…
ARCDependency ParsingA tree interpretation of arc standard dependency derivation
Arc-standard derivations over projective dependency trees can be interpreted as the incremental construction of lexicalized ordered trees with contiguous yields. Each \textsc{shift}, \textsc{leftarc}, and \textsc{rightar…
Efficient Discontinuous Phrase-Structure Parsing via the Generalized Maximum Spanning Arborescence
We present a new method for the joint task of tagging and non-projective dependency parsing. We demonstrate its usefulness with an application to discontinuous phrase-structure parsing where decoding lexicalized spines a…
Dependency Parsing