4 and 7-bit Labeling for Projective and Non-Projective Dependency Trees
We introduce an encoding for parsing as sequence labeling that can represent any projective dependency tree as a sequence of 4-bit labels, one per word. The bits in each word's label represent (1) whether it is a right or left dependent, (2) whether it is the outermost (left/right) dependent of its parent, (3) whether it has any left children and (4) whether it has any right children. We show that this provides an injective mapping from trees to labels that can be encoded and decoded in linear time. We then define a 7-bit extension that represents an extra plane of arcs, extending the coverage to almost full non-projectivity (over 99.9% empirical arc coverage). Results on a set of diverse treebanks show that our 7-bit encoding obtains substantial accuracy gains over the previously best-performing sequence labeling encodings.
Code (0)
등록된 구현이 없습니다.
Tasks
ARCMethods 이 논문이 사용한 방법론
Similar Papers 제목 키워드 기반
Exploiting Dynamic Oracles to Train Projective Dependency Parsers on Non-Projective Trees
Because the most common transition systems are projective, training a transition-based dependency parser often implies to either ignore or rewrite the non-projective training examples, which has an adverse impact on accu…
Dependency 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…
Hierarchical Bracketing Encodings for Dependency Parsing as Tagging
We present a family of encodings for sequence labeling dependency parsing, based on the concept of hierarchical bracketing. We prove that the existing 4-bit projective encoding belongs to this family, but it is suboptima…
Dependency ParsingEfficient Parsing for Head-Split Dependency Trees
Head splitting techniques have been successfully exploited to improve the asymptotic runtime of parsing algorithms for projective dependency trees, under the arc-factored model. In this article we extend these techniques…
ARCDependency ParsingBracketing Encodings for 2-Planar Dependency Parsing
We present a bracketing-based encoding that can be used to represent any 2-planar dependency tree over a sentence of length n as a sequence of n labels, hence providing almost total coverage of crossing arcs in sequence …
Dependency ParsingPOSSentence