Transition-Based Coding and Formal Language Theory for Ordered Digraphs

Anssi Yli-Jyrä


Abstract
Transition-based parsing of natural language uses transition systems to build directed annotation graphs (digraphs) for sentences. In this paper, we define, for an arbitrary ordered digraph, a unique decomposition and a corresponding linear encoding that are associated bijectively with each other via a new transition system. These results give us an efficient and succinct representation for digraphs and sets of digraphs. Based on the system and our analysis of its syntactic properties, we give structural bounds under which the set of encoded digraphs is restricted and becomes a context-free or a regular string language. The context-free restriction is essentially a superset of the encodings used previously to characterize properties of noncrossing digraphs and to solve maximal subgraphs problems. The regular restriction with a tight bound is shown to capture the Universal Dependencies v2.4 treebanks in linguistics.
Anthology ID:
W19-3115
Volume:
Proceedings of the 14th International Conference on Finite-State Methods and Natural Language Processing
Month:
September
Year:
2019
Address:
Dresden, Germany
Editors:
Heiko Vogler, Andreas Maletti
Venue:
FSMNLP
SIG:
SIGFSM
Publisher:
Association for Computational Linguistics
Note:
Pages:
118–131
Language:
URL:
https://aclanthology.org/W19-3115
DOI:
10.18653/v1/W19-3115
Bibkey:
Cite (ACL):
Anssi Yli-Jyrä. 2019. Transition-Based Coding and Formal Language Theory for Ordered Digraphs. In Proceedings of the 14th International Conference on Finite-State Methods and Natural Language Processing, pages 118–131, Dresden, Germany. Association for Computational Linguistics.
Cite (Informal):
Transition-Based Coding and Formal Language Theory for Ordered Digraphs (Yli-Jyrä, FSMNLP 2019)
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PDF:
https://aclanthology.org/W19-3115.pdf