A Transition-Based Directed Acyclic Graph Parser for UCCA

ACL 2017  ·  Daniel Hershcovich, Omri Abend, Ari Rappoport ·

We present the first parser for UCCA, a cross-linguistically applicable framework for semantic representation, which builds on extensive typological work and supports rapid annotation. UCCA poses a challenge for existing parsing techniques, as it exhibits reentrancy (resulting in DAG structures), discontinuous structures and non-terminal nodes corresponding to complex semantic units. To our knowledge, the conjunction of these formal properties is not supported by any existing parser. Our transition-based parser, which uses a novel transition set and features based on bidirectional LSTMs, has value not just for UCCA parsing: its ability to handle more general graph structures can inform the development of parsers for other semantic DAG structures, and in languages that frequently use discontinuous structures.

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Task Dataset Model Metric Name Metric Value Global Rank Result Benchmark
UCCA Parsing SemEval 2019 Task 1 Transition-based English-Wiki (open) F1 72.8 # 4
English-20K (open) F1 67.2 # 3


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