A Dependency Parser for Tweets
What it is about
Tweets break the assumptions of newswire parsers: many tokens (retweet markers, usernames, hashtags, URLs, punctuation) have no syntactic role, a tweet can hold several utterances with their own roots, and multiword names and idioms are common. The authors annotate 929 POS-tagged tweets (Tweebank, about 12,000 tokens) directly as dependencies, with a graph-fragment notation that lets annotators leave tokens unselected, group multiword expressions, and mark several roots. Their parser, TweeboParser, is a second-order TurboParser adapted to skip unselected tokens (they stay as features), to allow several roots on a wall symbol, and to use a Penn Treebank parser's arc scores as a stacking feature, with Brown clusters from tweets. On the new test set of 201 tweets the parser reaches 80.9 unlabeled F1, against 76.1 on an older Penn-style test set, and its ablations show that the parsing adaptations are worth 1.7 points and the Penn Treebank feature 0.7 points on the new test set (3.5 points on the Penn-style set).
Ideas
- I1.
en/src/parse.rsunselected tokens: exclude punctuation and other non-syntactic tokens from the arcs but keep them as features of neighbouring arcs, as the paper's decoder does; measure UAS and LAS on EWT test with and without punctuation arcs (the paper's Table 3 shows about 2 points on tweets, our number will differ). - I2. Wall-symbol multi-root for utterance-level data: allow several roots in the
enparser for CHILDES and chat lines, behind a dialect flag, while the registry gate still rejects them in edited text; measure the number of multi-root sentences rejected per 1k lines of CHILDES with the gate on and off. - I3.
en/src/morph.rsanden/seeds/lexicon: group multiword names and idioms as one unit, parse the unit internally, and reattach the arcs to its head, as the paper does; measure head attachment on EWT test sentences that contain such units. - I4. Robustness check on Tweebank (test only, the data is non-commercial): UAS of the
enparser trained on EWT and ESLspok, against the paper's 80.9 on its new test set; use it as a domain-shift number, not as a target.
For Mova
Touches languages/en/38-dialogue-and-discourse-markers, 19-lexicon-mwe-register and 37-register-and-variation, and the en crate (parse.rs, morph.rs, ctx.rs), tools/treeagree and the multi-root rule of the mova dialect. Tweebank is non-commercial: test only. Measure first the effect of excluding punctuation arcs on EWT test, which costs little and tests the idea behind I1.
Library summary
Written for the Research library (claude-opus-5-5) from the paper text, in our own words: the license "CC BY-NC-SA 3.0 (ACL Anthology, before 2016)" does not allow redistributing the text itself. Original — aclanthology.org/D14-1108.pdf
Summary
Off-the-shelf parsers trained on the Penn Treebank do poorly on tweets, and no syntactic parser built specifically for Twitter existed. The authors present TWEEBOPARSER, a dependency parser for English tweets, together with TWEEBANK, a new dependency corpus. They argue that Penn Treebank conventions fit edited news but not informal posts, so they designed annotation rules around tweet-specific problems:
- tokens with no syntactic role (retweet markers, URLs, many hashtags, punctuation)
- multiword expressions treated as single units
- tweets that contain several independent utterances
- richer structure inside noun phrases
Most of the annotation was done in a single day by about two dozen lightly trained annotators. On the modelling side, they adapted the graph-based TurboParser to handle unselected tokens and multiple roots. They also brought in Penn Treebank knowledge cheaply through stacking-style features rather than training directly on it. The parser exceeds 80% unlabeled attachment on the new test set. This shows that a small, fast, domain-aware annotation effort can beat a much larger out-of-domain treebank.
Key points
- TWEEBANK corpus: 929 tweets (12,318 tokens) taken from the POS-tagged corpus of Owoputi et al. (2013), split roughly evenly between OCT27 and DAILY547. It was annotated with GFL-style graph fragments.
- Token selection:
- Annotators kept 75.6% of tokens as syntactically active.
- A rule-based filter reproduces these choices with about 95% accuracy.
- A first-order sequence model trained with the structured perceptron reaches 97.4%.
- Main results: The parser scores 80.9% unlabeled attachment F1 on TEST-NEW and 76.1% on TEST-FOSTER. With gold POS tags and gold token selection, TEST-NEW rises to 83.2%.
- Comparison with Penn Treebank training: A second-order TurboParser trained on 39,832 Penn Treebank sentences scores about 7.8 points lower on TEST-NEW. The tweet parser uses only 1,473 Twitter utterances.
- Ablations:
- The parsing adaptations add roughly 2–3 points.
- Penn Treebank-derived features help on both test sets, especially TEST-FOSTER.
- Brown cluster features did not give consistent gains with this small training set.
Interesting ideas
- Explicit token selection: Annotators mark which tokens carry syntax, and the parser skips the rest instead of forcing arbitrary attachments. This saves annotation effort in any noisy genre (chats, forums, OCR output) where many tokens are decoration or metadata.
- Reversible handling of multiword expressions: Annotators mark MWEs as flat units. An existing parser then fills in their internal structure, using a special arc label so the step can be undone. This keeps annotation simple while still letting you train a standard tree-based parser.
- Multiple roots instead of sentence segmentation: Several utterances may attach to the root ("wall") symbol, so segmentation falls out of the parse itself. This is useful wherever sentence boundaries are unreliable, such as transcripts or messages.
- Using a big out-of-domain treebank through features: Penn Treebank parser output is fed in as stacking-style features rather than as direct training data. The model can then rely on that outside knowledge only as much as it proves helpful, which is a cheap route for low-resource domains or languages.
- Time-spread data sampling: Mixing tweets from one day with one random tweet per day over many months reduces overfitting to topics specific to a single event. This is worth copying when building any social-media dataset.
Cite
@inproceedings{kong2014dependency,
title = {{A Dependency Parser for Tweets}},
author = {Kong, Lingpeng and Schneider, Nathan and Swayamdipta, Swabha and Bhatia, Archna and Dyer, Chris and Smith, Noah A.},
booktitle = {Proceedings of the 2014 Conference on Empirical Methods in Natural Language Processing (EMNLP)},
year = {2014},
doi = {10.3115/v1/d14-1108},
url = {https://doi.org/10.3115/v1/d14-1108}
}References
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