THU_NGN at SemEval-2018 Task 2: Residual CNN-LSTM Network with Attention for English Emoji Prediction
Paper · 2018 · Chuhan Wu, Fangzhao Wu, Sixing Wu et al.
Summary
This paper describes the THU_NGN entry to SemEval-2018 Task 2, subtask 1. The task is to guess which of 20 emojis originally accompanied an English tweet after the emoji has been removed. The team built RCLA, a residual CNN-LSTM with attention, which processes the tweet in stages:
- Word embeddings, pre-trained on tweets and fine-tuned, are joined with POS tags from Ark-Tweet-NLP.
- A Bi-LSTM reads the tweet for long-range context.
- An attention layer reweights each hidden state.
- A three-layer CNN with residual links and several window sizes picks up local patterns, followed by max pooling.
- 45 lexicon-based sentiment features from the AffectiveTweets package are concatenated before a softmax classifier.
Because the emoji classes are heavily skewed, the cross-entropy loss gives rarer labels larger weights. The system scored 30.25% macro-F on the test set, placing 7th of 48 teams. An ablation shows that each component adds a modest gain. The work is useful as a careful, well-ablated recipe for noisy short-text classification with imbalanced labels.
Key points
- The data has 20 emoji classes, 489,277 training tweets, and 50,000 tweets each in the trial and test sets. Evaluation uses macro-averaged F-score. The top emoji covers over 20% of the data, while some classes have only about 2–3%.
- Embeddings come from Barbieri et al. (2016b): 300-dimensional vectors trained on 20 million geo-localized tweets.
- Hyperparameters were tuned on the trial set:
- Bi-LSTM hidden size 300
- CNN windows of 2/3/4 with 200 filters
- dropout 0.2 and batch size 500
- RMSProp optimizer, up to 100 epochs
- The architecture ablation gives these macro-F scores: LSTM 28.72, CNN 28.86, CL 29.35, RCL 29.61, RCLA 30.25.
- The feature ablation gives: no extra features 29.08, +POS 29.76, +Sentiment 29.55, both 30.25. The sentiment features come from the TweetToLexiconFeatureVector and TweetToSentiStrengthFeatureVector filters in Weka.
Interesting ideas
- I1. Class weights in the loss grow as a label's frequency shrinks, using a square-root scaling, so rare classes get more weight without letting them dominate training.
- I2. The attention weights rescale each position's hidden state rather than collapsing the sentence into one vector, so later layers still see word order while the per-token weights remain inspectable.
- I3. Hand-built lexicon features (sentiment scores, emoticon and hashtag cues) are concatenated with the learned representation just before the classifier, giving a transparent channel next to the neural one.
- I4. An incremental ablation ladder adds one component at a time (CNN or LSTM alone, then CL, then residual, then attention, then each feature group) and reports each step's macro-F, which makes the contribution of every part visible.
- I5. The error analysis separates two kinds of confusion: label pairs that share meaning (both used for happy tweets) and pairs that merely look alike.
For Mova
How these ideas could serve Mova, our small open language model — its files, stages and tests:
- I1 (learn): Mova could weight rare UD relations or uncommon VerbNet roles this way when training parsers on skewed silver data, instead of letting frequent labels swamp the gradient.
- I2 (frames): A per-token salience score that keeps word order could flag which words drive an irony or speech-act decision, while leaving the full sequence available for role assignment.
- I3 (frames): Lexicon-based polarity features could be fed into irony and implicature detection as named, inspectable inputs, which helps keep each decision explainable.
- I4 (learn): Mova's evaluation could adopt this stepwise ladder, paired with negative controls, to prove that each repair rule or witness parser actually earns its place.
- I5 (learn): Splitting parser or frame confusions into "semantically overlapping" and "near-duplicate inventory" cases could show where label sets should be merged, rather than modelled harder.
Institutions
Fields, topics and concepts
📚 Shelves 5The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksArts and Humanities · 16,039 worksLanguage and Linguistics · 15,891 worksHuman-Computer Interaction · 141 works
🧭 Topics 1Research subjects and languages the work is about.English · 2,263 works
Cite
Cite as Chuhan Wu, Fangzhao Wu, Sixing Wu, Zhigang Yuan, Junxin Liu and Yongfeng Huang. 2018. THU_NGN at SemEval-2018 Task 2: Residual CNN-LSTM Network with Attention for English Emoji Prediction. Proceedings of the 12th International Workshop on Semantic Evaluation.
@inproceedings{wu2018thu,
title = {{THU\_NGN at SemEval-2018 Task 2: Residual CNN-LSTM Network with Attention for English Emoji Prediction}},
author = {Chuhan Wu, Fangzhao Wu, Sixing Wu, Zhigang Yuan, Junxin Liu and Yongfeng Huang},
booktitle = {Proceedings of the 12th International Workshop on Semantic Evaluation},
year = {2018},
doi = {10.18653/v1/s18-1063},
url = {https://doi.org/10.18653/v1/s18-1063}
}References
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