ALT at SemEval-2020 Task 12: Arabic and English Offensive Language Identification in Social Media
Paper · 2020 · Sabit Hassan, Younes Samih, Hamdy Mubarak et al.
Summary
The paper reports the ALT team's entry for sub-task A of SemEval-2020 Task 12, which asks whether a tweet is offensive (OFF) or not (NOT). The team worked on Arabic and English. For Arabic, the 8,000 labelled training tweets were normalised and used with several classifiers, tuned by 5-fold cross-validation: fastText, multilingual BERT, a character-CNN plus BiLSTM network using Mazajak embeddings, and tf-idf n-gram SVMs. An SVM was further patched with a lexical list derived from valence scores. The final Arabic system takes a majority vote over three very different models and placed second of 53 teams, only 0.01 F1 below the winner. The English training data consisted of about 9M tweets labelled only with averaged machine confidence scores. The team turned these scores into silver labels by thresholding, added Wikipedia Detox, and fine-tuned multilingual BERT, which placed 18th of 82. A manual analysis of errors highlights two recurring problems: sarcasm and humour, and noisy gold labels.
Key points
- Arabic: majority vote of SVM & ValenceList, C-LSTM and Mult-BERT reached macro-F1 90.16% on the 2,000-tweet test set (2nd/53; top was 90.17%). The best single model in cross-validation was SVM + ValenceList at 88.9%.
- Mult-BERT alone was weak on Arabic tweets (82.9% in CV). The authors attribute this to the gap between its Wikipedia pretraining text and informal Twitter language.
- ValenceList contains the 160 most frequent words with valence score 1 toward OFF. Any tweet the SVM marked NOT but containing one of these words was relabelled OFF.
- English: training tweets came with a mean confidence and a standard deviation from several models instead of gold labels. Low-agreement items were dropped, and OLID 2019 served as the dev set. Mult-BERT trained on these labels plus Wikipedia Detox scored 89% on OLID 2019 and 91.14% on the 3,887-tweet test set (18th/82; top 92.04%).
- In 100 sampled errors per language, humour/sarcasm caused 15% (Arabic) and 22% (English) of false positives, and 29% (Arabic) and 9% (English) of false negatives. Label noise accounted for roughly 13–29% across error types.
Interesting ideas
- I1. Turn soft scores from many models into training labels by keeping only items where the mean is clearly on one side and the spread between models is small, so confusing cases never enter training.
- I2. Place a tiny, inspectable lexical override after a statistical classifier: a short list of words that strongly signal one class flips only the predictions it can confidently correct.
- I3. Build the ensemble from models that differ in kind (n-gram SVM, character/word neural net, pretrained transformer) and combine them by plain majority vote to cancel each model's typical mistakes.
- I4. Hand-label a random sample of about 100 errors into a small taxonomy that includes "the gold label is wrong", which separates model weaknesses from dataset noise.
- I5. Treat sarcasm and humour as a distinct failure class, because surface hostile words often mislead the classifier in both directions.
For Mova
How these ideas could serve Mova, our small open language model — its files, stages and tests:
- I1 (learn): Silver trees agreed by witness parsers could be filtered the same way, keeping arcs only when parser confidences agree tightly and dropping high-variance sentences.
- I2 (frames): An insult or hostile speech-act detector could use such a class-distinctive word list as an explainable rule layer that names the word responsible for each flip.
- I3 (tree): The perceptron parser and gparse could be paired with a third parser of a different kind, with per-arc majority voting and each disagreement logged for explanation.
- I4 (learn): Evaluation reports could add a fixed error-category audit with an explicit annotation-noise bucket, so self-induced repair rules are not built from bad gold data.
- I5 (frames): The irony module could mark utterances with banter cues, so offensive-word evidence is weighed differently before deciding the speech act.
Fields, topics and concepts
📚 Shelves 4The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksSocial Sciences · 1,772 worksCommunication · 97 works
🧭 Topics 3Research subjects and languages the work is about.English · 2,263 worksSentiment & emotion · 972 worksSemitic languages · 2,908 works
Cite
Cite as Sabit Hassan, Younes Samih, Hamdy Mubarak and Ahmed Abdelali. 2020. ALT at SemEval-2020 Task 12: Arabic and English Offensive Language Identification in Social Media. Proceedings of the Fourteenth Workshop on Semantic Evaluation.
@inproceedings{hassan2020alt,
title = {{ALT at SemEval-2020 Task 12: Arabic and English Offensive Language Identification in Social Media}},
author = {Sabit Hassan, Younes Samih, Hamdy Mubarak and Ahmed Abdelali},
booktitle = {Proceedings of the Fourteenth Workshop on Semantic Evaluation},
year = {2020},
doi = {10.18653/v1/2020.semeval-1.249},
url = {https://doi.org/10.18653/v1/2020.semeval-1.249}
}References
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