YAMAMA: Yet Another Multi-Dialect Arabic Morphological Analyzer
Paper · 2016 · Salam Khalifa, Nasser Zalmout and Nizar Habash
Summary
Arabic morphological processing is hard: words carry many inflections, the script is orthographically ambiguous (about a dozen full analyses per word on average), and dialects such as Egyptian (EGY) sit alongside Modern Standard Arabic (MSA). Existing tools force a choice. MADAMIRA gives rich output (diacritics, lemma, POS, gloss, all inflectional features) but runs slowly. FARASA is fast but only segments words, and only for MSA.
YAMAMA keeps MADAMIRA's analyzers and output format but replaces its context-based disambiguation with a simple context-free model inspired by FARASA. Known words get their most frequent analysis from the training data, looked up in a precomputed dictionary. Unknown words are analyzed and ranked by lemma and tag unigram probabilities. All decisions are made once per word type rather than per token.
Trained and tested on PATB and the ARZ Treebank, YAMAMA is roughly five times faster than MADAMIRA on large text. Its accuracy is slightly lower for MSA, mainly in diacritization, and comparable or better for EGY. Machine translation quality barely changes. This makes it a practical middle point between speed and richness.
Key points
- Data and resources.
- Training and test data: PATB parts 1–3 (MSA) and the ARZ Treebank (EGY), using the splits from Diab et al. (2013).
- Out-of-vocabulary analysis uses the SAMA database for MSA and CALIMA ARZ for EGY.
- Accuracy and speed on the MSA test set.
- YAMAMA reaches ALL-features accuracy of 78.8 versus MADAMIRA's 86.0.
- The gap comes mostly from diacritization (81.0 vs 88.0).
- YAMAMA runs in 15.4 s against 57.7 s.
- EGY results. YAMAMA slightly beats MADAMIRA on ALL (79.3 vs 78.4) and wins on most features except POS.
- FARASA tokenization scheme.
- On MSA ATB, YAMAMA and MADAMIRA both score 98.7, while FARASA scores 89.6.
- On EGY, YAMAMA scores 94.4 against FARASA's 73.3.
- On WikiNews, all three systems are close.
- Large-corpus timing and MT.
- On 7.5M words of Gigaword, MADAMIRA took 2,305 s, YAMAMA 398 s and FARASA 99 s.
- In Moses SMT on the UN Corpus, YAMAMA scored 39.49 BLEU, close to MADAMIRA's 39.52 and above FARASA's 37.73.
Interesting ideas
- I1. Deciding analyses once per word type and then expanding back to tokens exploits a low type-to-token ratio on big corpora (3.7% at 8M words), which gives large speedups at no accuracy cost for that step.
- I2. A two-tier design: a lookup table of the most frequent analysis for known words, and for unknown ones, analyzer candidates ranked by the product of lemma and tag unigram probabilities, with the winner added back into the table.
- I3. Keep the rich analyzer and full output format, and swap only the disambiguation component, so downstream consumers notice no difference.
- I4. To compare systems with different conventions fairly, map every system's output and the gold data into one shared scheme, and report a normalized variant alongside it.
- I5. In extrinsic MT evaluation, rerun after dropping OOV words to separate one system's transliteration artifact from genuine segmentation quality.
For Mova
How these ideas could serve Mova, our small open language model — its files, stages and tests:
- I1 (tokens): The en crate could cache lemma/morphology decisions per surface form so that each form is resolved only once and reused across a corpus.
- I2 (tokens): Mova's lemmatizer could use this as a fast, explainable baseline, where each choice traces to either "most frequent in treebank" or "lemma×tag score".
- I3 (tokens): Mova could offer fast and accurate tagger modes behind one identical feature interface, so later stages run unchanged.
- I4 (learn): When scoring witness parsers that emit different UD dialects, first convert all of them and the gold trees to a common scheme, and report both strict and normalized scores.
- I5 (learn): Evaluations could include such ablation controls so that a single quirky failure mode does not dominate comparisons between components.
Institutions
Fields, topics and concepts
📚 Shelves 6The 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 worksSocial Sciences · 1,772 worksEducation · 203 works
🧭 Topics 2Research subjects and languages the work is about.Semitic languages · 2,908 worksMorphology · 405 works
Cite
Cite as Salam Khalifa, Nasser Zalmout and Nizar Habash. 2016. YAMAMA: Yet Another Multi-Dialect Arabic Morphological Analyzer. Proceedings of COLING 2016, the 26th International Conference on Computational Linguistics: System Demonstrations.
@inproceedings{khalifa2016yamama,
title = {{YAMAMA: Yet Another Multi-Dialect Arabic Morphological Analyzer}},
author = {Salam Khalifa, Nasser Zalmout and Nizar Habash},
booktitle = {Proceedings of COLING 2016, the 26th International Conference on Computational Linguistics: System Demonstrations},
year = {2016},
url = {https://aclanthology.org/C16-2047/}
}References
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