Tharwa: A Large Scale Dialectal Arabic - Standard Arabic - English Lexicon
Paper · 2014 · Mona Diab, Mohamed Al-Badrashiny, Maryam Aminian et al.
Summary
Dialectal Arabic (DA), and Egyptian Arabic (EGY) in particular, is common in online text. Most Arabic NLP tools, however, are built for Modern Standard Arabic (MSA) and perform much worse on dialects. DA and MSA differ in phonology, morphology and vocabulary. Many written forms look the same across varieties but mean different things. Before this work, no wide-coverage resource linked dialect, standard Arabic and English.
The authors built Tharwa, a lemma-based three-way EGY–MSA–English lexicon. It merges a paper dictionary (Hinds-Badawi), the LDC's ECAL, and the lexica behind the CALIMA and SAMA analyzers. Each EGY entry is written in the CODA standardized spelling and fully diacritized. Entries also list attested spelling variants, POS, gender, number, rationality, root and morphological pattern. Gaps were filled manually and semi-automatically, and several rounds of quality control were applied.
The result has over 73,000 EGY entries and is publicly available. It already helps downstream tools, namely the Elissa DA-to-MSA translation system and the AIDA dialect identifier. Tharwa is meant as a nucleus for adding other Arabic dialects.
Key points
- Source resources:
- BADAWI: 31,548 EGY–English entries.
- ECAL: about 66K inflected EGY entries and about 36K lemmas, the same list CALIMA covers.
- SAMA-LEX: about 41K MSA lemmas, reduced to about 37K once semantic id markers are dropped.
- Lemma convention and tags:
- Nominal lemmas use the 3rd person singular masculine form.
- Verbal lemmas use the perfective 3rd person form.
- The tagset has 34 POS tags, including a vbn tag for deverbal nouns.
- EGY–MSA lexical relations fall into four types: identical, semantic cognates, homographs/homophones, and distinct words. Of the entries, 13.2% are homographs that carry extra EGY senses and 38.9% are completely distinct from MSA.
- Elissa: Tharwa-based MSA paraphrasing raised Arabic→English BLEU from 37.2 to 38.1 on dev, and yielded an absolute improvement of 1.4 BLEU points on an unseen held-out test set.
- AIDA: token/sentence dialect identification through MADAMIRA/CALIMA reached 76.2%. The majority baselines were 51.4% (MSA) and 45.6% (EGY).
Interesting ideas
- I1. Each entry is keyed on one conventionalized spelling (CODA), and the naturally occurring spelling variants are stored next to it. Normalization stays explicit and reversible instead of silently erasing variation.
- I2. Words shared between two language varieties are sorted into identical, regular cognate, false-friend homograph, or truly distinct. This shows exactly where naive transfer from one variety will mislead.
- I3. Patterns are recorded at two levels: a deep morphological pattern and a surface morpho-phonological one. Every surface-form entry is also linked back to its lemma, which keeps each analysis traceable.
- I4. Entries are checked from several independent angles: automatic consistency metrics, versioned edits, crowdsourcing, triangulation through parallel corpora, and native annotators.
- I5. The standard-language equivalent is given in the same inflectional form as the dialect entry, so a translation can substitute words without re-inflecting them.
For Mova
How these ideas could serve Mova, our small open language model — its files, stages and tests:
- I1 (tokens): The lemma lexicon in crate en could keep one canonical form plus attested variants (British/American, informal, misspelled), so the tagger can explain which variant it mapped.
- I2 (tree): During UD dialect conversion between treebanks, label and relation correspondences could be classified the same way, flagging "same label, different meaning" cases for special rules.
- I3 (tokens): English morphology could store the underlying morpheme pattern alongside its surface realization (e.g. consonant doubling before -ed), making each lemmatization step explainable.
- I4 (learn): Lexical facts in the compiled knowledge could be accepted only when independent witnesses agree, reusing the silver-data agreement idea for the lexicon itself.
- I5 (back): When generating or translating through the meta-world, aligned forms could be stored per inflection rather than per lemma, giving direct and explainable surface substitutions.
Institutions
Fields, topics and concepts
📚 Shelves 4The field of science this work belongs to (OpenAlex fields).Computer Science · 18,614 worksArtificial Intelligence · 17,965 worksArts and Humanities · 17,450 worksLanguage and Linguistics · 17,296 works
🧭 Topics 2Research subjects and languages the work is about.English · 2,379 worksSemitic languages · 3,066 works
Cite
Cite as Mona Diab, Mohamed Al-Badrashiny, Maryam Aminian, Mohammed Attia, Heba Elfardy, Nizar Habash, Abdelati Hawwari, Wael Salloum, Pradeep Dasigi and Ramy Eskander. 2014. Tharwa: A Large Scale Dialectal Arabic - Standard Arabic - English Lexicon. Proceedings of the Ninth International Conference on Language Resources and Evaluation (LREC'14).
@inproceedings{diab2014tharwa,
title = {{Tharwa: A Large Scale Dialectal Arabic - Standard Arabic - English Lexicon}},
author = {Mona Diab, Mohamed Al-Badrashiny, Maryam Aminian, Mohammed Attia, Heba Elfardy, Nizar Habash, Abdelati Hawwari, Wael Salloum, Pradeep Dasigi and Ramy Eskander},
booktitle = {Proceedings of the Ninth International Conference on Language Resources and Evaluation (LREC'14)},
year = {2014},
doi = {10.63317/2fmjsvgfookr},
url = {https://doi.org/10.63317/2fmjsvgfookr}
}References
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