---
title: "Parser combinators for Tigrinya and Oromo morphology — Littell 2018"
description: "The authors write rule-based morphological parsers for Tigrinya and Oromo as parser combinators in Python, not as… 16 references, cited by 1 paper here."
authors: ["Patrick Littell", "Tom McCoy", "Na-Rae Han", "Shruti Rijhwani", "Zaid Sheikh", "David Mortensen", "Teruko Mitamura", "Lori Levin"]
year: 2018
venue: "Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018)"
source: "https://aclanthology.org/L18-1611/"
doi: "10.63317/268voan22369"
licence: "CC BY-NC 4.0 (ELRA, LREC proceedings)"
licence_url: "https://creativecommons.org/licenses/by-nc/4.0/"
summary_licence: "Elamur Cosmic License"
canonical: "https://research.elamur.ai/free/en/papers/littell-2018-parser-combinators-tigrinya-oromo-morphology/"
---
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# Parser combinators for Tigrinya and Oromo morphology

**Authors:** [Patrick Littell](https://md.research.elamur.ai/free/en/authors/patrick-littell/); Tom McCoy; [Na-Rae Han](https://md.research.elamur.ai/free/en/authors/na-rae-han/); [Shruti Rijhwani](https://md.research.elamur.ai/free/en/authors/shruti-rijhwani/); Zaid Sheikh; [David Mortensen](https://md.research.elamur.ai/free/en/authors/david-r-mortensen/); [Teruko Mitamura](https://md.research.elamur.ai/free/en/authors/teruko-mitamura/); [Lori Levin](https://md.research.elamur.ai/free/en/authors/lori-levin/) · **Year:** 2018 · **Venue:** Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018) **Link:** [aclanthology.org/L18-1611](https://aclanthology.org/L18-1611/) · library `lingbulk-2018-littell-parser-combinators-tigrinya-oromo-morphology` · **Licence:** [CC BY-NC 4.0](https://creativecommons.org/licenses/by-nc/4.0/) (ELRA, LREC proceedings) — summary only

[**1** citations](https://openalex.org/works?filter=cites:W2805334312) OpenAlex, 2026-10-14 · [**1** citations in our library](https://md.research.elamur.ai/free/en/papers/littell-2018-parser-combinators-tigrinya-oromo-morphology/cited-by/) of the 140,884 papers whose bibliographies we read · [Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018)](https://aclanthology.org/volumes/L18-1/) · [licence](https://creativecommons.org/licenses/by-nc/4.0/)

- [Publisher's page](https://aclanthology.org/L18-1611/)
- [PDF](https://aclanthology.org/L18-1611.pdf)
- [DOI 10.63317/268voan22369](https://doi.org/10.63317/268voan22369)
- [OpenAlex](https://openalex.org/W2805334312)

**Authors (8)**

1. [Patrick Littell](https://openalex.org/A5045031910) [ORCID](https://orcid.org/0000-0002-7173-0225) · [Semantic Scholar](https://www.semanticscholar.org/author/3070462) · h 15 · 1,208 citations · 75 works
2. [Tom McCoy](https://openalex.org/A5081894510) [Semantic Scholar](https://www.semanticscholar.org/author/145534175) · h 4 · 1,080 citations · 10 works
3. [Na-Rae Han](https://openalex.org/A5025158167) [ORCID](https://orcid.org/0000-0002-8771-0173) · [Semantic Scholar](https://www.semanticscholar.org/author/38187902) · h 11 · 681 citations · 37 works
4. [Shruti Rijhwani](https://openalex.org/A5014428509) [Semantic Scholar](https://www.semanticscholar.org/author/7391530) · h 16 · 1,900 citations · 63 works
5. [Zaid Sheikh](https://openalex.org/A5111476836) [Semantic Scholar](https://www.semanticscholar.org/author/38599655) · h 6 · 131 citations · 16 works
6. [David Mortensen](https://openalex.org/A5059859009) [ORCID](https://orcid.org/0000-0002-3927-6851) · [Semantic Scholar](https://www.semanticscholar.org/author/3407646) · h 15 · 1,188 citations · 146 works
7. [Teruko Mitamura](https://openalex.org/A5052956256) [Semantic Scholar](https://www.semanticscholar.org/author/1706595) · h 32 · 4,061 citations · 254 works
8. [Lori Levin](https://openalex.org/A5008257790) [ORCID](https://orcid.org/0000-0003-0831-3063) · [Semantic Scholar](https://www.semanticscholar.org/author/1686960) · h 27 · 2,658 citations · 141 works

Citations and author metrics: OpenAlex, 2026-10-14; authors with the same name are not always told apart.

## What it is about

The authors write rule-based morphological parsers for Tigrinya and Oromo as parser combinators in Python, not as finite-state transducers. The work was done within a few days during the LoReHLT17 surprise-language evaluation. One grammar yields several outputs at once: breakdown, lemma, gloss and a natural English gloss, ranked by penalties. Tigrinya internal plurals are handled by regular-expression templates over consonant classes, and a Cost channel penalises over-analysis, for example place names that end in -a. The cost of finite-state efficiency is accepted. The evaluation is downstream: adding lemmatization raised entity detection and linking (typed_mention_ceaf_plus, Tigrinya 0.478 to 0.521, Oromo 0.355 to 0.376) and situation-frame F1 (Tigrinya 0.325 to 0.333, Oromo 0.047 to 0.086).

## For Mova

- I1. A cost channel for segmentation in `tools/hbo`: each prefix or suffix cut carries a penalty, so an unsplit word wins unless the stem is in the lexicon. This stops over-segmentation of names, the same way the paper stops `ʔuɡanɨda` from being read as a possessive `-a`. Where: the ranking of the `lex` and `pre` splits.
- I2. Templates as explicit patterns for Hebrew and Aramaic root-and-pattern plurals: a consonant-class pattern over the root triple, applied after the lexicon lookup, as the paper does for Tigrinya internal plurals. Where: [languages/hbo/04-noun.md](https://mova.elamur.ai/free/en/docs/languages/hbo/04-noun/), [languages/arc/nouns.md](https://mova.elamur.ai/free/en/docs/languages/arc/nouns/), implemented as a fallback in `tools/hbo`.
- I3. Measure every added rule as the paper does, by its downstream effect (here, the lemma versus the word), with a before/after table. A rule is kept only if the downstream number rises on held-out data. Where: [languages/hbo/13-mova-tools.md](https://mova.elamur.ai/free/en/docs/languages/hbo/13-mova-tools/).

I1 goes into `tools/hbo` (segmenter ranking). I2 goes into [languages/hbo/04-noun.md](https://mova.elamur.ai/free/en/docs/languages/hbo/04-noun/) and [languages/arc/nouns.md](https://mova.elamur.ai/free/en/docs/languages/arc/nouns/), with its code in `tools/hbo`. I3 is the evaluation rule for [languages/hbo/13-mova-tools.md](https://mova.elamur.ai/free/en/docs/languages/hbo/13-mova-tools/).

## Institutions

[🎓**Carnegie Mellon University** Pittsburgh · United States 278 works · 138,810 citations](https://md.research.elamur.ai/free/en/universities/carnegie-mellon-university/) · [🎓**Johns Hopkins University** Baltimore · United States 151 works · 84,111 citations](https://md.research.elamur.ai/free/en/universities/johns-hopkins-university/) · [🎓**University of Pittsburgh** Pittsburgh · United States 32 works · 20,612 citations](https://md.research.elamur.ai/free/en/universities/university-of-pittsburgh/) · [🏛️**National Research Council Canada** Ottawa · Canada 36 works · 16,873 citations](https://md.research.elamur.ai/free/en/government/national-research-council-canada/)

Topics[Morphology](https://md.research.elamur.ai/free/en/topics/morphology/) · [Semitic languages](https://md.research.elamur.ai/free/en/topics/semitic-languages/)

## Cite

Cite as Patrick Littell, Tom McCoy, Na-Rae Han, Shruti Rijhwani, Zaid Sheikh, David Mortensen, Teruko Mitamura and Lori Levin. 2018. Parser combinators for Tigrinya and Oromo morphology. Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018).

The paper itself, not this card. BibTeX from the library's record of the work. [DOI 10.63317/268voan22369](https://doi.org/10.63317/268voan22369)

```bibtex
@inproceedings{littell2018parser,
  title = {{Parser combinators for Tigrinya and Oromo morphology}},
  author = {Patrick Littell, Tom McCoy, Na-Rae Han, Shruti Rijhwani, Zaid Sheikh, David Mortensen, Teruko Mitamura and Lori Levin},
  booktitle = {Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018)},
  year = {2018},
  doi = {10.63317/268voan22369},
  url = {https://doi.org/10.63317/268voan22369}
}
```

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## References

16 references, 2 of them with a card of ours. ↗ leads to the work, «find» searches for one we have no id for yet.

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