--- title: "Parser combinators for Tigrinya and Oromo — Littell 2018" description: "The authors write rule-based morphological parsers for Tigrinya and Oromo as parser combinators in Python, not as finite-state transducers. The work was…" 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/lingbulk-2018-littell-parser-combinators-tigrinya-oromo-morphology/" --- [Elamur Research](https://md.research.elamur.ai/free/en/) · [this page in HTML](https://research.elamur.ai/free/en/papers/lingbulk-2018-littell-parser-combinators-tigrinya-oromo-morphology/) [home](https://md.research.elamur.ai/free/en/) / [papers](https://md.research.elamur.ai/free/en/papers/) / [2018](https://md.research.elamur.ai/free/en/papers/2018/page/3/) / Parser combinators for Tigrinya and Oromo morphology # Parser combinators for Tigrinya and Oromo morphology **Authors:** Patrick Littell; Tom McCoy; [Na-Rae Han](https://md.research.elamur.ai/free/en/authors/na-rae-han/); Shruti Rijhwani; Zaid Sheikh; David 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/lingbulk-2018-littell-parser-combinators-tigrinya-oromo-morphology/cited-by/) of the 140673 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 · 1208 citations · 75 works 2. [Tom McCoy](https://openalex.org/A5081894510) [Semantic Scholar](https://www.semanticscholar.org/author/145534175) · h 4 · 1080 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 · 1900 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 · 1188 citations · 146 works 7. [Teruko Mitamura](https://openalex.org/A5052956256) [Semantic Scholar](https://www.semanticscholar.org/author/1706595) · h 32 · 4061 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 · 2658 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). ## Ideas - 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/). ## For Mova 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/). ## Cite 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 = {Littell, Patrick and McCoy, Tom and Han, Na-Rae and Rijhwani, Shruti and Sheikh, Zaid and Mortensen, David and Mitamura, Teruko and Levin, Lori}, 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} } ``` - [← previous ParCorFull: a Parallel Corpus Annotated with Full Coreference](https://md.research.elamur.ai/free/en/papers/koltunski-2018-parcorfull-parallel-corpus-annotated-full/) - [next → Parsing Tweets into Universal Dependencies](https://md.research.elamur.ai/free/en/papers/ud-2018-liu-parsing-tweets-into-universal-dependencies/) - [↑ back to papers of 2018](https://md.research.elamur.ai/free/en/papers/2018/page/3/) ## 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. 1. 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