Advances in the Automatic Lemmatization of Old English: Class IV Strong Verbs (L-Y)
Paper · 2023 · Roberto Torre
Summary
Old English is highly inflected, has no spelling standard, and lacks a lemmatized corpus. Standard data-driven lemmatizers and taggers therefore cannot be applied, and NLP work on the language stalls. Torre addresses one slice of this problem: class IV strong verbs whose lemmas begin with L through Y. Instead of learning from annotated data, he builds a rule-based lemmatizer within the Morphological Generation framework. Starting from each lemma, a set of algorithms produces the inflected forms, stem and ending variants caused by morphophonology and dialect, and derived (prefixed) counterparts. Each generated form is then checked against the YCOE (Taylor et al. 2003) and the DOEC (Healey et al. 2004). Forms found there count as attested and inherit the lemma that produced them. The process works on types only; disambiguating tokens in context is left for a later step. The result is a set of dependable form–lemma links plus explicitly flagged zones of ambiguity and mismatch for manual review. This matters for OE lexicography, where the DOE has so far reached only the letter I.
Key points
- Scope: OE class IV strong verbs, lemmas L–Y. The pipeline generates forms, validates them against corpora, and assigns lemmas, all at the type level.
- The generation algorithms model inflection, derivation, morphophonological change, and diatopic (dialectal) variation.
- The reference corpora are large but unlemmatized: DOEC has about 3,000,000 words and YCOE about 1,500,000. Among the smaller ones are the Helsinki Corpus (300,000) and York-Helsinki's parsed collection of OE verse (70,000).
- The work belongs to the Nerthus project. Its lemmatized ParCorOEv2 holds about 110,000 records, with a planned 300,000, and draws on the Knowledge Base of OE (KBOE).
- The outcome is successful form–lemma associations for attested forms, alongside an inventory of ambiguous cases and mismatches.
Interesting ideas
- I1. Generate-then-attest: rules expand every lemma into its full paradigm, and only forms that actually occur in a corpus are kept, so each surviving form carries its lemma by construction and overgeneration is filtered out cheaply.
- I2. Separating type-level lemmatization from token-level disambiguation lets a lexicon offer all candidate lemmas first, while choosing among them is deferred to a context-aware step.
- I3. Variation is handled as separate composable layers (inflection, sound/spelling change, dialect, derivation), and derived forms are built from the simplex paradigm rather than listed independently.
- I4. Ambiguous and mismatched outputs are treated as a deliverable, a list of cases flagged for human review, rather than as noise to hide.
For Mova
How these ideas could serve Mova, our small open language model — its files, stages and tests:
- I1 (tokens): Build the irregular-form and lemma tables in crate en by generating paradigms and keeping forms seen in treebank text, so every lemma can be traced to the rule that produced it.
- I2 (tokens): Keep a type lexicon listing every candidate lemma for a surface form, and let the tagger or the UD tree pick one, so ambiguity stays visible rather than being silently resolved.
- I3 (tokens): Derive prefixed verbs such as re- or out- forms from their base paradigms, and treat British/American spelling as its own variant layer instead of storing duplicates.
- I4 (learn): Route generated forms that match several lemmas, or none, into a review queue, and reuse confirmed failures as negative controls when evaluating the lemmatizer.
Institutions
Fields, topics and concepts
📚 Shelves 5The 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 worksLiterature and Literary Theory · 519 works
🧭 Topics 3Research subjects and languages the work is about.English · 2,263 worksMorphology · 405 worksHistorical linguistics & language change · 249 works
Cite
Cite as Roberto Torre. 2023. Advances in the Automatic Lemmatization of Old English: Class IV Strong Verbs (L-Y). Atlantis 45.
@inproceedings{torre2023advances,
title = {{Advances in the Automatic Lemmatization of Old English: Class IV Strong Verbs (L-Y)}},
author = {Roberto Torre},
booktitle = {Atlantis 45},
year = {2023},
doi = {10.28914/atlantis-2023-45.2.02},
url = {https://doi.org/10.28914/atlantis-2023-45.2.02}
}References
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- Received 27 August 2021 Roberto Torre Alonso is a Lecturer at the University of La Rioja, Spain. He is a member of the Functional Grammars Research Group at the same university and is currently participating in the development of ParCorOEv2. An Open Access Annotated Parallel Corpus Old English-English. His research interests include Old English morphology, the semantic-syntactic interrelation of Old English verbs and Old English verb lemmatization. find
- Revised version accepted 3 October 2022 find
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