A Neural Model for Part-of-Speech Tagging in Historical Texts
What it is about
Historical texts differ from modern ones in spelling, morphology and syntax, so taggers trained on modern text fail on them. The usual fix is a spelling-normalisation stage that maps old spellings to modern ones before tagging. The paper trains a character-level bidirectional GRU tagger that reads historical text directly. Its training loss adds a term that keeps the representation of an original spelling close to that of its normalised form. Tests cover Swedish verb identification (Gender and Work corpus, F-score 0.8529 on test with the POS weight 0.8, against 0.8601 for the SMT-normalisation pipeline) and German POS tagging on GerManC (early modern German, 1650-1800). On German the neural tagger is almost level with the normalisation pipeline: the difference is five tokens out of 4,845. The error analysis finds that the Swedish problems come from morphology and syntax, not only spelling.
Ideas
- I1.
en/src/emode.rsand 2. Spelling, print conventions and tokens: measure tagging accuracy on Early Modern English sentences with and without the closed form table applied beforeen/src/ptag.rs. The paper's result says normalisation is a strong baseline, so this is the comparison to beat. - I2. The paper's Swedish errors include the first-person-plural ending -om, which a spelling rule confuses with other endings. Write the analogous closed list for EModE verb endings (
-eth,-est,-st) into 4. Verb endings: -est, -st, -eth, -th and count how often each ending is confused with a noun or an adjective. - I3. The German homily shows that infinitives and first-person plurals are homonymous. Build a count table of English homonym pairs in EModE (for example
doas base and as plural) and use the tree context to choose, with the choice logged so each decision can be explained.
For Mova
The chapters are 2. Spelling, print conventions and tokens, 04-verb-endings.md and 12-mova-pipeline.md. The code is en/src/emode.rs (closed table), en/src/ptag.rs (tagger) and tools/gutenberg (texts). The measure: tag accuracy on a held-out set of EModE lessons, with and without the table, run twice. The neural model is not for Mova; the normalisation-versus-direct comparison and the error categories are.
Cite
@inproceedings{hardmeier2016neural,
title = {{A Neural Model for Part-of-Speech Tagging in Historical Texts}},
author = {Hardmeier, Christian},
booktitle = {Proceedings of COLING 2016, the 26th International Conference on Computational Linguistics: Technical Papers},
year = {2016},
url = {https://aclanthology.org/C16-1088/}
}References
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