Svanhvít Lilja Ingólfsdóttir


2019

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Nefnir: A high accuracy lemmatizer for Icelandic
Svanhvít Lilja Ingólfsdóttir | Hrafn Loftsson | Jón Friðrik Daðason | Kristín Bjarnadóttir
Proceedings of the 22nd Nordic Conference on Computational Linguistics

Lemmatization, finding the basic morphological form of a word in a corpus, is an important step in many natural language processing tasks when working with morphologically rich languages. We describe and evaluate Nefnir, a new open source lemmatizer for Icelandic. Nefnir uses suffix substitution rules, derived from a large morphological database, to lemmatize tagged text. Evaluation shows that for correctly tagged text, Nefnir obtains an accuracy of 99.55%, and for text tagged with a PoS tagger, the accuracy obtained is 96.88%.

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Towards High Accuracy Named Entity Recognition for Icelandic
Svanhvít Lilja Ingólfsdóttir | Sigurjón Þorsteinsson | Hrafn Loftsson
Proceedings of the 22nd Nordic Conference on Computational Linguistics

We report on work in progress which consists of annotating an Icelandic corpus for named entities (NEs) and using it for training a named entity recognizer based on a Bidirectional Long Short-Term Memory model. Currently, we have annotated 7,538 NEs appearing in the first 200,000 tokens of a 1 million token corpus, MIM-GOLD, originally developed for serving as a gold standard for part-of-speech tagging. Our best performing model, trained on this subset of MIM-GOLD, and enriched with external word embeddings, obtains an overall F1 score of 81.3% when categorizing NEs into the following four categories: persons, locations, organizations and miscellaneous. Our preliminary results are promising, especially given the fact that 80% of MIM-GOLD has not yet been used for training.