Introducing XGL - a lexicalised probabilistic graphical lemmatiser for isiXhosa

In this paper, a lexicalized probabilistic graphical lemmatiser for isiXhosa, XGL, is presented. An overview of isiXhosa lemmatisation issues is given, followed by a discussion on previous work in automated lemmatisation for isiXhosa. The paper continues to motivate for a machine learning lemmatiser for isiXhosa. IsiXhosa data used to train the lemmatiser is analyzed and the best features are identified from the analysis. The inner workings of XGL are detailed and evaluation results presented. XGL is shown to have achieved accuracy rates of 83.19% on a gold standard of word-lemma pairs, thereby outperforming similar lemmatisers such as LemmaGen's 80.6% and 73.13% from the CST lemmatiser when trained with 35000 word-lemma pairs.