Modeling morpheme triplets with a three-level hierarchical Dirichlet process

Abstract

Morphemes are not independent units and attached to each other based on morphotactics. However, they are assumed to be independent from each other to cope with the complexity in most of the models in the literature. We introduce a language independent model for unsupervised morphological segmentation using hierarchical Dirichlet process (HDP). We model the morpheme dependencies in terms of morpheme trigrams in each word. Trigrams, bigrams and unigrams are modeled within a three-level HDP, where the trigram Dirichlet process (DP) uses the bigram DP and bigram DP uses unigram DP as the base distribution. The results show that modeling morpheme dependencies improve the F-measure noticeably in English, Turkish and Finnish.