Unsupervised concept discovery in Hebrew using simple unsupervised word prefix segmentation for Hebrew and Arabic

Fully unsupervised pattern-based methods for discovery of word categories have been proven to be useful in several languages. The majority of these methods rely on the existence of function words as separate text units. However, in morphology-rich languages, in particular Semitic languages such as Hebrew and Arabic, the equivalents of such function words are usually written as morphemes attached as prefixes to other words. As a result, they are missed by word-based pattern discovery methods, causing many useful patterns to be undetected and a drastic deterioration in performance. To enable high quality lexical category acquisition, we propose a simple unsupervised word segmentation algorithm that separates these morphemes. We study the performance of the algorithm for Hebrew and Arabic, and show that it indeed improves a state-of-art unsupervised concept acquisition algorithm in Hebrew.