Bilingual Lexicon Extraction at the Morpheme Level Using Distributional Analysis

Bilingual lexicon extraction from comparable corpora is usually based on distributional methods when dealing with single word terms (SWT). These methods often treat SWT as single tokens without considering their compositional property. However, many SWT are compositional (composed of roots and affixes) and this information, if taken into account can be very useful to match translational pairs, especially for infrequent terms where distributional methods often fail. For instance, the English compound \textit{xenograft} which is composed of the root \textit{xeno} and the lexeme \textit{graft} can be translated into French compositionally by aligning each of its elements (\textit{xeno} with \textit{x{\'e}no} and \textit{graft} with \textit{greffe}) resulting in the translation: \textit{x{\'e}nogreffe}. In this paper, we experiment several distributional modellings at the morpheme level that we apply to perform compositional translation to a subset of French and English compounds. We show promising results using distributional analysis at the root and affix levels. We also show that the adapted approach significantly improve bilingual lexicon extraction from comparable corpora compared to the approach at the word level.