Orthonormal Explicit Topic Analysis for Cross-Lingual Document Matching

Cross-lingual topic modelling has applications in machine translation, word sense disambiguation and terminology alignment.Multilingual extensions of approaches based on latent (LSI), generative (LDA, PLSI) as well as explicit (ESA) topic modelling can induce an interlingual topic space allowing documents in different languages to be mapped into the same space and thus to be compared across languages.In this paper, we present a novel approach that combines latent and explicit topic modelling approaches in the sense that it builds on a set of explicitly defined topics, but then computes latent relations between these.Thus, the method combines the benefits of both explicit and latent topic modelling approaches.We show that on a crosslingual mate retrieval task, our model significantly outperforms LDA, LSI, and ESA, as well as a baseline that translates every word in a document into the target language.