Coerced Markov Models for Cross-lingual Lexical-tag Relations

We introduce the Coerced Markov Model (CMM) to model the relationship between the lexical sequence of a source language and the tag sequence of a target language, with the objective of constraining search in statistical transfer-based machine translation systems. CMMs differ from standard hidden Markov models in that state sequence assignments can take on values coerced from external sources. Given a Chinese sentence, a CMM can be used to predict the corresponding English tag sequence, thus constraining the English lexical sequence produced by a translation model. The CMM can also be used to score competing translation hypotheses in N-best models. Three fundamental problems for CMM designed are discussed. Their solutions lead to the training and testing stages of CMM. The Hong Kong University of Science & Technology Technical Report Series Department of Computer Science