We were able to measure a translation improvement for all sizes of training corpora, under both the single word and multi-word conditions, except for the largest Spanish-English corpus.
we can extend the definition of the paraphrase probability to include multiple corpora, as follows: where c is a parallel corpus from a set of parallel corpora C. multiple corpora may be used by summing over all paraphrase probabilities calculated from a single corpus (as in Equation 1) and normalized by the number of parallel corpora.