  The Paraphrase Database (PPDB; Ganitkevitch et al., 2013) is an extensive
semantic resource, consisting of a list of phrase pairs with (heuristic)
confidence estimates. However, it is still unclear how it can best be used, due
to the heuristic nature of the confidences and its necessarily incomplete
coverage. We propose models to leverage the phrase pairs from the PPDB to build
parametric paraphrase models that score paraphrase pairs more accurately than
the PPDB's internal scores while simultaneously improving its coverage. They
allow for learning phrase embeddings as well as improved word embeddings.
Moreover, we introduce two new, manually annotated datasets to evaluate
short-phrase paraphrasing models. Using our paraphrase model trained using
PPDB, we achieve state-of-the-art results on standard word and bigram
similarity tasks and beat strong baselines on our new short phrase paraphrase
tasks.
