In addition to<cite> [4]</cite> , we also implement several other strong baselines to better evaluate the e ectiveness of our model: 1) BM25; 2) VSM: Vector Space Model that was used in<cite> [4]</cite> ; 3) DESM: Dual Embedding Space Model which is a recent embedding based retrieval model [12] ; and <cite>4</cite>) LMD-LDA: Language modeling with LDA smoothing which is a recent extension of the LMD to also account for the latent topics [10] .