This is a learning-to-rank pipeline, which is a part of the project where we study applicability of k-nearest neighbor search methods in IR and QA applications. For more details, please, check the Wiki page.
In particular, it includes the software for the paper L. Boytsov, D. Novak, Y. Malkov, E. Nyberg (2016). Off the Beaten Path: Let’s Replace Term-Based Retrieval with k-NN Search, to appear in proceedings CIKM'16. It can be also used to partially reproduce results from the paper: M Surdeanu, M Ciaramita, H Zaragoza. Learning to rank answers to non-factoid questions from web collections Computational Linguistics, 2011