Learning to Rank Answers to Non-Factoid Questions from Web Collections Mihai Surdeanu author Massimiliano Ciaramita author Hugo Zaragoza author 2011-06 text journal article Computational Linguistics continuing MIT Press Cambridge, MA periodical academic journal surdeanu-etal-2011-learning 10.1162/COLI_a_00051 https://aclanthology.org/J11-2003/ 2011-06 37 2 351 383