CLARIFICATION QUESTIONS SELECTION FOR CONVERSATIONAL SEARCH, TRAINED FROM HUMAN-TO-HUMAN CONVERSATIONS AND SOLUTION DOCUMENTS

Clarification-question selection, including: Receiving a search conversation that includes utterances by a user and by a conversational search system. Retrieving, from a solution documents database, text passages that are relevant to the search conversation. Retrieving, from a clarification questions database, for each of the text passages, candidate clarification questions that are relevant to both the respective text passage and the search conversation. Ranking the candidate clarification questions according to (a) a first deep learning model that outputs, for each of the candidate clarification questions, a score denoting a strength of association between the respective candidate clarification question and the search conversation, and/or (b) a second deep learning model that outputs, for each of the candidate clarification questions, a score denoting a strength of association between the respective candidate clarification question, the search conversation, and the text passage that was retrieved for the respective candidate clarification question.