Hierarchical neural query suggestion with an attention mechanism

Query suggestions help users of a search engine to refine their queries. Previous work on query suggestion has mainly focused on incorporating directly observable features such as query co-occurrence and semantic similarity. The structure of such features is often set manually, as a result of which hidden dependencies between queries and users may be ignored. We propose an Attention-based Hierarchical Neural Query Suggestion (AHNQS) model that uses an attention mechanism to automatically capture user preferences. AHNQS combines a session-level neural network and a user-level neural network into a hierarchical structure to model the short- and long-term search history of a user. We quantify the improvements of AHNQS over state-of-the-art recurrent neural network-based query suggestion baselines on the AOL query log dataset, with improvements of up to 9.66% and 12.51% in terms of Recall@10 and MRR@10, respectively; improvements are especially obvious for short sessions and inactive users with few search sessions.