A POMDP model for content-free document re-ranking

Abstract

Log-based document re-ranking is a special form of session search. The task re-ranks documents from Search Engine Results Page (SERP) according to the search logs, in which both the search activities from other users and personalized query log for a user are available. The purpose of re-ranking is to provide the user with a new and better ordering of the initial retrieved documents. We test the system on the WSCD 2014 dataset, in which the actual content of the queries and documents are not available due to privacy concerns. The challenge is to perform effective re-ranking purely based on user behaviors, such as clicks and query reformulations rather than document content. In this paper, we propose to model log-based document re-ranking as a Partially Observable Markov Decision Process (POMDP). Experiments on the document re-ranking task show that our approach is effective and outperforms the baseline rankings provided by a commercial search engine.