Diversifying Search Results Using Time - An Information Retrieval Method for Historians

Getting an overview of a historic entity or event can be difficult in search results, especially if important dates concerning the entity or event are not known beforehand. For such information needs, users benefit if returned results covered diverse dates, thus giving an overview of what has happened throughout history. Such a method can be a building block for applications, for instance, in digital humanities. We describe an approach to diversify search results using temporal expressions (e.g., 1990s) from their contents. Our approach first identifies time intervals of interest to the given keyword query based on pseudo-relevant documents. It then re-ranks query results so as to maximize the coverage of identified time intervals. We present a novel and objective evaluation for our proposed approach. We test the effectiveness of our methods on The New York Times Annotated corpus and the Living Knowledge corpus, collectively consisting of around 6 million documents. Using history-oriented queries and encyclopedic resources we show that our method is able to present search results diversified along time.