Temporal-Textual Retrieval: Time and Keyword Search in Web Documents

As the web ages, many web documents become relevant only to certain time periods, such as web-pages containing news and events or those documenting natural phenomena. Hence, to retrieve the most relevant pages, in addition to providing the relevant keywords, one may desire to identify the relevant time period(s) as well, e.g., "Barack Obama 1980-1985". Unfortunately, not much work has been done by industry or academia to support this type of searches. To the best of our knowledge, the only way that some search engines exploit the time information in the user query is to filter out those resulting web pages whose publication/modification time are not within the queried time interval. In this paper, we propose a new indexing and ranking framework for temporal-textual retrieval. The framework leverages the classical vector space model and provides a complete scheme for indexing, query processing and ranking of the temporal-textual queries. We propose a variety of approaches to exploit popular keyword and temporal index structures. We present a novel hybrid index structure which indexes both the temporal and the textual aspects of the documents in a unified, integrated manner. We also study how to rank documents by seamlessly combining their temporal and textual features. We develop a new scoring schema called temporal tf-idf to compute the temporal relevance of a document to a query, and we combine this score with the textual relevance to compute the overall relevance score of the document to the query. We present both a cost model analysis and an extensive set of experiments over real-world datasets (New York Times Annotated Corpus and Freebase) to evaluate the proposed framework and demonstrate its efficiency and effectiveness.