CLEF keynote slides

The slides of the CLEF keynote can be downloaded below

A case for search specialization and search delegation

Evaluation conferences like CLEF, TREC and NTCIR are important for the field, and keep being important because there is no “one-size-fits-all” for search engines. Different domains need different ranking approaches: For instance, Web search benefits from analyzing the link graph; Twitter search benefits from retweets and likes; Restaurant search benefits from geo-location and reviews; Advertisement search need bids and click-through, etc. Researching many domains will learn us more about the need and the value of the specialization of search engines, and about approaches that can quickly learn rankings for new domains using for instance learning-to-rank and clever feature selection.
A search engine that provides results from multiple domains, therefore better delegates its queries to specialized search engines. This brings up unique research questions on how to best select a specialized search engine. The TREC Federated Web Search track, that ran in 2013 and 2014, studied these questions in two tasks: the resource selection task studied how to select, given a query but before seeing the results for the query, the top specialized search engines for a query. The vertical selection task studied how to select the top domains from a predefined set of domains such as news, video, Q&A, etc.
I will present the lessons that we learned from running the Federated Web Search track, focusing on successful approaches to resource selection and vertical selection. I will conclude the talk by discussing our steps to take this work to full practice by running the University of Twente’s search engine as a federation of more than 30 smaller search engines, including local databases with news, courses, publications, as well as results from social media like Twitter and YouTube. The engine that runs U. Twente search is called Searsia and is available as open source software at:

[download slides]

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