The goal of aggregated search is to provide integrated search across multiple heterogeneous search services in a unified interface--a single query box and a common presentation of results. In the web search domain, aggregated search systems are responsible for integrating results from specialized search services, or verticals, alongside the core web results. For example, search portals such as Google, Bing, and Yahoo provide access to vertical search engines that focus on different types of media (images and video), different types of search tasks (search for local businesses and online...