Enabling queries on relational data on the Web

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While the World Wide Web provides public access to one of the largest and most heterogeneous data collections ever created, its querying capabilities have remained very much limited to keyword search. This reduces the efficiency of the search and the scope of the information that can be explored or retrieved. More specifically, a keyword search is not sufficient when the search is not bounded to a selection and involves join and set operations over the contents of the documents. For instance, a keyword search is not appropriate for querying relationships, and the Web contains relationships galore. Also, a keyword search is not very applicable when the granularity of the search result is smaller than a document, and the result is a more refined set of items or entities that satisfy some conditions.