WebPIE: a Web-scale Parallel Inference Engine

The Semantic Web [1] extends the World Wide Web by providing well-defined semantics to information and services. Through these semantics machines can “understand” the Web, making it possible to query and reason over Web information, treating the Web as if it were a giant semi-structured database. Over the recent years, large volumes of data have been published in a Semantic Web format, constituting a valuable resource for researchers across several fields: in medicine, there are dozens of datasets that comprise protein sequence and functional information, biomedical article citations, gene information and more. The US and UK governments are putting major effort in making public information more accessible by providing it in Semantic Web formats . General knowledge extracted from Wikipedia 3 and geographical knowledge 4 is also available. Semantic Web data is expressed in statements, also known as triples. Available data is quickly outgrowing the computational capacity of single machines and of standard indexing techniques. In March 2009, around 4 billion statements were available. In the following 9 months this number had tripled to 13 billion statements and the growth continues. A statement consists of a sequence of three terms: subject, predicate and object. An example is: