Motivating Example On october 4.2012. the first presidential debate between President barack obama and Governor Mitt romney triggered more than 10 million Wicker tweets within two hours How to explore the large volumes of data and extract useful information or knowledge for future actions?Motivating Example On October 4, 2012, the first presidential debate between President Barack Obama and Governor Mitt Romney triggered more than 10 million tweets within two hours. 16 How to explore the large volumes of data and extract useful information or knowledge for future actions?