The Defense Advanced Research Projects Agency (DARPA) has opened its Shredder Challenge to find better ways to piece together shredded documents that troops discover in warzones. Participants can compete to win $50,000 with overall winners and prizes awarded on the number and difficulty of the problems solved. The challenge includes five separate puzzles with increasing complexity in the number of documents, the subject matter and the method of shredding. Competitors must provide the answer to a puzzle embedded in the content of the reconstructed document. Winners will be announced the week of December 5. For more information and to register, visit the website.