More than 5,000 teams have signed up to compete in a Defense Advanced Research Projects Agency's (DARPA's) shredder challenge, and those that have solved the first two levels of the test have mainly used manual methods to reassemble shredded pieces of paper. Now, the agency says, it will take computational methods to solve the rest.

DARPA introduced the so-called Shredder Challenge last week. The task is to reassemble five shredded documents and $50,000 will go to the winner, which will be judged on the number of problems solved and their degree of difficulty.

The aim of the challenge is to develop ways to reconstruct shredded documents that U.S. soldiers come across to use to gather intelligence information. The Department of Defense (DOD) also wants to try to discern how enemies might be reassembling U.S. documents by crowdsourcing this activity.

The Obama administration has made ample use of crowdsourcing and challenges to help the feds solve technology and other problems, even creating an entire website for agencies to post challenges for people to solve for a range of cash prizes.

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Sixteen teams have solved the first Shredder Challenge puzzle and two have solved the second, mainly by manual means--such as printing, cutting out and sorting by hand the various pieces of the puzzle--and "sheer patience and determination," DARPA Director Regina E. Dugan said in a statement Wednesday.

The first two problems contained 224 and 373 pieces, respectively, and some teams already have used algorithms to separate pieces individually before sorting them, according to DARPA.

The next three get considerably more difficult, however, and if someone were to come up with a computational, automated means for reconstructing shredded documents, they "could find an advantage" for solving them, Dugan said.

To solve puzzle 3, teams must sort through and reassemble 1,115 pieces of paper, while puzzle 4 has 2,340 pieces and puzzle 5 has 6,068 pieces.

Dugan said it will be a combination of using "powerful computation methods with shared tasking and the diverse insights of the crowd" that will decide the winner of the challenge.

The Shredder Challenge website has received close to 4 million hits since Oct. 27, and more than 5,000 teams have registered to participate. The challenge also has inspired a lot of chatter online, as the teams involved are using blogs and a forum on the challenge's website to discuss the challenge and its technical aspects, according to DARPA.

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