By IANS
New York : A month after checkers was solved by a supercomputer, the machines have an answer to the Rubik’s Cube too. A high-speed machine at Northeastern University, Boston, has proved that any of the cubes – no matter how intangible they look – can be properly aligned within just 26 moves.
Till now, the best way to crack the Rubik’s Cube was in 27 moves. But Dan Kunkle and Prof Gene Cooperman at Northeastern University believe that with more work they could push the count even lower.
“We don’t yet have a proof that 25 moves suffice, but we have several new directions to try that we hope will get us there before the end of the year,” Kunkle was quoted as saying in The Daily Telegraph.
The ultimate solution to the Rubik’s cube has come closer thanks to hours of number crunching conducted on a supercomputer, which took 63 hours to crank out the proof.
The pair used a brute force method of trying various combinations in the computer, relying on an extra 7,000 gigabytes of storage. But the solution was cleverer than trying all possible because cranking through the 43 billion possible Rubik’s cube positions would take too long even for a supercomputer that can study 100 million configurations per second.
Instead, the scientists used a two-step technique in their calculations. Initially, they programmed the supercomputer to arrive at one of 15,000 half-solved solutions that they knew could be fully solved with a few extra moves.
This suggested that any disordered cube could be fully solved in a maximum of 29 moves, but that most cubes took 26 moves or fewer. The researchers then focussed on the small number of “problem” configurations that required more than 26 moves, using the supercomputer to search for the best way to fully solve them. As it turned out the supercomputer was able to fully solve all these problem cases in less than 26 moves.
The study brings scientists one step closer to finding “God’s Number”, which is the minimum number of moves needed to solve any disordered Rubik’s cube. It was so named by two researchers in 1982 because god would only need the smallest number of moves to solve a cube. Theoretical work suggests that God’s Number is in the “low 20s”.