Thirty-six years ago a new toy, a logic game, was invented by Erno Rubrik. All that time spent trying to get 26 cubes in the correct position seemed like a waste, until now. Discovery News reports:
An international team of researchers using computer time lent to them by Google has found every way the popular Rubik’s Cube puzzle can be solved, and showed it can always be solved in 20 moves or less.
The study is just the latest attempt by Rubik’s enthusiasts to figure out the secrets of the cube, which has proven to be altogether far more complicated that its jaunty colors might suggest.
At the crux of the quest has been a bid to determine the lowest number of moves required to get the cube from any given muddled configuration to the color-aligned solution.
“Every solver of the Cube uses an algorithm, which is a sequence of steps for solving the Cube,” said the team of mathematicians, who include Morley Davidson of Ohio’s Kent State University, Google engineer John Dethridge, German math teacher Herbert Kociemba and Tomas Rokicki, a California programmer.
“There are many different algorithms, varying in complexity and number of moves required, but those that can be memorized by a mortal typically require more than forty moves.”
“One may suppose God would use a much more efficient algorithm, one that always uses the shortest sequence of moves; this is known as God’s Algorithm. The number of moves this algorithm would take in the worst case is called God’s Number. At long last, God’s Number has been shown to be 20.”
The research, published online, ends a 30-year search for the most efficient way to correctly align the 26 colored cubes that make up Erno Rubrik’s 1974 invention.
Continues at Discovery News …