Over the holiday period, the arXivblog is running a selection of the most popular posts from 2008
26 March 2008: Rubik’s cube proof cut to 25 moves
Last year, a couple of fellas at Northeastern University with a bit of spare time on their hands proved that any configuration of a Rubik’s cube could be solved in a maximum of 26 moves.
Now Tomas Rokicki, a Stanford-trained mathematician, has gone one better. He’s shown that there are no configurations that can be solved in 26 moves, thereby lowering the limit to 25.