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> Mathematicians vied to find the shortest method of unscrambling, which became known as God's algorithm. There's speculation that an all-knowing being could r
by danielvf 9y ago
> Mathematicians vied to find the shortest method of unscrambling, which became known as God's algorithm. There's speculation that an all-knowing being could restore any Cube in 22 moves, but the shortest method discovered so far requires 52. It was found by a British mathematician named Morwen B. Thistlewaite.
In 2010 it was finally proven that 20 moves is enough to solve any possible Rubik's cube ordering, and that it can be no lower.
- passivepinetree 9y agoThat's super interesting. Do you have a source?
- schmich 9y agoGod's number is 20: http://www.cube20.org/ http://www.cube20.org/ They pruned a bunch and then did brute force evaluation of the remaining "hard" positions. It seems strange that there hasn't been a more elegant approach to proving this. An interesting (if obvious) corollary to this result is that the maximum moves between any two Rubik's configurations is 20. The relevant HN thread at that time: https://news.ycombinator.com/item?id=1587340 https://news.ycombinator.com/item?id=1587340
- passivepinetree 9y agoYou're the best. Thank you!
- rurban 9y agoIn combinatorics counting is always the best strategy. People are usually not good in counting, computers are better fit. So no surprise.
- TrunkleBob 9y agoThe page from the team that completed the proof: http://www.cube20.org/ http://www.cube20.org/
- DSMan195276 9y agohttp://www.cube20.org/ http://www.cube20.org/