## Rubik's Cube Algorithm Cut Again, Down to 23 Moves 202

Posted
by
timothy

from the at-this-rate-one-will-soon-be-enough dept.

from the at-this-rate-one-will-soon-be-enough dept.

Bryan writes

*"The number of moves necessary to solve an arbitrary Rubik's cube configuration has been cut down to 23 moves, according to an update on Tomas Rokicki's homepage (and here). As reported in March, Rokicki developed a very efficient strategy for studying cube solvability, which he used it to show that 25 moves are sufficient to solve any (solvable) Rubik's cube. Since then, he's upgraded from 8GB of memory and a Q6600 CPU, to the supercomputers at Sony Pictures Imageworks (his latest result was produced during idle-time between productions). Combined with some of Rokicki's earlier work, this new result implies that for any arbitrary cube configuration, a solution exists in either 21, 22, or 23 moves. This is in agreement with informal group-theoretic arguments (see Hofstadter 1996, ch. 14) suggesting that the necessary and sufficient number of moves should be in the low 20s. From the producers of Spiderman 3 and Surf's Up, we bring you: 2 steps closer to God's Algorithm!"*
## Solvable? (Score:5, Interesting)

## Re:18 moves is the limit (Score:3, Interesting)

So there might be actually 4^6 solutions (4096).

## Slightly offtopic (Score:3, Interesting)

So I'm curious if anyone else has experienced this as being the

obviousbut not perfect solution?## Re:Mastermind (Score:1, Interesting)

## Re:Solvable? (Score:1, Interesting)

Soon, there were a whole lot of people crowded around, staring intensely at the cards, trying to find the set. With that many cards, there just

hadto be one. (The 20-card grouping doesn't even look like a stuck board -- it looks in many ways like there should be a set. Even the fact that the number of cards is supposed to be a multiple of 3 didn't really clue anyone in.)## Re:Slightly offtopic (Score:2, Interesting)

As someone who still carries a cube around, I would have to say that you can still be well under a minute with a corners first solution, and not have to memorize as many routines (15-20 tops) as someone using the more efficient Fridrich F2L solution (76 much longer routines minimum) not to mention the additional difficulty of having to locate two cubes at a time for corner-edge pairs. This is, as a task, rather like human computing. Do you stick with a short program that's less error prone, or do you write a more complicated one that hogs more memory in the hope of getting it done a few cycles sooner? I'm surprised at how many so-called 'nerds' on this thread disregard the cube as some sort of frustrating toy that can't be done except by paint or sticker removal (especially when disassembly is more reliable :P) instead of wanting to understand the behavior of groups and physically grasping algorithm efficiency. Cudos to KokorHekks for solving it himself!

## Re:Do the math, quick! (Score:1, Interesting)

(Yes, I know that on average about 1.5 stickers are correct, but that wouldn't fit in with the joke, and no rubik's cube is perfectly random anyway)

## Re:I can always do it.... (Score:1, Interesting)