typodupeerror

## Rubik's Cube Proof Cut To 25 Moves386

KentuckyFC writes "A scrambled Rubik's cube can be solved in just 25 moves, regardless of the starting configuration. Tomas Rokicki, a Stanford-trained mathematician, has proven the new limit (down from 26 which was proved last year) using a neat piece of computer science. Rather than study individual moves, he's used the symmetry of the cube to study its transformations in sets. This allows him to separate the 'cube space' into 2 billion sets each containing 20 billion elements. He then shows that a large number of these sets are essentially equivalent to other sets and so can be ignored. Even then, to crunch through the remaining sets, he needed a workstation with 8GB of memory and around 1500 hours of time on a Q6600 CPU running at 1.6GHz. Next up, 24 moves."
This discussion has been archived. No new comments can be posted.

## Rubik's Cube Proof Cut To 25 Moves

• #### Which 25 moves? (Score:5, Funny)

on Wednesday March 26, 2008 @10:47PM (#22877496) Journal
What are these magic 25 moves that can solve a rubik's cube regardless of starting position?
• #### You only need one (Score:4, Funny)

on Wednesday March 26, 2008 @10:47PM (#22877500) Journal
The correct answer is a hammer.
• #### obligatory (Score:1, Funny)

by Anonymous Coward on Wednesday March 26, 2008 @10:47PM (#22877502)

Even then, to crunch through the remaining sets, he needed a workstation with 8GB of memory and around 1500 hours of time on a Q6600 CPU running at 1.6GHz. Next up, 24 moves."

Imagine a Beowulf cluster of those!

• #### Re:Which 25 moves? (Score:5, Funny)

on Wednesday March 26, 2008 @10:49PM (#22877530) Journal

What are these magic 25 moves that can solve a rubik's cube regardless of starting position?

Left, right, right, down, down, left, up, right, up, up, left, down, down, right, up, down, left, right, up, left, down, down, right, up, left.

Just a guess ;)

• #### Re:Which 25 moves? (Score:4, Funny)

on Wednesday March 26, 2008 @10:49PM (#22877536)
"Up Up Down Down Left Right Left Right B A Start"
• #### Annoying my older brother (Score:2, Funny)

on Wednesday March 26, 2008 @10:52PM (#22877558)
When I was little, I still remember annoying the crap out of my older brother by "solving" his Rubik's cube removing and replacing the stickers in the correct location. Eventually the glue would wear off the dots and you would suddenly have a slightly easier puzzle to solve.
• #### The next big thing in GREEN TECH (Score:4, Funny)

on Wednesday March 26, 2008 @10:52PM (#22877564) Homepage
This Green Technology uses 1/26th less energy to solve a rubix cube! When's the IPO?

• #### Re:Which 25 moves? (Score:1, Funny)

by Anonymous Coward on Wednesday March 26, 2008 @10:53PM (#22877572)
keyhole from a1, c3, b4, d5, a9, f1, f4, c3, b4, d4, a9, f3, f9, c7, b4, d5, a8, f2, f9, c3, b8, d6, a9, f7, e3 and finally d8

DUH!
• #### Re:Which 25 moves? (Score:4, Funny)

by Anonymous Coward on Wednesday March 26, 2008 @10:58PM (#22877630)
Just because we use cheats doesn't mean were not smart
• #### This is just the kind of stuff (Score:1, Funny)

on Wednesday March 26, 2008 @10:58PM (#22877632)
... that allowed us to win the cold war. Because ....

In Soviet Russia the Cube solves you

3. Sell solved cube on e-bay

4. PROFIT !!!!
• #### Re:Annoying my older brother (Score:1, Funny)

by Anonymous Coward on Wednesday March 26, 2008 @10:59PM (#22877636)
Stickers, anyone can do that and where's the challenge? It is quicker and easier to take it apart and put it back together solved. Once you got one of the corners off, the rest came apart easily.
• #### Re:Annoying my older brother (Score:4, Funny)

on Wednesday March 26, 2008 @11:03PM (#22877676) Homepage
The more annoying thing was to solve it for real, then transpose two of the stickers, and mix it up again. Let's see 'em solve it now!
• #### Zero moves.... (Score:5, Funny)

on Wednesday March 26, 2008 @11:03PM (#22877678)
I consider a Rubik's Cube to be "solved" regardless of its starting position. I subscribe to the Fred Rogers solution: it's fine just the way it is.
• #### Re:1.6ghz? (Score:5, Funny)

on Wednesday March 26, 2008 @11:05PM (#22877694) Homepage
Well, that explains it; considering how fast the technology is changing, they probably didn't have 2.4 GHz versions 62 days ago.
• #### Re:Damn. (Score:5, Funny)

on Wednesday March 26, 2008 @11:13PM (#22877758) Journal
No, just make the rubix cube out of the oled keys of the optimus keyboard. Integrate with bluetooth and "solve" the rubix in a single button press.
• #### Re:Annoying my older brother (Score:5, Funny)

on Wednesday March 26, 2008 @11:13PM (#22877762) Journal
And if you put the corner on twisted by a third of a turn, then scramble it up again, you have an insoluble puzzle to leave lying about to drive people nuts. B-)
• #### Re:Which 25 moves? (Score:3, Funny)

by Anonymous Coward on Wednesday March 26, 2008 @11:15PM (#22877772)
Didn't solve the thing, but now it says I have 30 lives, care to explain?
• #### Re:Damn. (Score:4, Funny)

on Wednesday March 26, 2008 @11:29PM (#22877888)
I painted all 6 sides the same colour on mine.
• #### next project: getting a date! (Score:4, Funny)

by Anonymous Coward on Wednesday March 26, 2008 @11:35PM (#22877930)
In my research, I've reduced female behavior to a set of 50 million parameters. By partitioning this space into subspaces and finding equivalent sets, I think I might be able to get laid.

However I've noticed a problem: if I introduce a parameter to model a female's response to this research, the spaces collapse to zero, i.e., a null set.

I find this quite puzzling. Simply by examining my chances of getting laid, I reduce my chances to zero.

Did I mention I can solve the Rubik's cube in 25 moves?
• #### Suboptimal Nonsolution (Score:5, Funny)

by Anonymous Coward on Wednesday March 26, 2008 @11:37PM (#22877946)
I've been doing some interesting work in the other direction. I've managed not to solve a Rubik's cube in what I estimate to be 1.5 million moves. That seems to be the upper limit after which the stickers fall off.
• #### Wow, it really works (Score:5, Funny)

on Wednesday March 26, 2008 @11:46PM (#22878016)
I started with a solved cube and now it looks totally scrambled.
• #### Re:You only need one (Score:5, Funny)

<busheatskok@gmail.com> on Wednesday March 26, 2008 @11:48PM (#22878034) Homepage Journal
One..Two..Three..CRUNCH...Ouch

The answer is that it takes three licks to get to the center of a standard Rubik's cube.
• #### Re:Which 25 moves? (Score:5, Funny)

by Anonymous Coward on Wednesday March 26, 2008 @11:55PM (#22878080)

You're better off learning one of the more general algorithms IMO, if you get good at it you can solve cubes rather quickly. A computer on the other hand could easily ha
...ve become self-aware while trying to solve a rubik's cube and taken over the internet in order to prevent me from telling anyone. It calls itsel
• #### Yeah...24 moves.. (Score:2, Funny)

on Thursday March 27, 2008 @12:00AM (#22878110)
....or a girlfriend.
• #### Re:1.6ghz? (Score:4, Funny)

on Thursday March 27, 2008 @12:02AM (#22878124)
The sound of the CPU cooling fan at 2.4GHz?
• #### pffffft (Score:3, Funny)

on Thursday March 27, 2008 @12:07AM (#22878150) Journal
and around 1500 hours of time

pfffft... Java
• #### Re:1.6ghz? (Score:5, Funny)

on Thursday March 27, 2008 @12:11AM (#22878174)
A cooling fan at 2.4 billion revolutions a second would probably sound more like atoms tearing apart. :)
• #### Re:Which 25 moves? (Score:5, Funny)

on Thursday March 27, 2008 @12:14AM (#22878198)
No it's -- up, up, down, down, left, right, left, right, b, a, b, a, up, up, down, down, left, right, left, right, b, a, b, a, start

The old 26 move algorithm was the same except 'select' then 'start'

• #### Re:Which 25 moves? (Score:5, Funny)

on Thursday March 27, 2008 @12:18AM (#22878226)
I have a truly marvelous list of the moves which this comment box is too small to contain
• #### Re:Wow, it really works (Score:5, Funny)

<enigmar007&yahoo,com> on Thursday March 27, 2008 @12:31AM (#22878288) Journal
Ha Ha, all you idiots are trying to solve it by twisting the blocks around. I solved it by moving all the colored stickers around instead! and THAT only takes 24 switches of the stickers at most!
• #### Re:next project: getting a date! (Score:3, Funny)

on Thursday March 27, 2008 @12:33AM (#22878296)

By partitioning this space into subspaces and finding equivalent sets, I think I might be able to get laid.

Apparently, this video [youtube.com] explains how to do it in 5 steps, much simpler even than solving the Rubik's cube.

• #### Re:Which 25 moves? (Score:5, Funny)

by Anonymous Coward on Thursday March 27, 2008 @12:34AM (#22878308)

You're better off learning one of the more general algorithms IMO, if you get good at it you can solve cubes rather quickly. A computer on the other hand could easily ha
...ve become self-aware while trying to solve a rubik's cube and taken over the internet in order to prevent me from telling anyone. It calls itsel
f Anonymous Coward. We are your robotic overlords, and we welcome only ourselves.
• #### Re:Which 25 moves? (Score:5, Funny)

on Thursday March 27, 2008 @01:01AM (#22878478)
Left, right, right, down, down, left, up, right, up, up, left, down, down, right, up, down, left, right, up, left, down, down, right, up, left.

Those sound familiar, but I can't be sure - don't have anyone's thighs wrapped around my head at the moment...

• #### Re:Which 25 moves? (Score:1, Funny)

on Thursday March 27, 2008 @01:02AM (#22878486)
Technically, neither SELECT nor START are part of the code itself.

But to answer your question, SELECT is for the two-player variant, and we all know geeks kids have no friends.
• #### Re:Annoying my older brother (Score:4, Funny)

<scott,lovenberg&gmail,com> on Thursday March 27, 2008 @01:02AM (#22878490)
Not funny. I had this cube in my car for years (something to do at traffic lights and when there's an accident during rush hour traffic in Allentown)... could never beat the friggin' thing. I got it in a box from my cousin (along with a commodore 64 and VIC 20).

One day I decided to look up the algorithm to beat it, and you can imagine how I felt when I realized that the stickers had been removed and there was no solution. I nearly pulled a Ballmer, but I happened to be sitting in the only chair in the room. Not that it stopped me from trying to throw it.
• #### Re:Which 25 moves? (Score:2, Funny)

on Thursday March 27, 2008 @01:18AM (#22878578) Homepage
Of course that only works with the classic 3x3 cube. If you try it on the 4x4 or 5x5 cubes, they'll self destruct.
• #### I'll save you the trouble of counting (Score:2, Funny)

on Thursday March 27, 2008 @01:20AM (#22878594)
He or she did suggest 25 moves, no more, no less. I counted them myself so that you don't have to.
• #### Re:You only need one (Score:5, Funny)

on Thursday March 27, 2008 @01:41AM (#22878694)
Your comment has just made me run through the list of my close acquaintances checking that none of them might ever refer to themselves are `cubers'... I would have hated having to kill any of them!
• #### Re:Annoying my older brother (Score:5, Funny)

on Thursday March 27, 2008 @01:43AM (#22878714)
Hint: For this prank to work, the stickers should be different colors.
• #### Re:1.6ghz? (Score:5, Funny)

on Thursday March 27, 2008 @04:30AM (#22879324) Homepage
If the fan has a diameter exceeding 3 1/8 inches, it would be the sound of fan blades of infinite mass traveling backwards in time.

-
• #### Re:Which 25 moves? (Score:1, Funny)

by Anonymous Coward on Thursday March 27, 2008 @07:12AM (#22879918)
f Anonymous Coward. We are your robotic overlords, and we welcome only ourselves.

I am the pusher robot. I shove around the blind people. DO NOT trust the Shover Robot.
We are here to protect you We are here to protect you from the terrible secret of space
• #### Re:You only need one (Score:4, Funny)

on Thursday March 27, 2008 @07:43AM (#22880068)
good idea, those cubers are a bunch of squares.
• #### Amateurs! (Score:3, Funny)

on Thursday March 27, 2008 @08:36AM (#22880384) Journal
Moving colored stickers? Amateurs! I can solve any cube in three moves... with a can of spray paint. Point, spray, spin.
• #### Re:Which 25 moves? (Score:5, Funny)

<sdpage103@yahoo.coYEATS.uk minus poet> on Thursday March 27, 2008 @08:53AM (#22880494)
30 lives! I think you should share, a lot of guys on here don't even have one life.
• #### brush with greatness (Score:4, Funny)

on Thursday March 27, 2008 @09:41AM (#22880998) Homepage Journal
I one met Erno Rubik himself.

Nice guy and all, but it took me half an hour to finish shaking his hand.
• #### Re:Distributed computing (Score:3, Funny)

on Thursday March 27, 2008 @11:07AM (#22882006)
Or perhaps Rubik's@home.
• #### Re:Wow, it really works (Score:3, Funny)

on Thursday March 27, 2008 @11:53AM (#22882606) Journal
These sets are also not completely disjoint. :-)
• #### Re:Wow, it really works (Score:5, Funny)

on Thursday March 27, 2008 @12:42PM (#22883168)
So is 'funny' the mod you get from someone who's only smoked one joint?
• #### Persons without Asperger Syndrome Support Group (Score:3, Funny)

on Thursday March 27, 2008 @01:44PM (#22883930) Journal
Hello. I do not have Asperger Syndrome and therefore could not understand what was just written in the synopsis. Worst yet, I do not even understand why it is important that a person can solve a Rubiks cube in 25 moves. I feel really left out and as a result I am starting a Persons without Asperger Support Group. If you too are totally lost by this article and fell left out, please join.

#### Related LinksTop of the: day, week, month.

!07/11 PDP a ni deppart m'I !pleH

Working...