# What? Doing a Rubik's cube Behind ur back?



## LaffyTaffyKidd (Sep 5, 2008)

My friend recently just did a rubik's cube behind his back w/o memorizing anything.. Is this possible ?? or do you think that he set the cube up?


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## Swoncen (Sep 5, 2008)

He didn't look at the cube before? How should that be possible.. the same thing as when I say: I'm think of a number between 0 - 99999999999999999999. Gues it..


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## Lucas Garron (Sep 5, 2008)

LaffyTaffyKidd said:


> Is this possible ??


Yes.


LaffyTaffyKidd said:


> do you think that he set the cube up?


Yes.


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## Derrick Eide17 (Sep 6, 2008)

Lucas Garron said:


> LaffyTaffyKidd said:
> 
> 
> > Is this possible ??
> ...



that SOOO made me LOL xD haha


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## DAE_JA_VOO (Sep 6, 2008)

If he did NOT set the cube up, then no, that's impossible (well, not impossible, but the chance is pretty much 1 in 43 quintillion).

Your so-called friend is lying to you.


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## shelley (Sep 6, 2008)

Either he set the cube up to a previously memorized position, or he memorized it without your knowledge.


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## waffle=ijm (Sep 6, 2008)

Derrick Eide17 said:


> Lucas Garron said:
> 
> 
> > LaffyTaffyKidd said:
> ...



MEEE TOOO!!!! 

But as funny as it is. its true. it's possible but only if he set it up


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## rjohnson_8ball (Sep 6, 2008)

shelley said:


> Either he set the cube up to a previously memorized position, or he memorized it without your knowledge.



If he said nothing at all, then he likely pre-planned the solve sequence as a joke. An honest person would not leave a doubt in your mind. He would tell you if it was randomly scrambled or not, and how much he knew about it before he solved it.


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## cmhardw (Sep 6, 2008)

You can do a neat trick similar to this legitimately using some cube math. The center of the cube group has 2 permutations, the identity permutation and the superflip permutation. What this means is that the superflip commutes with every other permutation in the cube group.

What this means is you can do a cool trick. I did this to some of my students where I work and they thought it was really neat. I took a solved cube and set it up into the superflip. I then did 2 turns, like U R or something to that affect. The cube at this point, to the untrained eye, looks scrambled. I then asked them to scramble by 2-3 moves to ensure I had not rigged the cube. I told them that my trick only works "most of the way" and that I can get the cube close but not solve it. The last part I have to do with my eyes. So I, behind my back, executed the superflip and brought the cube back around to where everyone could see it. Now I simply have to undo the (probably) 4-5 moves that were done on the cube and it is solved.

The kids who saw me do this knew that I do blindfolded solving, but they thought it was cool that I could "even do it without memorizing" haha. After that I told them the math behind it (I teach at a math learning center, so I kinda had to) ;-)

Chris


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## Ryanrex116 (Sep 6, 2008)

Swoncen said:


> He didn't look at the cube before? How should that be possible.. the same thing as when I say: I'm think of a number between 0 - 99999999999999999999. Gues it..



I guess 13263534754646926569. I hope i'm right!


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## cubeRemi (Sep 6, 2008)

still if you don't know a thing about blindsolving, you could think he didn't memo it even though he did. someone who is very fast can memo in like 18 to 25 sec...

but probably he did set it up.

BTW, i guesss uuhhm 2305843008139952128

( biggest perfect number under 20 digits... )


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## nitrocan (Sep 6, 2008)

Or he has a gimmicked cube.


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## Rubixcubematt (Sep 6, 2008)

i guess 3.1415926535.....

and yes, i think that he did it so he can undo the moves


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## ImNOTnoob (Sep 6, 2008)

Swoncen said:


> He didn't look at the cube before? How should that be possible.. the same thing as when I say: I'm think of a number between 0 - 99999999999999999999. Gues it..



Ooh! I guess 92732535162783496!


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## Derrick Eide17 (Sep 6, 2008)

cmhardw said:


> You can do a neat trick similar to this legitimately using some cube math. The center of the cube group has 2 permutations, the identity permutation and the superflip permutation. What this means is that the superflip commutes with every other permutation in the cube group.
> 
> What this means is you can do a cool trick. I did this to some of my students where I work and they thought it was really neat. I took a solved cube and set it up into the superflip. I then did 2 turns, like U R or something to that affect. The cube at this point, to the untrained eye, looks scrambled. I then asked them to scramble by 2-3 moves to ensure I had not rigged the cube. I told them that my trick only works "most of the way" and that I can get the cube close but not solve it. The last part I have to do with my eyes. So I, behind my back, executed the superflip and brought the cube back around to where everyone could see it. Now I simply have to undo the (probably) 4-5 moves that were done on the cube and it is solved.
> 
> ...



Hahaha 

Very nice Chris


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## Swoncen (Sep 6, 2008)

DAE_JA_VOO said:


> (well, not impossible, but the chance is pretty much 1 in 43 quintillion).



Just because there are 43 quintillion possible combinations does not mean, that the chance is 1 to 43 quintillion to solve it with a random combination.




> I guess 13263534754646926569. I hope i'm right!


I don't remember anymore but I think you are VERY close


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## Inusagi (Sep 6, 2008)

Swoncen said:


> DAE_JA_VOO said:
> 
> 
> > (well, not impossible, but the chance is pretty much 1 in 43 quintillion).
> ...



You're wrong. The moves he applied to that cube is a solution to only one of those combination. Which means that the chances of doing it right is as many combination a cube has.


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## cubeRemi (Sep 6, 2008)

lets say you make 8 random moves ( L L' stuff does not count ) there is no chance at all that you could have solved one of ALL possible states since the cube could be scrambled in a way that AL LEAST more than 8 moves are necessary. 

so I'm sure the chance of solving a random scrambled cube with random moves is les than 1 in 43 quintillion if you are using less than 20 moves.

Also, if you are using a random number of moves the chance of solving it is less than 1 in 43 quintillion…

so I think Swoncen is right 

Remi


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## Stefan (Sep 6, 2008)

DAE_JA_VOO said:


> Your so-called friend is lying to you.





rjohnson_8ball said:


> An honest person would not leave a doubt in your mind.



He made it obvious, so it's perfectly alright. Would be different if he had pretended to memo for let's say 15 seconds.


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## Ryanrex116 (Sep 6, 2008)

> I guess 13263534754646926569. I hope i'm right!


I don't remember anymore but I think you are VERY close [/QUOTE]

Hooray! Wait, was the guessing question rhetorical?


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## CAT13 (Sep 6, 2008)

how long was execution? because that could give away whether it was fake or real... unless it took a long time. And how fast was he turning?


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## rjohnson_8ball (Sep 6, 2008)

cmhardw said:


> ... I took a solved cube and set it up into the superflip...
> Chris



Chris, is there something easier than ((M' U)*4 x y')*3 for superflip? Also, did you ever get my corrections to your pages? See "Description of Fixes" at http://www.geocities.com/rjohnson_8ball/ along with my corrected OLL and PLL pages.


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## VP7 (Sep 6, 2008)

Superflip: U R2 F B R B2 R U2 L B2 R U' D' R2 F R' L B2 U2 F2


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## shelley (Sep 6, 2008)

VP7 said:


> Superflip: U R2 F B R B2 R U2 L B2 R U' D' R2 F R' L B2 U2 F2



Too long and hard to remember. I just set it up into two six-flips.


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## Lucas Garron (Sep 6, 2008)

cubeRemi said:


> lets say you make 8 random moves ( L L' stuff does not count ) there is no chance at all that you could have solved one of ALL possible states since the cube could be scrambled in a way that AL LEAST more than 8 moves are necessary.


I think you mean ANY, not ALL.



cubeRemi said:


> so I'm sure the chance of solving a random scrambled cube with random moves is les than 1 in 43 quintillion if you are using less than 20 moves.
> 
> Also, if you are using a random number of moves the chance of solving it is less than 1 in 43 quintillion…


False. If you have "random scrambled cube" (with "random moves" or whatever), then doing 1 blind move is as likely to put it into a solved state as any other number of blind moves, even a "random" number.


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## cuBerBruce (Sep 6, 2008)

I agree with Lucas. If you don't have any knowledge about your starting position, and you make eight moves, you still have no knowledge about your ending position.

A random position is highly unlikely to be within 8 moves of being solved. But if you make the assumption that your are certain that it is not within 8 moves of the solved position, then you know something about that position, and the assumption of it being a completely random position is false.

Without that assumption, then you have that there is a small probability that it is within 8 moves of the solved state, and there's a small chance that some chosen 8 moves will solve it. The end result is still a 1 in 43 quintillion chance (approximately, of course) of the ending position being a solved cube.

The Cayley graph for Rubik's (for face turns, let's say) looks exactly the same from any node. Because of that symmetry, you can't pick a set of moves that will tend to favor one position with respect to others.


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## rjohnson_8ball (Sep 11, 2008)

shelley said:


> VP7 said:
> 
> 
> > Superflip: U R2 F B R B2 R U2 L B2 R U' D' R2 F R' L B2 U2 F2
> ...



You mean do (R U R' F)*5 for one six-flip then set up for the 2nd six-flip, then undo? Wouldn't that be 40 twists plus setup moves? Would that be hard to track blindfolded? (I got that six-flip from Macky's BLD page.)

I prefer ((M' U)*4 x y')*3. No setups, easy to perform. It leaves the cube rotated correctly when finished. (I discovered this super flipper 20+ years ago. I don't remember if I found it myself or if I read it in David Singmaster's book.)


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## Erik (Sep 11, 2008)

LOL, it really makes me laugh and cry at the same time to see people are actually discussing this xD


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## Cerberus (Sep 11, 2008)

Swoncen said:


> He didn't look at the cube before? How should that be possible.. the same thing as when I say: I'm think of a number between 0 - 99999999999999999999. Gues it..



The answer has to be 42 because obviously we are all hunting for the answer and make this the great question.

@topic I think he just set it up with a scramble he knew so that it looks really scrambled or it was an easy blind scramble for him which he still knew, so that you if you cube don't see the cube and think, haha it's nearly finished..


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## Inusagi (Sep 13, 2008)

cubeRemi said:


> lets say you make 8 random moves ( L L' stuff does not count ) there is no chance at all that you could have solved one of ALL possible states since the cube could be scrambled in a way that AL LEAST more than 8 moves are necessary.
> 
> so I'm sure the chance of solving a random scrambled cube with random moves is les than 1 in 43 quintillion if you are using less than 20 moves.
> 
> ...



Like Lucas said, I am right...


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## MistArts (Sep 13, 2008)

rjohnson_8ball said:


> shelley said:
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> 
> > VP7 said:
> ...



It's easier to execute than the optimal one. Plus, superflip isn't really need in a blindfold solve.


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## Swordsman Kirby (Sep 21, 2008)

MistArts said:


> rjohnson_8ball said:
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> > shelley said:
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If you do 3OP then it may come in handy when there are 10-12 edges misoriented.


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## MistArts (Sep 21, 2008)

Swordsman Kirby said:


> MistArts said:
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> 
> > rjohnson_8ball said:
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Well, if you use a method that doesn't orient first...


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