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**rom1****Guest**

Hello everybody,

A collegue of mine asked me an interesting question : is there any identity algorithm for the Rubik's cube (an algorithm that does not change the cube) that is composed of an odd number of movements ?

I call a movement any quarter of turn (L, L', R, R', U, U', D, D', F, F' B, B').

I have some identity algorithm examples :

RR' -> 2 moves

R2 R2 = RR RR -> 4 moves

(R2U)*30 -> 90 moves

(RU')*63 -> 126 moves

(RU)*105 -> 210 moves

I do not think so, but it will be fun trying to prove that. Thanks for sharing the problem.

What is your favorite color?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'Humanity is still kept intact. It remains within.' -Alokananda

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**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,522

There isn't such an algorithm.

Consider the corners of the cube:

After each move, some of the odd labeled corners go into places of even labeled corners and vice versa. So, after any odd number of moves, odd corners end up in even numbered places and the even corners end up in odd numbered places, so such an algorithm is not possible.

Here lies the reader who will never open this book. He is forever dead.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

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Brilliant!

Now, what did you use to draw that cube?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'Humanity is still kept intact. It remains within.' -Alokananda

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**rom1****Member**- Registered: 2014-07-22
- Posts: 1

Ok, simple and efficient, thank you anonimnystefy!

Agnishom wrote:

What is your favorite color?

It's a bluish-yellow

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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,531

That is an impossible color.

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,388

I think they call it green.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,531

Not blue and yellow in equal proportions.

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,388

I never thought about mixing it in equal proportions.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

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ShivamS wrote:

Not blue and yellow in equal proportions.

In what proportions then?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'Humanity is still kept intact. It remains within.' -Alokananda

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,388

I used to mix a can of blue with a can of yellow and always got 2 cans of green.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

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**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,522

Agnishom wrote:

Brilliant!

Now, what did you use to draw that cube?

Found it on the interwebs.

*Last edited by anonimnystefy (2014-07-22 05:14:10)*

Here lies the reader who will never open this book. He is forever dead.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,388

The Geebra can do it.

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

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**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,522

Yeah, but it was easier to just find a pic on the interblag than to make it in GG or anywhere and upload it on imgur.

Here lies the reader who will never open this book. He is forever dead.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,388

I know, I was talking to Agnishom.

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

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**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,522

Ah, yes, sorry.

Unrelated to the topic, have you gotten around to looking at Elaina's problems yet?

Here lies the reader who will never open this book. He is forever dead.

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,388

Hi;

No I have not and she is back in Florida for 3 weeks so I will not have to. I am currently very busy with Ubuntu.

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

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**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,522

What about Ubuntu?

Here lies the reader who will never open this book. He is forever dead.

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,388

I am switching over to it and any such move is very difficult. I am almost done but almost is not good enough.

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

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**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,522

Having any problems?

Here lies the reader who will never open this book. He is forever dead.

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,388

Multitudes of them. I have an XP mentality and it does not fit in a linux world.

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

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You will have a linux mentality soon. What problems do you have?

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'Humanity is still kept intact. It remains within.' -Alokananda

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,388

I am looking for a application dependent fw. There are many for windows but none it seems for linux.

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

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Why not ask on askubuntu.com?

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'Humanity is still kept intact. It remains within.' -Alokananda

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,388

That is where I was looking as well as a lot of other places.

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

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