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Rubiks Cube Solvable in 20 moves, from any state. 
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http://www.cube20.org/

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Every position of Rubik's Cube™ can be solved in twenty moves or less.
With about 35 CPU-years of idle computer time donated by Google, a team of researchers has essentially solved every position of the Rubik's Cube™, and shown that no position requires more than twenty moves.

Every solver of the Cube uses an algorithm, which is a sequence of steps for solving the Cube. One algorithm might use a sequence of moves to solve the top face, then another sequence of moves to position the middle edges, and so on. There are many different algorithms, varying in complexity and number of moves required, but those that can be memorized by a mortal typically require more than forty moves.

One may suppose God would use a much more efficient algorithm, one that always uses the shortest sequence of moves; this is known as God's Algorithm. The number of moves this algorithm would take in the worst case is called God's Number. At long last, God's Number has been shown to be 20.

It took fifteen years after the introduction of the Cube to find the first position that provably requires twenty moves to solve; it is appropriate that fifteen years after that, we prove that twenty moves suffice for all positions.

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Wed Aug 11, 2010 10:55 am
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ProfessorF wrote:
http://www.cube20.org/

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There are many different algorithms, varying in complexity and number of moves required, but those that can be memorized by a mortal typically require more than forty moves.


Could it be 42? the answer to life the universe and everything?

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Wed Aug 11, 2010 11:22 am
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In my world it's not solvable at all...... ever.
I have never been able to finish a Rubiks Cube.
Annoyingly my mate Steve can do them in less than a minute every time.

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Wed Aug 11, 2010 2:35 pm
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l3v1ck wrote:
In my world it's not solvable at all...... ever.
I have never been able to finish a Rubiks Cube.
Annoyingly my mate Steve can do them in less than a minute every time.

I probably could but....

... why?

It's the same as Sudoku and Big Brother for me - not entertaining in the least

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Wed Aug 11, 2010 3:29 pm
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If it's the same algorithm it was developed years ago by a kid....

Someone on my course did a graphical one for their FYP... not sure why it's not like the algorithm was new or anything

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Wed Aug 11, 2010 8:08 pm
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I have been able to solve them within a minute in the past (about a year ago in fact) but if you don't keep doing it you lose the algorithms and forget how to solve it from certain cases.

My record is about 42 seconds ish. (That's using a randomly generated cypher sequence to mix up the cube in the first place).

I wonder if it will ever get moved down to 19?

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Wed Aug 11, 2010 8:19 pm
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Oh, having re-read the OP I can see that they have mathematically proved that at least one starting position requires at least 20 moves.

So 19 isn't going to happen.

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Wed Aug 11, 2010 8:20 pm
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I’ve never been able to do the cube without help from a guide. :(

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Thu Aug 12, 2010 9:57 am
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paulzolo wrote:
I’ve never been able to do the cube without help from a guide. :(

I have never been able to do a Rubiks cube without help from a screwdriver. :oops:

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Thu Aug 12, 2010 2:32 pm
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3 step method

remove one corner cube
take apart cube
put together
finished :lol:

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Thu Aug 12, 2010 2:34 pm
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bobbdobbs wrote:
3 step method

remove one corner cube
take apart cube
put together
finished :lol:


That’s pretty much how I’ve done it in the past.

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Thu Aug 12, 2010 3:42 pm
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bobbdobbs wrote:
3 step method

remove one corner cube
take apart cube
put together
finished :lol:

A slight variation on my solution but that works for me as well.

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Thu Aug 12, 2010 4:09 pm
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