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1Novak
Copied from the BBC on-line newspage today.
Maximum number of face turns needed to solve Rubik cube - "God's number" - is 20. This proof was arrived at in 2010 by team of researchers led by Tomas Rokicki, a programmer from Palo Alto, California.
I must be pretty good, I can use far more than this “Maximum”.
Maximum number of face turns needed to solve Rubik cube - "God's number" - is 20. This proof was arrived at in 2010 by team of researchers led by Tomas Rokicki, a programmer from Palo Alto, California.
I must be pretty good, I can use far more than this “Maximum”.
2thorold
I think that makes sense if you think like a mathematician, but it's been compressed by a journalist from what was probably a clearer original text. The researchers presumably proved that, starting from any arbitrary configuration, if you make the most efficient possible move each time you never need more than 20 moves to solve the puzzle. Of course, that doesn't tell us what the most efficient next move actually is.
4thorold
http://www.cube20.org/
Apparently the term "God's number" comes from the notion that this is the maximum number of moves an omniscient being (who of course has memorised all the optimum solutions) would need to solve the puzzle.
Apparently the term "God's number" comes from the notion that this is the maximum number of moves an omniscient being (who of course has memorised all the optimum solutions) would need to solve the puzzle.
5krazy4katz
Shouldn't it be the minimum number needed to solve…
6jjwilson61
No, because if the cube has been shuffled randomly it may be solved in one, or even zero, moves. It's saying that no matter what the initial state of the cube a perfect player will need at most 20 moves.
7krazy4katz
Ah, the subtleties…
Thank you for the explanation.
Thank you for the explanation.
18thorold
You can, but you have to enter it as an html entity (<): < 20
But the value twenty is also possible, so it should be ≤ 20
But the value twenty is also possible, so it should be ≤ 20
19Novak
So........Instead of all that nonsense of:
Maximum number of face turns needed to solve Rubik cube - "God's number" - is 20.
What they mean is: The number of face turns needed to solve Rubik cube - is (less-than symbol) 20.
The Maximum/Minimum bit just confused everyone. And these are journalists?
>2 thorold: I think that makes sense if you think like a mathematician, but it's been compressed by a journalist......
So.. .. .. The number of turns is compressed to only 15? :)
Maximum number of face turns needed to solve Rubik cube - "God's number" - is 20.
What they mean is: The number of face turns needed to solve Rubik cube - is (less-than symbol) 20.
The Maximum/Minimum bit just confused everyone. And these are journalists?
>2 thorold: I think that makes sense if you think like a mathematician, but it's been compressed by a journalist......
So.. .. .. The number of turns is compressed to only 15? :)
20krazy4katz
I'm outta here...
22krazy4katz
No way. Save yourself! ;-)
23Amtep
Simpler: "The Rubik's cube can be solved in 20 or fewer moves no matter how scrambled it is, and there are some starting positions that require the full 20 moves."
26PhaedraB
>25 Amtep: Good re-frame, thanks!
27Novak
The puzzle, surely, is to work it out for yourself. (I have not yet managed but I'm close.)
The idea of getting a video to learn how to do it is counter-productive.
The idea of getting a video to learn how to do it is counter-productive.
29dtw42
I saw the subject heading for this thread and vainly hoped it might be about crosswords. Hey ho. I'm with PhaedraB on this one: my parents bought me an unbranded knock-off Rubik's cube back in the 80s and I never managed to solve that. Because it wasn't a genuine jobbie I've never been sure whether my lack of success with it was down to my not-very-analytical brain, or it being unsolvable.
30Novak
>29 dtw42: So.. .. .. You reckon the reason you couldn't do it was.. .. because it was a fake? Nice try. :)