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Domain: cube20.org

Stories and comments across the archive that link to cube20.org.

Comments · 6

  1. Re:What does it mean to 'solve a rubiks cube'? by ShanghaiBill · · Score: 5, Informative · on Robot Solves Rubik's Cube In Less Than a Second (livescience.com)

    Solves -which- permutation of a Rubik's cube in less than a second? Every single one? How can they prove that before the end of the universe?

    It has been proven that 20 moves suffice to solve Rubik's Cube from any starting position.

    If you restrict each move to a quarter turn, then 26 moves suffice.

    The proof only took 35 years of CPU time.

  2. Re:alas ! by The+boojum · · Score: 4, Informative · on Lego Robot Solves Rubik's Cube Puzzle In 3.253 Seconds

    "God's number" is 20.

  3. Re:Which supercomputer? by eulernet · · Score: 2 · on Google Supercomputers Tackle Giant Drug-Interaction Data Crunch

    The fastest supercomputer (http://en.wikipedia.org/wiki/Tianhe-2) runs at 33.86 petaflops, while Boinc currently runs at 8.26 petaflops (http://boincstats.com/en/stats/-1/project/detail).

    3 years ago, Google's computers were used to solve Rubik's cube:
    http://cube20.org/

    We can suppose that combined Google servers are above 33Pflops.

  4. Re:Total Moves Not Moves/second by Kunnis · · Score: 5, Informative · on Android Phone Solves Rubik's Cube In 12.5 Seconds

    The best solution for a rubix cube is always less then 20 moves (see http://www.cube20.org/ ) It averages around 18 moves for the best solution. That's 27 seconds to solve on average. Where this 11 second youtube video shows a guy solving a cube.. in less then 11 seconds. I can do it in about 60 seconds and I'm not very good. Also, before using computerized solutions, you have to know your whole solution. The manual solutions you can figure out as you go along... you can figure out your next steps while you're manipulating your current step.

  5. Re:35 years of computer time by Nukenin · · Score: 1, Informative · on Rubik's Cube Now Solvable in 20 Moves

    How about measuring that in actual computer usage? X MHz on Y cores per Z nodes over A hours? Or at least say it would have taken one X MHz processor 35 years to compute it.

    A simple visit to the web page followed by a modicum of reading would have led you to the following (emphasis added):

    Lots of Computers

    Finally, we were able to distribute the 55,882,296 cosets of H among a large number of computers at Google and complete the computation in just a few weeks. Google does not release information on their computer systems, but it would take a good desktop PC (Intel Nehalem, four-core, 2.8GHz) 1.1 billion seconds, or about 35 CPU years, to perform this calculation. .

  6. Why approximate numbers? by Romario77 · · Score: 3, Insightful · on Rubik's Cube Now Solvable in 20 Moves

    They give the distance and number of positions for the cube here: http://www.cube20.org/ What I don't understand is why they have only approximate number 20 moves - from the article on the link above I understand that they solved all of the 20-moves combinations so they must know the exact number of those combinations