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Rubik's Cube Proof Cut To 25 Moves

Posted by samzenpus on from the too-much-time-on-your-hands dept.

KentuckyFC writes "A scrambled Rubik's cube can be solved in just 25 moves, regardless of the starting configuration. Tomas Rokicki, a Stanford-trained mathematician, has proven the new limit (down from 26 which was proved last year) using a neat piece of computer science. Rather than study individual moves, he's used the symmetry of the cube to study its transformations in sets. This allows him to separate the 'cube space' into 2 billion sets each containing 20 billion elements. He then shows that a large number of these sets are essentially equivalent to other sets and so can be ignored. Even then, to crunch through the remaining sets, he needed a workstation with 8GB of memory and around 1500 hours of time on a Q6600 CPU running at 1.6GHz. Next up, 24 moves."

9 of 386 comments (clear)

  1. change the game by russellh · · Score: 0, Redundant

    Someone should tell these people it's cheaper to take the cube apart and reassemble it correctly.

    --
    must... stay... awake...
    1. Re:change the game by vonmeth · · Score: 0, Redundant

      It is even easier to take the stickers off and place them correctly.

  2. Re:1.6ghz? by RabidJackal · · Score: 0, Redundant

    ...What? The Q6600 has been out since Jan 2007, and its default speed is 2.4ghz..

  3. Q6600 by SlightOverdose · · Score: 0, Redundant

    I'm going to contribute nothing to this conversation other than to be a nazi and point out that the q6600 CPU runs at 2.4ghz, not the 1.6ghz listed in the article

    http://techgage.com/article/intel_core_2_quad_q6600/

  4. Re:Which 25 moves? by inKubus · · Score: 0, Redundant

    I thought you were going to say Up Up Down Down Left Right Left Right B A B A Select Start

    --
    Cool! Amazing Toys.
  5. Re:Which 25 moves? by sorak · · Score: 0, Redundant

    What are these magic 25 moves that can solve a rubik's cube regardless of starting position?

    Left, right, right, down, down, left, up, right, up, up, left, down, down, right, up, down, left, right, up, left, down, down, right, up, left.


    Just a guess ;)

    Or Up, up, down, down, left, right, left, right, b, a, start


  6. Re:Which 25 moves? by Chonnawonga · · Score: 0, Redundant

    No, no! It's up, up, down, down, left, right, left, right, a, b, select, start. Of course, that just buys you more free moves.

  7. Is this REALLY Slashdot? by Frigid+Monkey · · Score: 0, Redundant

    How very strange that on slashdot of all places no one noticed the article:

    "Even then, to crunch through the remaining sets, he needed a workstation with 8GB of memory and around 1500 hours of time on a Q6600 CPU running at 1.6GHz."

    So they had to underclock this thing to get in phase resonance with the cube or what?

    The Intel Q6600 is a nice little number that runs a 2.4Ghz out of the box.

    --
    "It's all just meme meme around here"
  8. Q6600 at 1.6? by DJRikki · · Score: 0, Redundant

    "8GB of memory and around 1500 hours of time on a Q6600 CPU running at 1.6GHz." - Should have clocked it to 3.0GHz like most other folks :D