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Thread: algs that goes back to solved position after X times

  1. #21
    Member riffz's Avatar
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    Quote Originally Posted by theZcuber View Post
    Explain why R U has a factor of 105 then
    You don't understand what he's trying to say.
    Average of 12/Official: 14.43/15.17 --- BLD PB/Official: 53.31/1:23.18
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    Member Cielo's Avatar
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    Quote Originally Posted by theZcuber View Post
    Explain why R U has a factor of 105 then
    105=3x5x7, each is ≤ 12.

    As for 105, copy from CubeTwister:
    Twists: 3l 6f 12q
    Order: 105v 420r

    Permutation:
    (-ufl,ulb,ubr,bdr,dfr) (+urf)
    (fu,lu,bu,ru,rb,rd,rf)
    (+r) (+u)

    Quote Originally Posted by bwronski View Post
    how long does it take for this one to repeat?
    U L D R
    Twists: 3l 6f 12q
    Order: 315v 1260r

    Permutation:
    (+ufl) (+dlf) (+urf) (+dfr) (+ubr) (+drb,dbl,bul)
    (fu,lf,fd,rf,ru) (dr,db,dl,bl,ul,ub,br)
    (+r) (+d) (+l) (+u)

  3. #23
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    WOW i didn't knew there was actually a term for this things...
    this is neat!
    can someone explain again why 13 is not possible?
    i didn't get that
    come to the dark side(ZZ) we dont have cube rotations!!!
    had SUB20 singe in 7 methods

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    Quote Originally Posted by nitay6669 View Post
    can someone explain again why 13 is not possible?
    i didn't get that
    In short, since 13 is a prime number, you would need to have 13 pieces that can form a 13-cycle. Since the most number of pieces of one type is 12 (and pieces only can be permuted among other pieces of the same type), there are not sufficient pieces to form a 13-cycle. Hence, you can't make a 13-cycle, so no order-13 maneuvers. However, you can get an order-35 position, for instance, since it is possible to make separate cycles of lengths 7 and 5. (LCM (7,5) = 35. LCM means least common multiple.)

  5. #25
    Member Ranzha V. Emodrach's Avatar
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    U L D R takes 315 repetitions.
    R y takes 1260, and ULDR is a rotation of (R y)4. Therefore, 1260/4 = 315.

    I just remembered Joël has an order calculator. Have fun, everybody.
    http://solvethecube.110mb.com/tools.html#order
    Last edited by Ranzha V. Emodrach; 08-23-2011 at 06:22 PM.
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  6. #26
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    Computer cube PB averages of 12: [Clock: 5.72] [Pyraminx: 3.44] [Megaminx: 49.52]
    [2x2: 2.66] [3x3: 8.71] [4x4: 29.06] [5x5: 52.69] [6x6: 1:34.78] [7x7: 2:20.34]

  7. #27
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    does anyone have a odd number of QTM moves that repeaced an odd number of times returns to a solved state?

    (or is this not possible?)
    [01:44] <+aronpm> CPdragon: here have the rest of my bld power.... abracadabra *waves arms about*

  8. #28

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    Quote Originally Posted by Cool Frog View Post
    does anyone have a odd number of QTM moves that repeaced an odd number of times returns to a solved state?

    (or is this not possible?)
    we could simplify this problem by asking, "is there any algorithm with an odd number of QTM moves that returns the cube to its starting position?" Let's assume there is, call such an algorithm X. Then our solution would be (R U X) *105. (if you don't count X repeated once as a solution)

    If there exists no X, then I can confidently state that every legal scramble + solve with no pops on a 3x3x3 cube has an even number of QTM moves.

  9. #29
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    Quote Originally Posted by Cool Frog View Post
    does anyone have a odd number of QTM moves that repeaced an odd number of times returns to a solved state?

    (or is this not possible?)
    It isn't possible. Each turn in QTM changes the permutation parity of the corners (whether the permutation can be solved with 3-cycles or not). So after an odd number of moves in QTM, the permutation parity of the corners is changed. If your question was possible, then there would be some sequence with an odd number of moves QTM which goes from solved to solved, and since that sequence must change the corner permutation parity, this can't be done.
    Computer cube PB averages of 12: [Clock: 5.72] [Pyraminx: 3.44] [Megaminx: 49.52]
    [2x2: 2.66] [3x3: 8.71] [4x4: 29.06] [5x5: 52.69] [6x6: 1:34.78] [7x7: 2:20.34]

  10. #30

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    so therefore all legal pop-less scramble+solves ever done on a 3x3x3 were even QTM. interesting.

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