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[Speed cubing group] Re: Why slice turns are counted as 2 turns in official comp

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  • Gilles Roux
    ... The main reason for this is as you described below, it feels slower and more cumbersome than a standard face turn, and for speedsolving purposes it is
    Message 1 of 4 , Nov 4, 2004
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      --- In speedsolvingrubikscube@yahoogroups.com, "Dan Harris"
      <dan_j_harris@n...> wrote:

      > [...]
      > Yes, my mind is split too... and it always has been :(
      >
      > I have been an advocate of slice turns = 2 moves, as you well know.
      The main reason for this is as you described below, it feels slower
      and more cumbersome than a standard face turn, and for speedsolving
      purposes it is definitely worse off (at least for my speedsolving...
      Gilles?)
      > [...]


      As I was saying to someone else recently, the one and only metric
      regarding speedcubing is the timer.
      Of course, sequences like E2S2M2E2S2M2 are VERY slow. But M/M' often
      are much faster than a half turn of any face (M'UM'UM'U faster than
      10moves/sec if you count M' as two moves).

      You know that there are many criteria that make moves faster than
      others, that's why people spend their time trying to optimize
      sequences for their hands. For example, the minimization of cube
      reorientations is very important, even if they don't appear in many
      written "algorithms" (it's normal, because different people may
      execute the same sequence differently).

      I could go on for ages talking about what a "speed metric" should
      include. My idea is that people shouldn't think about all of these
      points when considering a metric for a FMC.

      Forget speed. Forget some computer programs too, for them it's more
      efficient to work with fixed centers and half turns.

      Take a 1x1x1 cake. Divide it into three equal parts, three times
      (following the three orthogonal planes). The inner slices are as good
      as the others. I remember when I first saw the cube, it was not a
      bunch of corners and edges, it was just a perfect 3x3x3 matrix and you
      could move any row or column magically.

      Sure you can solve the cube without moving M, S or E, but you can
      solve it with DLB fixed, without moving D, L or F too.

      I see slice moves as normal moves (as I do with bigger cubes), and
      I've yet to read a valid point that could make me change my mind about
      it (yes, I'm an open-minded guy ;-) ).

      I understand why people have problem considering the cube my way. It's
      a matter of how they look at it. If they solve the cube 100 times a
      day thinking with sides only, thinking with slices seems weird. And
      there's the dexterity thing of course. But it's a bit sad because, for
      example, you can't see how simple many commutators based on slices can
      be, and they're not only useful in corners-first methods. It's like
      speaking using a reduced vocabulary.

      Slice moves may appear as complex moves because of the mechanics
      inside the cube (6 axes - but a 3x3x3 could have been built around a
      sphere). I consider them as physically and mathematically simple (it's
      not like considering a RU'R'U fingertrick as a basic move, even if
      complex sequences can improve your "vocabulary").


      There's another subject: Half-turn or quarter-turn metric?

      I think there are three reasons for people to use an half-turn metric:
      - Formulae are shorter and simpler to write.
      - It's actually easy to think with half-turns.
      - You just have to turn your hand a bit more.

      My opinion is that R2 is clearly made of two R (or R') basic moves.
      You can think with half-turns just as you can think with RU'R'U
      sequences, but they're not physically simple.


      This is just a personal point of view of course, I don't write
      official rules.
      HTM is the worst metric you can imagine for a FMC (remember SQTM?),
      but I'll still try to attend CubeStation's competitions :-)


      Gilles.


      PS#1: By the way, there's no limit on the number of competitors for
      CubeStation's challenges. Come with us!

      PS#2: 3x3x3 scrambles could include slices too ;-)

      PS#3: Notation is not really important to me, as long as we can
      understand each others, but I agree that M/E/S is a bit confusing, and
      I don't see why slices would require such specific names.

      PS#4: Mister Kociemba, could you please write a....
    • d_j_salvia
      Hi Dan H, Gilles, Stefan, Josef, Like Gilles I consider each of the three layers equal to the others, since R r L rotates the whole cube (QR). (I use the
      Message 2 of 4 , Nov 4, 2004
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        Hi Dan H, Gilles, Stefan, Josef,

        Like Gilles I consider each of the three layers equal to the
        others, since R r L' rotates the whole cube (QR). (I use the lower
        case letter for slice moves).

        I think the difficulty comes from technique. Take the sequence r U r
        U r U r U which flips over four edges. With a good technique this can
        easily be done as quickly as R U R' U' done twice. I think that if
        someone is not used to slice moves it's much the same as someone not
        being used to doing any finger tricks.

        Regards,

        David J


        --- In speedsolvingrubikscube@yahoogroups.com, "Dan Harris"
        <dan_j_harris@n...> wrote:
        > Yes, my mind is split too... and it always has been :(
        >
        > I have been an advocate of slice turns = 2 moves, as you well know.
        The main reason for this is as you described below, it feels slower
        and more cumbersome than a standard face turn, and for speedsolving
        purposes it is definitely worse off (at least for my speedsolving...
        Gilles?)
        >
        > When the FMC was born, I was not an FM solver, but of course I see
        different now. But after 60 or more competitions spanning 1 and a half
        years, I am reluctant to change things now. And anyway, slice turns
        have their own rank (just not the main one :) ).
        >
        > Maybe the most important people (the FMC experts) will change my
        mind, especially after reading Josef's post, but I seem to remember we
        had a big discussion on the FMC forum a while back, before EC2004, and
        it was still inconclusive.
        >
        > DanH :)
        > ----- Original Message -----
        > From: Stefan Pochmann
        > To: speedsolvingrubikscube@yahoogroups.com
        > Sent: Wednesday, November 03, 2004 11:15 PM
        > Subject: [Speed cubing group] Re: Why slice turns are counted as 2
        turns in official competitions?
        >
        >
        >
        > Wow! You just changed my mind. Well, actually you *split* my mind ;-)
        >
        > So far I've always voted for counting it as 2 turns. That's because
        > when I solve the cube it "feels" slower than a face turn and so I
        > wanted to "punish" it. Now I realize that we should take the
        *purpose*
        > into account. And I vote:
        >
        > - 2 turns. For speedsolving purposes, for example to automatically
        > choose among different algs (e.g. computed by ACube). Here I'm
        > interested in fast execution and slice turns do feel slower generally.
        >
        > - 1 turn. For fewest moves solving purposes. Here execution speed
        > doesn't matter and so for this purpose I agree counting it as 1 feels
        > more natural.
        >
        > Thanks for making me (us?) aware of the difference.
        >
        > Cheers!
        > Stefan
        >
        >
        > --- In speedsolvingrubikscube@yahoogroups.com, "Josef Jelinek"
        > <gloom@e...> wrote:
        > >
        > > Hi,
        > >
        > > the only answer to the question in the subject of this message that
        > > makes sense to me is:
        > > disqualifying competitors using corners-first method
        > > (or its variation), because most people use Fridrich/Petrus
        > > based solution anyway...
        > >
        > > Sure, the slice turns can be slower to perform for most people,
        > > but it is really unimportant for FMC as well as not using
        > > non-optimal UR group sequences that may be better for speedcubing.
        > >
        > > Do slice moves really mean any advantage? Do they move more
        > > pieces in more suitable way, or less pieces to perform permutations
        > > better?
        > >
        > > I have to say that in my opinion the answer is 'no'.
        > > If we analyze face turn:
        > > the number of pieces moved (wrt. the rest of cube) 4 ed. + 4 corn.
        > > the number of facelets moved (depends) max. 4x2+4x3
        > > For the slice turn:
        > > the number of pieces moved (wrt. the rest of cube,
        > > although not compact) 4 edges + 4 centers
        > > the number of facelets moved max. 4 + 4x2
        > >
        > > The only difference is that for slice turns center pieces are
        > > moved instead of corner ones.
        > >
        > > The official rule set up to count slices as 2 turns only puts
        > > some cubers to a position that they cannot compete...
        > > Even though I would use only about 5-7 slice turns in an FMC try
        > > it is such a big handicap that it is not worth participating...
        > >
        > > What do other think? In replies to the "Boost message mail"
        > > it looked that more people are positive to count slices as one turn.
        > >
        > > Josef
      • Chris Sz...
        I am also split on whether to count slices as one or two moves. My logic for it counting as 2 is because a slice actually rotates the internal kernel and 2
        Message 3 of 4 , Nov 4, 2004
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          I am also split on whether to count slices as one or two moves. My
          logic for it counting as 2 is because a slice actually rotates the
          internal kernel and 2 center pieces so in effect it is 2 moves plus
          a cube rotation when looked at mechanically. A normal move would be
          accomplished by rotating 1 center piece(and the 8 pieces around it
          of course)while the kernel remains stationary. But like Gilles said,
          the cube could be built around a sphere where the kernel would not
          be rotated in a slice. For speedcubing purposes though, if I perform
          the slice as 2 moves(danK Z perm), I count it as 2. If I do the
          slice as 1 move(as in L'BLS'L'B'S (I like that alg)), I count it as
          1. For fewest moves, I would be inclined to count it as 1 move, but
          I'm not an expert in that field.

          --barefoot Chris
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