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6522Working on learning a 3-look LL

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  • jasmine_ellen
    Sep 5, 2003
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      What a very detailed reply Ryan!

      Here's where I'm up to at the moment... I've learnt several LL edge
      algs -- ones that mess with the corners (which doesn't matter if LL
      edges are oriented first). I already knew several LL edge algs that
      preserve the corners -- I guess these are useful if the corners are
      already done when you get to the LL.

      I already know the Sune and its mirror (can't imagine there'd be any
      cuber who doesn't know this alg?!). I've learnt the algs for the
      three LL corner orientation positions where 2 are corrent and 2
      require twisting. Still need to learn the 2 algs for when all 4
      require twisting.

      I'm aiming to learn the 13 PLL if my enthusiasm lasts that long. In
      case it doesn't, I planned the order that I would learn the algs.
      First I revised the algs that just move the edges since. I knew U and
      H, but for some reason was a bit iffy with Z. After that, I just
      ranked them by 'probability of occurrence'. So, of the remaining 10,
      I've memorised the algs with a frequency of 1/9 or greater (A, R, J,
      G). So, 7 down, 6 more to go.

      I think I need to take a break from new algs and spend some time
      getting the newly memorised algs firmly planted in my head. I'm
      finding that I can remember them without a problem, but I'm still
      taking a bit of time recognising the patterns. I'm not concerned
      though because I know that practise will fix this!

      Jasmine.

      --- In speedsolvingrubikscube@yahoogroups.com, Ryan Heise
      <rheise@p...> wrote:
      > On Mon, Sep 01, 2003 at 11:48:01AM -0000, jasmine_ellen wrote:
      > > I remembered that DanK had something like this on his site about
      a
      > > beginner method, an intermediate method and an advanced method.
      This
      > > is actually what I was after. Who else has something like this on
      > > their site?
      >
      > I'll describe the beginner and intermediate methods that I once
      used.
      > They are simplications of the Fridrich last layer system. You need
      to
      > first understand how that system works:
      >
      > http://www.ws.binghamton.edu/fridrich/system.html#last
      >
      > This general strategy, orienting first, then permuting, is good
      because
      > it is very easy to recognise the positions quickly. But instead of
      > orienting all the pieces at once, you just orient the edges first,
      and
      > the corners second.
      >
      > BEGINNER METHOD
      >
      > First, orient the 4 edges (ie. make a cross). There are only 4
      patterns,
      > and one algorithm to solve them all! To view this, you need to use a
      > fixed width font:
      >
      > --- --- -x- -x-
      > -x- xxx xx- xxx
      > --- --- --- -x-
      >
      > For each pattern, apply the algorithm "R'U'F'U F R" and it will
      take you
      > to the next pattern. Eventually you will end up with a cross.
      >
      > Improvement: notice that if you apply the algorithm when you already
      > have the cross, you will end up with a line. That means that you can
      > jump immediately from the 2nd pattern to the 4th pattern by
      applying the
      > algorithm backwards! So, this step should take an average of 6
      moves.
      >
      > Next, orient the corners. There are only 6 patterns apart from
      solved.
      > Look through this complete list, and find all the patterns (and
      > algorithms) that have a cross already formed:
      >
      > http://www.ws.binghamton.edu/fridrich/Mike/orient.html
      >
      > For the case when 3 corners need to be twisted, I recommend the
      Sune TM
      > algorithm from Petrus. See the applet at the top/right of his page:
      >
      > http://lar5.com/cube/fas6.html
      >
      > I think it's useful to learn to twist them forwards and backwards:
      >
      > - R U R'U R U2 R'
      > - R'U'R U'R'U2 R
      >
      > To see that done fast, have a look at the quicktime movies at the
      bottom
      > of this page:
      >
      > http://lar5.com/cube/speed.html
      >
      > I recommend this algorithm because one of the other orientation
      cases
      > can be solved by just applying this algorithm twice. To know which
      case
      > I'm talking about, apply this to a solved cube: RU2R'U'RUR'U'RU'R'.
      >
      > Now, apply the sune (RUR'URU2R') twice:
      >
      > RUR'URU2R' + RUR'URU2R'
      >
      > Notice that the moves in the middle cancel out? So you can actually
      do:
      >
      > RUR'URU'R'URU2R'
      >
      > which is an "optimal" solution.
      >
      > Next, permute the corners (yes, before the edges). Most of the time
      > there will be a 3 cycle of corners. In this case, look at the 4
      sides of
      > the last layer. On one of the sides, the two last layer corners
      will be
      > matching in colour. Hold those two corners on the back side and do:
      >
      > R'FR' B2 RF'R' B2 R2
      >
      > Now the corners should be solved. If you don't find any two corners
      that
      > match, apply the above algorithm and that should result in a
      position
      > where two corners match. Don't worry, this case rarely happens. If
      you
      > want, you can learn a special algorithm for that case by picking the
      > most attractive one from:
      >
      > http://www.ws.binghamton.edu/fridrich/Mike/permute.html
      >
      > The "Y" pattern on that page has the desired corner effect.
      >
      > Next, permute the edges. Again, most of the time, there will be a 3
      > cycle of edges. You need to learn to cycle the edges forwards and
      > backwards:
      >
      > - R2U FB'R2F'BU R2
      > - R2U'FB'R2F'BU'R2
      >
      > Sometimes, all 4 edges need to be swapped in opposite pairs. That's
      an
      > easy case, so why not learn it:
      >
      > RLU2R'L' [U] R'L'U2RL
      >
      > The [U] means rotate the whole cube from the up side, 90 degrees.
      >
      > There's also a rare case where all 4 edges need to be swapped in
      > adjacent pairs. The algorithm's difficult so it's not worth
      learning.
      >
      > INTERMEDIATE METHOD
      >
      > First, orient everything like the beginner method. Then permute
      > everything like the full blown Fridrich method.
      >
      > How can you learn all the permutations? See my previous email:
      >
      > c
      >
      > There, I list which algorithms to learn first, and which algorithms
      to
      > learn last.
      >
      > ADVANCED METHOD
      >
      > You already know enough! It is not necessary to learn 40 orientation
      > algorithms. 6 is enough. Gilles Roux proved that it is possible to
      > achieve sub-20 times with just these 6 orientation algorithms and 13
      > permutation algorithms. He used the petrus method for the first two
      > layers which gives you a cross automatically when you get to the
      last
      > layer. Using that strategy, those extra orientation algorithms are
      not
      > needed.
      >
      > Ryan
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