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Date: Mon, 10 Jun 1996 09:17:05 -0700
To: CUBE-LOVERS@ai.mit.edu
From: Lars Petrus
Subject: Re: Speed cubing
> Anyways, I am curious what methods people use. I've asked around and it
>seems
>most people prefer to go top/middle/bottom. In fact, all the published
>solutions go that way. But, I learned to go top/bottom/middle because it is
>MUCH easier. At the same time, I've seen that when solving a single face,
>most solutions suggest doing edge and the corner pieces, but I do corner and
>then edge. I think this has to do with whether you do the middle or the bottom
>next because with the middle/bottom approach you can leave out one corner
>piece to do the middle. But if you do bottom/middle then you can leave out
>an edge piece to aid in getting the buttom edge pieces done.
>
>
> Here is a quick overview of my solution (because it is different than most
>peoples):
>
> 1. do the top face. 4 corners then any 3 edges. (intuitive)
> 2. align bottom corner pieces. (pattern)
> 3. rotate bottom corner pieces so the correct color is showing (pattern)
> 4. place the remaining 4 bottom edges and the missing top edge (intuitive)
> 5. put the 4 middle edge pieces in the correct positions (intuitive)
> 6. rotate edge pieces as needed (pattern)
>
>
> Anyways, is there one technique that almost all speedy solutions use? I've
>tried the top/middle/bottom solutions but they seem very uninuitive.
The layer by layer techniques are useless for speed cubing. Most people
use them, because they are a simple way for the human mind to approach the
problem, but they are not natural "from the cubes point of view".
In the final of the swedish championship, 8 of 11 competitors used the
vanilla layer-by-layer method. The other 3 of us finished 1, 2 and 3!
The basic problem with the layer method is obvious, and very big. When you
have completed the first layer, you can do *nothing* without breaking it up.
So you break it, do something, then restore it, again and again. It's quite
obvious that this layer is in the way of your solution, not a part of it.
My approach was to find something that, once acomplished, did not need to
be broken up. A true step on the way to a solution. What I came up with was
to first solve a 2x2x2 corner. After that, you can move three sides freely,
and not touch what you achieved. Then I expand it to a 2x2x3, which leaves
two sides free. Then you fiddle a bit, and go to 2x3x3 and 3x3x3.
1. do the 2x2x2 (intuitive)
2. expand it to a 2x2x3 (intuitive)
I don't know how to say this in group-babble, but when you move just 2
sides, you can never "truly" rotate an edge or move a corner. This means
by temporarily breaking the 2x2x3 you can very quickly rotate edges and
move corners. On average, you can get the edges correctly rotated in about
5 moves. You could probably move the corners too, in 2-3 more moves, but
it's too hard to see the corner condition to do this while speed cubing.
But if you like, you can do 5 before 4.
3. flip the edges (intuitive/pattern)
4. expand to 2x3x3, using only the 2 free layers (intuitive)
5. move corners (pattern)
6. rotate corners (pattern)
7. move edges (pattern)
Step 4 can be quite hard before you're used to the problems. The others
should be simple for anyine familiar with the cube.
In reality, there are so many special cases in the final layer that 5-7
really is just one phase to solve the final layer.
Using this method, I use on average 60 moves while speed cubing, and I have
done 100 consecutive solutions in an average of 50.53 moves, while taking
time to think about what I'm doing.
> Do
>most speed people only use patterns? (or at least after the top layer?) How
>many patterns do you use? When I go for speed, I tend to use two patterns
>for step 2, and 4 possible patterns for step 3. Meaning that I use about
>7 patterns max for speed and I use 3 patterns total when doing it casually.
Well, for the final layer I use maybe 20-50 different patterns.
Singmaster asked all the 19 finalists in the Budapest world championship
what method they used. According to him, half used Minhs method, half used
another method, and I was the only one using something else.
- - - -
For every economist, there exists an equal and opposite economist.
Lars Petrus, Sunnyvale, California - lars@netgate.net