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Date: Fri, 04 Dec 1998 13:07:36 -0500
To: Jacob Davenport
From: Nichael Lynn Cramer
Subject: Re: (5x5x5) edge parity corrections
Cc: Cube Lovers
In-Reply-To: <00096300.C22092@scudder.com>
Jacob Davenport wrote:
>I don't like the edge parity correction move that I use in my solution, and
>I'm hoping that someone can give me a better one.
>
>The parity problem is found in 5x5x5 cubes (and 4x4x4 cubes, I understand)
>when two of the edges right next to the corners (which I call "wings") are
>switched. Some fairly simple moves can get all three edges in line with
>each other, but half the time two wings need to be switched. By the time I
>figure this out when doing a 5x5x5 cube, I've solved most of it, and my
>parity fixing move messes up many of the edges I've been working on.
>
>How do other people fix this problem?
>
>-Jacob
Hi Jacob
In both cases (4X and 5X) I solve this problem in the following way:
1] I solve the rest of the cube, leaving me with the two "switched wings"
(in your terminology).
2] I then arrange things so both "wings" are on the same
"off-center-slice". (Also it will always be the case that both of these
winds are now on the same face.)
This will be easy to do using the 3-wing swapping operators.
3] At this point I now rotate the "off-center-slice" containing the
"switched wings" by a quarter turn.
As a result of this move it will be the case that that the
"off-center-slice" now has one of the previously "switched wings" in its
"correct cubicle". The other three "wings" will be now be in a cyclic
permutation.
4] Since --from your note above-- I assume you understand how to cycle
three "wings", all you have to do now is put the "wings" in the right place
and replace the damage to the off-center central faces that were messed up
during that initial quarter-turn above. (And since they are in "paired"
clusters, this should be pretty straightforward.)
(In short, the quarter-turn of the non-central slice puts the cube back in
the proper "orbit" for finishing up.)
Now clearly this is far from maximal. And it's certainly not terribly
fast. But I find it a very simple, and an easy (and easy-to-remember [and
easy-to-explain]) way to clean up this potentially messy situation.
Hope this helps
Nichael
--
Nichael Cramer
nichael@sover.net deep autumn--
http://www.sover.net/~nichael/ my neighbor what does she do