Message #1057

From: Brandon Enright <bmenrigh@ucsd.edu>
Subject: Re: [MC4D] 2-c parity(?) problem with 4^4
Date: Wed, 21 Jul 2010 17:57:32 +0000

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On Wed, 21 Jul 2010 13:53:56 -0000
"deustfrr" <deustfrr@yahoo.ca> wrote:

> I have a problem with the last 2 faces
> http://groups.yahoo.com/group/4D_Cubing/photos/album/346940124/pic/list
> reply please
> (I got parental controls on time so I just type that, lolz)
>

deustfrr,

Your images are quite hard (for me) to see the exact problem in context.

However, for your "1-c piece situation" image, you have what appears to
be a blue and an orange 1-c central piece swapped. If you were solving
purely intuitively then you may have a bit of trouble solving this but
if you have a 3-cycle for the 1-c pieces then just swap two
indistinguishable pieces such as two blue in the 3-cycle along with the
orange.

For your "2-c piece parity 1b" and "2-c piece parity 1a" images, this
isn’t really a parity but they must be solved together.

I recently discussed a semi-generic technique for doing this on almost
any puzzle here:
http://www.twistypuzzles.com/forum/viewtopic.php?f=8&t=7830&p=219422#p219422
The general idea is to 3-cycle your two flipped pieces along with some
other (choice is arbitrary) piece such that one of the flipped pieces
moves into the place of the other flipped piece (call this sequence X).
Then flip the whole group over and put it back in place (call this Y),
then undo X, then undo Y. This technique will work in any number of
dimensions.

Good luck,

Brandon

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