# Message #1928

From: Melinda Green <melinda@superliminal.com>

Subject: Re: [MC4D] Re: 24-cell solved

Date: Tue, 15 Nov 2011 18:33:13 -0800

Now we have more than just Nan on the boards for the MPUlt puzzles! Yea!

The 24-cell appears to have not disappointed those who have only dreamed

of it for so long. I hope to see more names on the 24-cell HOF

<http://wiki.superliminal.com/wiki/MPUlt_24-cell_Puzzles> soon, and I’d

really love to see a healthy competition for the shortest solution. I’m

guessing that 10k twists is within reason. What will it mean to

eventually tame this beast? Is there anything more to learn here that

the other puzzles haven’t given us?

Thanks for this special puzzle, Andrey, and congratulations on your

latest solution.

-Melinda

On 11/15/2011 5:28 PM, Andrey wrote:

> Nan,

> "Optimization" is an item in "Edit" menu. It combines sequential twists around the same axis, and removes pairs of opposite twists.

> For example, if you apply this feature to your solve of 24cell, it’ll reduce number of twists from 54199 to 35819 :)

>

> Andrey

>

> — In 4D_Cubing@yahoogroups.com, "schuma"<mananself@…> wrote:

>> Congratulations!

>>

>> I pull out my notes, and find my order different. My order is: 2C faces, 3C edges, 6C corners, and then 1C inner corners, and the last step is 2C side-face pieces.

>>

>> Before solving, I prepared a long macro for fixing the parity issue you mentioned, so that even if it occurs I’m not upset.

>>

>> I’m wondering what is the "optimization" about the number of twists?

>>

>> Nan

>>

>> — In 4D_Cubing@yahoogroups.com, "Andrey"<andreyastrelin@> wrote:

>>> Finally I’ve got some time to work on 24-cell. Solve was easy enough until the last step (6C pieces) where I discovered that my ideas of moving them don’t work: I can’t find easy operations that move 6C and don’t move sub-corners. But it happened that my operations for moving sub-corners don’t move corners! So I returned to the start of sub-corner positioning step and started to work on 6C instead.

>>> Total twist count (after optimization) is 21137. Half of them (10606) was spent on first 4 steps, and second half - on last two. The longest operation (3-cycle of 6C) was 139 twists long.

>>> And I was lucky that I didn’t meet parity problem at the end of 3C pieces stage: elementary twist of the cell gives even permutation of central 2C, but odd permutations of 3C and 6C. So it’s possible that you’ll need to re-solve eight 2C pieces when you think that you’ve done with them long time ago :)

>>>

>>> Andrey

>>>

>

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