Message #3654

From: Melinda Green <melinda@superliminal.com>
Subject: Re: [MC4D] Re: Physical 4D puzzle achieved
Date: Thu, 16 Feb 2017 15:53:07 -0800

On 2/16/2017 2:09 PM, Roice Nelson roice3@gmail.com [4D_Cubing] wrote:
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>> 1. If we were to allow interim jumbling, I think we can get 90-degree twists of the blue and orange faces. Instead of performing a 180-degree rotation maneuver here, you would take the 4x2 block and translate it a step. The end result would be a 3x2x2 with two 2x1 blocks protruding off of it on opposite sides. But then you could just do a reorientation by rolling one of those protrusions around to meet the other and recover the original 4x2x2 block. Hope this is clear.
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> I think the shearing step is clear enough though I’m not sure what orientation you intend the 2x1 block to end up in. Regardless, that would look like an even stranger result than anything I’ve seen so far because half of the pieces would have single stickers at the corners, and half would have 3-color junctions. I had been calling such oddly reoriented pieces "inverted", but is "jumbled" the more correct term? It would be nice if the terms jumbled and bandaged are the correct analogies.
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> I’m using "jumbled" to mean something else, like this <http://twistypuzzles.com/articles/other-twistypuzzlesthatjumble/>. IOW, I was using jumbled to mean allowing moves that don’t result in the 4x2x2 block. Sounds like there are 3 separate terms here.

That sounds good. I’ll keep using the other two terms until better ones come along.

I’m still having trouble understanding the exact unjumbling move and how this relates to a 90 degree twist. Using your shearing move but shifting it two 2 instead of 1 is much better behaved. I still don’t know what it represents but it’s interesting.

Currently, the only twist that appears to move stickers off the red-blue faces is turning the inner 2x2x2 black face, but that appears to require reorienting all those pieces at the same time. That seems impractical, so it looks like we’ll need to find something else if we’re going to reach the full state space.

>> I want one Melinda! When are you going to set up a shop? :D
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> Well the first question is which version do you want? The bandaged (current) version or Matt’s more general arrangement? I’m working with the dice guy right now to see if and how the 24 magnet pieces might be made and what they will cost. The magnets will likely need to be recessed so that it’s not too hard to turn. That means either an extra step to fill in the gaps, or just sticker over them. The nice thing is that none of the diagonal sticker cuts will cross any magnets.
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> I’m happy to produce these for group members at cost, at least until it becomes too much work. It took me nearly 4 hours to sticker this one (nearly 200 triangles!) but I’m sure that with practice, I can soon do it in under 2 hours.
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> I think I’d like to buy whatever version evolves from this thread that we know will support the full 2^4 permutation group (though it would be cool to have both). I’d be happy to sticker it myself. I recently bought a Tuttminx <https://en.wikipedia.org/wiki/Tuttminx> that came unstickered, and stickering it took me a similar amount of time.

No problem. The trick it to take your time aligning the diagonals perfectly so there is no gap or overlap. Also important is to never open the puzzle by pressing your fingernail between the pieces because that messes up the stickers. Instead you need to pull off whole slabs, and you have to instruct people not to use their fingernails when you hand it to them. Does anyone know of a good source of tile stickers?

-Melinda