Message #3619

From: mananself@gmail.com
Subject: Re: [MC4D] Remembering Andrey Astrelin
Date: Fri, 27 Jan 2017 13:19:05 -0800

I am solving the 48-cell FT Mirror Z as I planned. With 1200 nontrivial pieces, it’s about half of a 120-cell FT.

There are two types of 2C pieces, corresponding to triangular and octagonal faces respectively. The octagonal 2Cs are partitioned into 18 orbits whereas the triangular 32 orbits. Each turn changes the parities of permutation in 3 octagonal orbits and 4 triangular orbits. Overall the parity situation is very complicated, which is the main challenge of this puzzle.

I solved the octagonal 2C orbits intuitively. Then the triangular orbit parities were harder to deal with, because you cannot change the parity of a single orbit, or two, or four. In fact, with the help of computer, I found that any sequence maintaining the parity of octagonal orbits, will flip the parities of 0, 16, or 32 out of 32 triangular orbits.

I reused some scripts I wrote when I tried to figure out the parity situation on 120-cell Mirror Z with the help from Andrey.

So far I’ve solved 2C and 3C and am working on 4C. It’ll take a few more days.

Nan

—In 4D_Cubing@yahoogroups.com, <roice3@…> wrote :

Doing a memorial solve is a really lovely idea, Nan. I’ve always wanted to finish one of the MHT633 puzzles, so I started anew on the 12-colored version after reading your email. It will take me some time, but as you say, this is a nice way to remember Andrey.

So far, I think the 12C puzzle is a natural choice for those who have solved the 3^4. It’s a lot like that puzzle in that it has 3 layers of 3-dimensional faces: a bottom face, 9 center section faces, and 2 opposing top faces. The fact that each face has two opposites reminds me of the Klein Quartic puzzle in MagicTile, and will provide an extra challenge when finishing up piece types. Working layer-by-layer, one will almost certainly end up with some pieces that need to be moved to a non-adjacent face.

As usual for me, I’m tackling it by piece type, doing 2C pieces (9 per face, 54 total), 3C pieces (27 per face, 108 total), and finally 4C pieces (18 per face, 54 total). Hopefully I counted those right. I’m finding Andrey’s setup move and piece finding functionality really helpful. I haven’t used macros yet, but I think they will become important later.

The most challenging aspect so far is getting used to looking out into hyperbolic space. Everything is so "squashed" together and pieces are often occluded by material in front, but I’m getting more used to it. I like having the "Area Center" slider setting mostly to the left. I haven’t done any solving in the Poincaré Ball view yet, but I might try that some too.

I’ll report back when I’m done (at least weeks, maybe longer since I’m not rushing). And if others want to try, you can download MHT633 here http://cardiizastrograda.com/astr/M3dHT633/.

Roice

On Sun, Jan 15, 2017 at 1:06 AM, mananself@… mailto:mananself@… [4D_Cubing] <4D_Cubing@yahoogroups.com mailto:4D_Cubing@yahoogroups.com> wrote:

These two days, I went through some old posts by Andrey. Those about the 120-cell Mirror Z (120Z) reminded me of a long and challenging solve.

I’ve been thinking about doing or making something to remember Andrey. I may do a memorial solve on Magic Puzzle Ultimate (MPUlt). I’m thinking about 48-cell FT Mirror Z. The number of pieces is about half of 120-cell. The parity situation can be pretty challenging, which will give me enough time to think about him.

I encourage everyone to try some puzzles created by Andrey. My favorite is MPUlt, which has a large collection of different shapes in 4D. The latest binary (v1.53) is here:
https://www.dropbox.com/s/xm5p y39jec0nl1q/MPUlt1.53.zip https://www.dropbox.com/s/xm5py39jec0nl1q/MPUlt1.53.zip

His latest puzzle definition file is here:
https://www.dropbox.com/s/b96c e6cbau4txd6/MPUlt_puzzles.txt https://www.dropbox.com/s/b96ce6cbau4txd6/MPUlt_puzzles.txt

Nan

—In 4D_Cubing@yahoogroups.com mailto:4D_Cubing@yahoogroups.com, <roice3@…> wrote :

Thank you for letting the group know Nan. Andrey influenced me so much, and this news is very sad. I will miss him.

I have many memories of Andrey, but thought I would share a few of my favorites…

When he released MHT633, Andrey did not even tell us what it was - he let us guess! That was a fun way to announce it, and I still recall the excitement and joy investigating that amazing puzzle abstraction. The surprises were wonderful. It introduced me to exotic hyperbolic honeycombs for the first time, which have held my interest ever since, and he subsequently shared many further insights about them with me. To date, his MHT633 is still the coolest puzzle in my mind, abstracting so many different features of the original Rubik’s cube. I like the way Andrey would blow my mind by conjuring up something way beyond my current thinking.

I loved reading Andrey’s emails for all their insights. Often I would need to read them a number of times. When he turned his attention to MagicTile, he noticed all sorts of things I hadn’t considered. He pointed out how one of the {8,3} 6C puzzles was combinatorially the Rubik’s cube in disguise. He had thoughts on what colorings would work and helped me map out identifications for the {8,3} 24C. He appreciated the beauty of certain puzzles and encouraged their creation - for example, he requested the hemi-Megaminx and knew it would be a special puzzle. He ended up digging into the configuration files and building some of his own. He had a great mind.

For those who were friends with Andrey on facebook, folks are leaving messages on his page here https://www.facebook.com/astr0073/posts/1650043985296523.

Roice

On Fri, Jan 13, 2017 at 10:24 AM, mananself@… mailto:mananself@… [4D_Cubing] <4D_Cubing@yahoogroups.com mailto:4D_Cubing@yahoogroups.com> wrote:

I was so saddened to hear the tragic news that the member of our group, the creator of many high dimensional puzzles, lost his battle to cancer. It is a huge loss to his family and our little community.

Andrey is the most creative, productive, talented, and passionate person I know in this group. Many of us played the puzzles he created and are inspired by them. Snippets from the MC4D website:

"In 2010, Andrey Astrelin joined our community and immediately broke several of our most cherished records. Not satisfied, he then wrote and released his own seven dimensional version! MagicCube7D solves the problem of visualizing such a high-dimensional object by starting with our now-familiar 4D projection and then partially unrolling the last three dimensions using a clever fractal-like design. Not just one puzzle this amazing piece of code supports all 12 cubes from 34 through 57. Oh and then he went and solved the 37."

"Magic Puzzle Ultimate also from Andrey is his version of MagicCube4D. The user interface is quite different and some experienced users prefer it. It includes some unique and special puzzles such as the much desired and very difficult 24-cell, the 48-cell, the 600-cell along with deep-cut truncated, runcinated, rectified, and snub versions of many of these plus some 5D and 6D puzzles."

"Magic Hyperbolic Tile {6,3,3} from Andrey is the 3D version of Roice’s MagicTile because it lives in a hyperbolic 3-space. This puzzle turns out to be devilishly hard but also gloriously beautiful to behold."

I enjoyed discussing geometry and puzzles with Andrey in this group. His great ideas and deep understandings enlightened us.

Andrey loved puzzles so much. His family told me, that "he deals with puzzles till the last days."

Let’s take a moment to remember Andrey. To me, Andrey moved to higher dimensions. I’m sending my deepest condolences to his family.

Sincerely,

Nan Ma