Thread: "Stellated intersection of cylinders"

From: mananself@gmail.com
Date: 20 Feb 2017 20:10:47 +0000
Subject: Stellated intersection of cylinders




From: Melinda Green <melinda@superliminal.com>
Date: Mon, 20 Feb 2017 20:16:04 -0800
Subject: Re: [MC4D] Stellated intersection of cylinders



--------------58FB47CDA1ADDAEF0408054B
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit

I've not examined these very closely, but to me they look more like unions of intersections than stellations of intersections. As you suggested, both views may be correct though it seems more natural for me to see this approach as starting with a symmetric set of intersecting cylinders and unioning all possible intersections of N of them. For example, the 6-cylinder Magaminx is the union of all possible triplets of cylinders (6 choose 3). This 3-cylinder 2x2x2 is the union of all pairs of 3 (3 choose 2)., whereas this one is 3 choose 3. Twists are always around one cylinder. For 10 cylinders, that doesn't add up to 11 choices though. Maybe it's every possible fully-symmetric way to choose 3, 4, or 5 cylinders out of 10?

This does seem like a very clever idea and may even extend nicely into higher dimensions.

-Melinda

On 2/20/2017 12:12 PM, mananself@gmail.com [4D_Cubing] wrote:
>
>
> Recently I saw these puzzles created by Alexandr Abalikhin (twistypuzzles ID: TER)
>
>
> http://twistypuzzles.com/cgi-bin/pdb-search.cgi?&act=inv&key=784&off=0
>
> http://twistypuzzles.com/cgi-bin/pdb-search.cgi?&act=inv&key=784&off=15
>
> https://www.youtube.com/channel/UCUyPm2UVtP_GQloD4U7BVeQ
>
>
> The puzzles with names including fourcylinder, sixcylinder, tricylinder intrigued me. Recently he constructed tencylinder puzzles:
>
>
> http://twistypuzzles.com/forum/viewtopic.php?f=15&p=361084#p361084
>
>
> These puzzles are shape mods. But the shapes are very interesting. I consider them as different levels of stellation of the intersection of cylinders.
>
>
> The intersection of three orthogonal cylinders is well known and is a Steinmetz Solid. He made this puzzle based on it:
>
> http://twistypuzzles.com/cgi-bin/puzzle.cgi?pkey=5346
>
>
> Then he extended the surfaces of the cyli nders, until two meet, to get this shape:
>
> http://twistypuzzles.com/cgi-bin/puzzle.cgi?pkey=5605
>
>
> You can think of the new shape as the region contained by at least two of the three cylinders. If you think of the original intersection as a "curvy" rhombic dodecahedron, then the new shape is a "curvy" stellated rhombic dodecahedron:
>
> https://en.wikipedia.org/wiki/First_stellation_of_rhombic_dodecahedron
>
>
> And Alexandr created stellations of intersections of more cylinders. I can see some corresponding "flat" stellated/compound polyhedra. But the curvy shapes are neat because one can construct them just out of cylinders.
>
>
> I searched online, and only found pictures of the union or intersection of cylinders, such as this page:
>
> http://paulbourke.net/geometry/cylinders/
>
>
> I haven't found anything about their stellations. Have mathematicians studied them? Are the 11 shapes in thi s page a complete enumeration of the stellations of 10 cylinders arranged in this manner?
>
> http://twistypuzzles.com/forum/viewtopic.php?f=15&p=361084#p361084
>
> How many such shapes are out there?
>
>
> Have you guys seen anything like this?
>
>


--------------58FB47CDA1ADDAEF0408054B
Content-Type: text/html; charset=utf-8
Content-Transfer-Encoding: 7bit






I've not examined these very closely, but to me they look more like
unions of intersections than stellations of intersections. As you
suggested, both views may be correct though it seems more natural
for me to see this approach as starting with a symmetric set of
intersecting cylinders and unioning all possible intersections of N
of them. For example, the href="http://twistypuzzles.com/cgi-bin/puzzle.cgi?pkey=5735">6-cylinder
Magaminx is the union of all possible triplets of cylinders (6
choose 3). This href="http://twistypuzzles.com/cgi-bin/puzzle.cgi?pkey=5605">3-cylinder
2x2x2 is the union of all pairs of 3 (3 choose 2)., whereas href="http://twistypuzzles.com/cgi-bin/puzzle.cgi?pkey=5346">this
one is 3 choose 3. Twists are always around one cylinder. For
10 cylinders, that doesn't add up to 11 choices though. Maybe it's
every possible fully-symmetric way to choose 3, 4, or 5 cylinders
out of 10?



This does seem like a very clever idea and may even extend nicely
into higher dimensions.



-Melinda



On 2/20/2017 12:12 PM,
mananself@gmail.com [4D_Cubing] wrote:





Recently I saw these puzzles created by Alexandr Abalikhin
(twistypuzzles ID: TER)





http://twistypuzzles.com/cgi-bin/pdb-search.cgi?&act=inv&key=784&off=0


http://twistypuzzles.com/cgi-bin/pdb-search.cgi?&act=inv&key=784&off=15


https://www.youtube.com/channel/UCUyPm2UVtP_GQloD4U7BVeQ





The puzzles with names including fourcylinder, sixcylinder,
tricylinder intrigued me. Recently he constructed tencylinder
puzzles:





http://twistypuzzles.com/forum/viewtopic.php?f=15&p=361084#p361084





These puzzles are shape mods. But the shapes are very
interesting. I consider them as different levels of stellation
of the intersection of cylinders.





The intersection of three orthogonal cylinders is well known
and is a Steinmetz Solid. He made this puzzle based on it:


http://twistypuzzles.com/cgi-bin/puzzle.cgi?pkey=5346





Then he extended the surfaces of the cyli nders, until two
meet, to get this shape:


http://twistypuzzles.com/cgi-bin/puzzle.cgi?pkey=5605





You can think of the new shape as the region contained by at
least two of the three cylinders. If you think of the original
intersection as a "curvy" rhombic dodecahedron, then the new
shape is a "curvy" stellated rhombic dodecahedron:


https://en.wikipedia.org/wiki/First_stellation_of_rhombic_dodecahedron





And Alexandr created stellations of intersections of more
cylinders. I can see some corresponding "flat"
stellated/compound polyhedra. But the curvy shapes are neat
because one can construct them just out of cylinders.





I searched online, and only found pictures of the union or
intersection of cylinders, such as this page:


http://paulbourke.net/geometry/cylinders/





I haven't found anything about their stellations. Have
mathematicians studied them? Are the 11 shapes in thi s page a
complete enumeration of the stellations of 10 cylinders arranged
in this manner?


http://twistypuzzles.com/forum/viewtopic.php?f=15&p=361084#p361084


How many such shapes are out there?






Have you guys seen anything like this?











--------------58FB47CDA1ADDAEF0408054B--




From: mananself@gmail.com
Date: 21 Feb 2017 05:33:20 +0000
Subject: Re: [MC4D] Stellated intersection of cylinders




From: mananself@gmail.com
Date: 21 Feb 2017 13:22:46 +0000
Subject: Re: [MC4D] Stellated intersection of cylinders





Return to MagicCube4D main page
Return to the Superliminal home page