Message #3935
From: Melinda Green <melinda@superliminal.com>
Subject: Re: [MC4D] Physical 2x2x2x2 - Canonical moves
Date: Fri, 05 Jan 2018 18:42:08 -0800
#6 is equivalent to three simple 180 degree twists like I demonstrated here <https://www.youtube.com/watch?v=_D4m1Kit3TI&t=1m58s>.
-Melinda
On 1/5/2018 6:35 PM, Luna Peña scarecrowfish@gmail.com [4D_Cubing] wrote:
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> I see 5 as the equivalent of doing R L on a 2^3, which is obviously just two twists. However, it is not as obvious to me how 6 is simple twists. Perhaps when I get my puzzle and see exactly what it does to the puzzle, I’ll change my mind, but I would only class moves that are simple on both the physical and virtual puzzle as primitive.
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> ~Luna
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> On 6 Jan 2018 02:32, "Melinda Green melinda@superliminal.com <mailto:melinda@superliminal.com> [4D_Cubing]" <4D_Cubing@yahoogroups.com <mailto:4D_Cubing@yahoogroups.com>> wrote:
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> That’s very helpful, Luna, but I’m curious: Why do you see #5 as primitive but not #6? Seems to me like it should be both or neither.
> -Melinda
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> On 1/5/2018 6:07 PM, Luna Peña scarecrowfish@gmail.com <mailto:scarecrowfish@gmail.com> [4D_Cubing] wrote:
>> OK. Given that, I’d say that:
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>> 1-5 are primitive.
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>> 7-8 are canonical.
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>> (The rest of ROIL (as in, other twists of the centre 2x2x2 and the restacked IO twists) may be canonical or may require labeling. I am unsure.)
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>> 6&9(&10?) only with clear labeling (ie. counted as a separate kind of solve, like macro vs non-macro in MC4D). 11 could possibly be included at a stretch.
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>> 12 is unacceptable.
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>> ~Luna
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>> On 6 Jan 2018 01:45, "Melinda Green melinda@superliminal.com <mailto:melinda@superliminal.com> [4D_Cubing]" <4D_Cubing@yahoogroups.com <mailto:4D_Cubing@yahoogroups..com>> wrote:
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>> Certainly.
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>> #4 is a twist of the central 2x2x2 block about the long axis. It is a twist of the face joining the two halves of the puzzle. It is equivalent to twisting both end caps the opposite direction.
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>> #5 is the first "compound move" that I talk about in the video here <https://www.youtube…com/watch?v=_D4m1Kit3TI&t=1m39s> as a natural consequence of combining simple rotations with 90 degree twists.
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>> #7 is the fancy 4D change of projection described in the first link in the description here <https://www.youtube.com/watch?v=d2Fh_1m0UVY>.
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>> -Melinda
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>> On 1/5/2018 9:54 AM, Luna Peña scarecrowfish@gmail.com <mailto:scarecrowfish@gmail.com> [4D_Cubing] wrote:
>>> Can I get clearer definitions of 4, 5 and 7?
>>>
>>> ~Luna
>>>
>>> On 4 Jan 2018 23:28, "Melinda Green melinda@superliminal.com <mailto:melinda@superliminal.com> [4D_Cubing]" <4D_Cubing@yahoogroups.com <mailto:4D_Cubing@yahoogroups.com>> wrote:
>>>
>>> First off, please check out Zander Bolgar’s lovely solution video <https://www.youtube..com/watch?v=fYxn4wPe2ZE> that he invited me to share. It’s very cool to see someone developing something like finger tricks and blasting through a solution. It’s very much like Bob’s <https://groups.yahoo.com/neo/groups/4D_Cubing/conversations/topics/3803> and Joel’s <https://groups.yahoo.com/neo/groups/4D_Cubing/conversations/messages/3904> solutions as well as Marc’s <https://www.youtube.com/watch?v=pKHU5sFaGvY> approach.
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>>> This makes for a great launching point for questions about which moves should be included in a canonical set. Of course any move that results in a reachable state can be justified in a solution, but there’s such a spectrum from "obviously fine" to "obviously not". Now that we’ve gotten some experience with this puzzle and the practicalities of solving it, I feel it’s time to see if we can find some sort of natural canonical set, so I’d love to hear your thoughts.
>>>
>>> Here is the list of moves I know about, loosely ordered as described above:
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>>> 1. Simple rotations
>>> 2. 90 degree twists of outer face
>>> 3. 180 degree twists of side face
>>> 4. Center face axial twist
>>> 5. Arbitrary half-puzzle juxtapositions
>>> 6. Clamshell move
>>> 7. Whole-puzzle reorientations
>>> 8. 90 degree twist of side face (each 2x2x1 square rotate in opposite directions)
>>> 9. Single end cap twist (with parity restrictions?) [fine for scrambling]
>>> 10. Restacking moves [fine for scrambling]
>>> 11. Single piece flip
>>> 12. Reassemble entire puzzle
>>>
>>> I suspect the trickiest part has to do with #9 which is the one I would most like to nail down.
>>>
>>> I intend to create a follow-up video to talk about all of these and any others you can think of. The way you can help is to offer additions and corrections to the above list, and especially in suggesting ways to reorder it. Then please suggest where you’d draw three lines:
>>>
>>> * Everything above is primitive (Or "basic" or "elementary" as Joel calls them)
>>> * Everything above is canonical. IE always acceptable in solutions
>>> * Nothing below is acceptable in solutions.
>>>
>>> Thanks all!
>>> -Melinda
>>>
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