# Message #3943

From: Joel Karlsson <joelkarlsson97@gmail.com>

Subject: Re: [MC4D] Physical 2x2x2x2 - Canonical moves

Date: Tue, 09 Jan 2018 22:05:16 +0100

Hello everyone,

Personally, I think it’s a great idea to use a few different set of moves.

There are, however, particularly two sets that I’m interested in:

1) The pure moveset: Only including elementary twists and rotations this

moveset is really as pure as it gets. For the physical puzzle, some

rotations have to be performed as sequences of other moves and within these

sequences all moves are legal (even taking the puzzle apart and putting it

back together again). My notation is complete with respect to this moveset;

the R, L, U, D, F, B, C and E moves describes the twists and O, G and I can

be used for the rotations (‘I’ is sufficient to describe all rotations but

if O and G are used when possible, I will only be used for the rotations

which have to be performed as sequences). Note that the I notation says

nothing about how to perform the rotation, only what it does (and this is

probably necessary since everything is allowed during the rotation

sequences).

2) The +S moveset: Including all moves above and adding an extra two: the S

moves (see my latest post on notation for a new definition!). This moveset

adds as little as possible to the pure moveset to still be able to reach

all of the 2^4’s states and allow all legal moves at all times (in contrast

with the arbitrary moves which could be used within but not outside of a

rotation sequence in the previous moveset). My notation is complete with

respect to this moveset. This is the moveset I’ve used for speedsolving and

with which my current personal best is 3:50.83 (I haven’t speedsolved since

the post in which I announced that time).

Vocabulary:

elementary twist: a move rotating the set of pieces which all have a

sticker in a specific cell (the only twists possible in MC4D)

rotation: a move that doesn’t change the state of the puzzle

Best regards,

Joel

2018-01-06 4:32 GMT+01:00 Luna Peña scarecrowfish@gmail.com [4D_Cubing] <

4D_Cubing@yahoogroups.com>:

>

>

> No, it’s ok. I do see your point, I just think it’s worth the little

> distinction. However, if it turns out that times are very similar with

> both, that would be what would be most likely to change my mind.

>

> I’m glad it seems like we all agree on the whole though.

>

> ~Luna

>

> On 6 Jan 2018 03:28, "Melinda Green melinda@superliminal.com [4D_Cubing]"

> <4D_Cubing@yahoogroups.com> wrote:

>

>

>

> Sure, but all compound moves can similarly be avoided. Of course this move

> saves such little effort, it’s not a big deal to avoid it, but I showed it

> because it gives a good example of a compound move and it does turn out to

> be useful and prepares the viewers for the whole puzzle reorientation. Of

> course you’re entitled to your opinion, and that’s the purpose of this

> discussion. I hope you don’t take my challenging of your ideas as me

> injecting my own opinions.

>

> *Public Service Announcement: I apologize to all the lurkers for my large

> number of low-quality messages. For new members, know that this will die

> down. I trust you to ignore and delete messages on any subject that does

> not interest you. Also I’ll point out that you can change **your group

> subscription preference

> <https://groups.yahoo.com/neo/groups/4D_Cubing/management/membership>**

> to daily-digest or other setting if you want fewer messages filling your

> in-box.*

>

> So here is a recap of where people have appeared to have drawn lines at

> the moment. I’d still love to pin down Joel and Marc, and anybody else who

> has an opinion.

>

> 1 Simple rotations

> 2 90 degree twists of outer face

> 3 180 degree twists of side face

> 4 Center face axial twist

>

> Melinda - Primitive (plus #8)

>

> 5 Arbitrary half-puzzle juxtapositions

>

> Luna - Primitive

>

> 6 Clamshell move

> 7 Whole-puzzle reorientations

> 8 90 degree twist of side face (each 2x2x1 square rotate in opposite

> directions)

>

> Luna - Canonical (minus #6)

> Roice - Canonical

> Melinda - Canonical

>

> 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

>

> Thanks all!

> -Melinda

>

>

> On 1/5/2018 6:49 PM, Luna Peña scarecrowfish@gmail.com [4D_Cubing] wrote:

>

> I hadn’t seen that, or at least I forgot about it.

> I still think it needs labeling though, because you could just do the 180

> twists instead.

>

> This matters, because doing the clamshell would cut down on times, and I

> think any sort of shortcut like that should be kept separate. The physical

> move count of a speedsolve should equal the virtual twist count of the same

> scramble, and a clamshell would be one physical move for three virtual

> moves.

>

> The R L moves are ok because you still have to physically do both twists.

> It’s essentially a fingertrick.

>

> (I’m thinking more about speedsolving than fewest moves)

>

> ~Luna

>

> On 6 Jan 2018 02:43, "Melinda Green melinda@superliminal.com [4D_Cubing]"

> <4D_Cubing@yahoogroups.com <4D_Cubing@yahoogroups..com>> wrote:

>

>>

>>

>> #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:

>>

>> 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.

>>

>> ~Luna

>>

>> On 6 Jan 2018 02:32, "Melinda Green melinda@superliminal.com

>> [4D_Cubing]" <4D_Cubing@yahoogroups.com <4D_Cubing@yahoogroups..com>>

>> wrote:

>>

>>

>>

>> 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

>>

>>

>> On 1/5/2018 6:07 PM, Luna Peña scarecrowfish@gmail.com [4D_Cubing] wrote:

>>

>> OK. Given that, I’d say that:

>>

>> 1-5 are primitive.

>>

>> 7-8 are canonical.

>>

>> (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.)

>>

>> 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.

>>

>> 12 is unacceptable.

>>

>> ~Luna

>>

>> On 6 Jan 2018 01:45, "Melinda Green melinda@superliminal.com

>> [4D_Cubing]" <4D_Cubing@yahoogroups.com <4D_Cubing@yahoogroups..com>>

>> wrote:

>>

>>

>>

>> Certainly.

>>

>> #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.

>>

>> #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.

>>

>> #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>.

>>

>> -Melinda

>>

>>

>> On 1/5/2018 9:54 AM, Luna Peña 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

>> [4D_Cubing]" <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.

>>>

>>> 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:

>>>

>>> 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

>>>

>>

>>

>>

>>

>>

>>

>

>

>