Message #3925

From: Luna Peña <>
Subject: Re: [MC4D] Physical 2x2x2x2 - Canonical moves
Date: Fri, 05 Jan 2018 19:03:55 +0000

Wait, I thought you could run into permutation parity by only turning the
faces of one 2x2x2, because when you do an RKT adjacent swap, you can’t do
it without offsetting the opposite cell. Am I wrong?

But otherwise, I agree that multiple rule sets should exist, similar to how
there are macro and non-macro MC4D solves.

In terms of records on the physical puzzles, I think any times or move
counts you should specify what moves you used/allowed, because otherwise
whomever has the loosest moveset would have a better chance to hold the


On 5 Jan 2018 18:51, "Marc Ringuette [4D_Cubing]"
<> wrote:

I think that in a year, there will be 2 or 3 rule sets in common use.
This is a good thing.

As Roice says, it’s pretty clear that for a good 2^4 hypercube
correspondence, all twists should alter 8 piece positions at a time.
We may end up with multiple rule sets that obey this constraint (and,
for instance, allow or disallow various physical macros and/or virtual
macros for moves that do not have a 1-1 correspondence; if you recall,
the whole puzzle cannot be solved without at least one such move).
Bob and Joel both used versions of this approach, and will perhaps
provide us with more detail about what they did.

It’s also pretty clear that another nice way to use the puzzle involves
allowing 4-cycles. Both I (a few months ago) and Zander (in his video
just now) gravitated naturally to solve the puzzle that way. It makes
the puzzle easier, but not absurdly easy, and still lets us encounter
fun 4D challenges. It’s also less likely that you will accidentally
find yourself in an illegal parity state: permutation parity does not
exist, and as long as you don’t drop the puzzle in such a way that
single pieces are ejected, orientation parity will not be violated
either. This bypasses one modest "pain point" of the other rule sets,
where you discover toward the end of a solve that you have been in an
illegal permutation parity state all along, due either to sloppy
scrambling or a slip of the hand during the solve.

So, let’s remember not to think of "legal move" as a single binary
distinction that will apply to all users of the puzzle. Let’s define,
and name, multiple rule sets and see what we like!