Simplifying scrambles for big cubes

[Tomas Kristiansson]

Hi

At my last competition where I scrambled some 7x7x7's I realised that there might be an easier way to scramble big cubes, to both make the scrambling faster and less prone to errors.

In the example of 7x7x7, instead of having 10*10 random moves where each move is of random depth, we could instead group the moves of the same depth together, and then end the scramble with a mixed depth (which probably is needed to reach more states).

A very short scramble example for clarification:

U L2 B' F2 D (depth 1)

Fw Dw' Lw2 Bw Uw' (depth 2)

3Bw 3Dw2 3Rw2 3Fw' 3Dw (depth 3)

3Uw2 F2 Bw 3Lw' R2 (mixed depth)

The depth 1-3 can probably be taken from optimal 3x3 scrambles (which Daniel Sheppard suggested to me), potentially shortening the 7x7x7 scrambles by 10-20 moves (depending on how long the mixed depth is).

Since I am not a puzzle theorist I leave it to you to decide if this is a good or bad idea, but I think this could speed up the big cube events slightly, and also make life easier for those who want to help out scrambling at competitions :-)

Kind regards,

Tomas Kristiansson

[Pedro Santos Guimarães]

Seconded!

--

---
You received this message because you are subscribed to the Google Groups "WCA Software Team" group.
To unsubscribe from this group and stop receiving emails from it, send an email to wca-software...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/wca-software/CAFyYESNcQRX%2BKV0AqO64-34YNVTNhkx%2B_QmPEmkTjGaRkpqkgA%40mail.gmail.com.
For more options, visit https://groups.google.com/d/optout.

[Lucas Garron]

Not a bad idea, but I'd like to make sure we analyze the resulting distributions of centers, at the very least.
With scrambles, we should be careful about any "looks good enough" conclusions, but we could probably get with a significantly shorter "mixed" phase.

Crazy idea: could we A/B these in competition, once we're pretty sure we want to go with it?

e.g. each individual scramble in competition is randomly either an old scramble, or a new scramble. A competitor will typically receive at least one of each during a round, but they won't know which.

Since we have identical scrambles for final rounds (or use the same pattern of new vs. old for multiple groups in the same round), we can analyze if people seem to be getting faster times on the new ones – that would make for a good signal that no one is getting an advantage in practice (yet).

»Lucas

To view this discussion on the web visit https://groups.google.com/d/msgid/wca-software/CAM6J6Bwa%3DoaQkr_bhWFC6zE0dmWnf1Jf4nsTMUPo%2BQ8qVBUbrw%40mail.gmail.com.

[Sébastien Auroux]

In general I like the idea. I just hope that everyone is aware that we need the mixed phase for sure, otherwise you can just solve e.g. a 7x7x7 with three 3x3x3 stages. :)

To view this discussion on the web visit https://groups.google.com/d/msgid/wca-software/CAO6LD_CStQycYHx1isVca%2B8PSdDLrPc6s73xTWsU_JgqvrQgBw%40mail.gmail.com.

[Ron van Bruchem]

I checked with Jaap and he thinks it is a good proposal. He says it is good to have minimum requirements for the mixed phase, for example at least three moves of each type.

To view this discussion on the web visit https://groups.google.com/d/msgid/wca-software/CAF2SvPU9tYauvxZgrLTQGB0c52pHOK__0pFkppCTpKNPukp%3DqQ%40mail.gmail.com.

[Ron van Bruchem]

Click send too early. Sorry.

Jaap suggests the following:
1) scramble single moves
2) scramble double moves
3) scramble triple moves
4) 5 sets of (single, double, triple move)

[Pedro Santos Guimarães]

But how many moves does each phase require?

[Ron van Bruchem]

20, 20, 20, 15 max

[Pedro Santos Guimarães]

Does that scramble the cube "good enough"?

If so, I'm totally happy to adopt this. Scrambling those cubes is currently difficult because of the long scrambles and not-so-good puzzle quality. It took me more than 2 minutes to scramble my 7x7 yesterday :P And 6x6 was like 1:30.

Shorter and simpler scrambles sound very good.

[Ron van Bruchem]

Yes, according to Jaap this is a valid method for scrambling. He did not do a mathematical analysis but I trust his gut feeling.

[Jeremy Fleischman]

I've created https://github.com/cubing/tnoodle/issues/194 to track this. FYI, I'm not planning on working on this anytime soon. If anyone is interested, they should feel free to take this on.

To view this discussion on the web visit https://groups.google.com/d/msgid/wca-software/CADFe%2BGgpC_Ug4zNQKQD3oBbgZ8yCOzR%3DhAZcov5rJgCJEvXUTQ%40mail.gmail.com.