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Harry Savage 17 FMC Single + Sebastiano Tronto 24.00 mean

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#7
Wow, that must have been an awesome scramble! Congratulations to all of them for making the most of it. Anyone know if the 17 was optimal?
It is, but for 18 move solutions and fewer, it is actually mathematically most likely that the solution is optimal, due to the rarity of the scrambles of length (solution length -1). Which explains why my 18 and Harry's 17 were both optimal. I guess Sebastiano's 18 was not, but we now have 3 data points anyhow that show 67% tying optimal for 18 or fewer
 

Mike Hughey

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#8
It is, but for 18 move solutions and fewer, it is actually mathematically most likely that the solution is optimal, due to the rarity of the scrambles of length (solution length -1).
A very cool fact.

So if I understand correctly, the chances of a scramble solvable in 16 moves is twelve times less likely than that of a 17-mover? So now a new, better WR is going to get a lot harder. And then about another factor of 12 to get to 15 moves? And even worse than that for 14?

On a slightly unrelated topic, it still bugs me a bit that we have fairly substantial minimum moves for random-state scrambles for most puzzles, but not for 3x3x3. Shouldn't we consider adding a minimum set of moves substantially greater than 2 for 3x3x3 scrambles?
 

h2f

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#9
Harry's solution from FB group. Thanks to Karol Zakrzewski:

Scramble: R'U'F D' L2 B2 R2 B2 U F2 D U F2 R2 F D R2 B L D' B2 R' D' F2 R' U' F
Inverse: F' U R F2 D R B2 D L' B' R2 D' F' R2 F2 U' D' F2 U' B2 R2 B2 L2 D F' U R

R L' D' L //eo [4/17]
(R2 F') //DR [2/17] (Domino Reduction)
U'R2 D' // 2x2 + sq [3/17]
L2 D' L2 D // EO on all axes + sq[4/17]
F2 U2 F2 L2 // finish [4/17]

Solution: R L' D' L U'R2 D' L2 D' L2 D F2 U2 F2 L2 F R2 [17]
Optimal is 17.
 
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#10
On a slightly unrelated topic, it still bugs me a bit that we have fairly substantial minimum moves for random-state scrambles for most puzzles, but not for 3x3x3. Shouldn't we consider adding a minimum set of moves substantially greater than 2 for 3x3x3 scrambles?
I've always thought this myself. The argument I've always heard is, "There's a negligible chance of a 2 or 3 move scramble actually showing up," but negligible =/= 0. If a 2-move scramble actually showed up in any 3x3 event, it would technically be legal. If this happens, it brings up a major issue regardless of the WCA's decision:
If the results are accepted, there would be a ton of community backlash (just look at the reaction to the 3.47 which was a perfectly legitimate scramble).
If, on the other hand, the WCA decides to DNF/use extras instead, then 2-move scrambles are not actually legal, and the regulations should not be written to imply such.

I agree that we should absolutely stop this beforehand instead of just waiting for some scramble like this to actually show up. (And while we're at it, can we change 5-7 and Megaminx to be over 2 moves as well?)
 
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#11
I've always thought this myself. The argument I've always heard is, "There's a negligible chance of a 2 or 3 move scramble actually showing up," but negligible =/= 0. If a 2-move scramble actually showed up in any 3x3 event, it would technically be legal. If this happens, it brings up a major issue regardless of the WCA's decision:
If the results are accepted, there would be a ton of community backlash (just look at the reaction to the 3.47 which was a perfectly legitimate scramble).
If, on the other hand, the WCA decides to DNF/use extras instead, then 2-move scrambles are not actually legal, and the regulations should not be written to imply such.
On one hand, I think this is a legitimate concern. The only correct procedure by the current regulations would be to keep a 2-move scramble when it happens, but who knows if people will actually follow the regulations?

On the other hand, the community backlash when (or rather, if) this happens would be an extremely good opportunity to reflect on why the community as a whole is so obsessed over singles in a heavily RNG-based sport.

I mean, my personal opinion is that the move count floor should be raised from 2 moves to something like 13 or 14 moves, just to make it more consistent with the faster events that have a floor above 2 moves. That still leaves room for crazy stuff like just a straight up V perm (skipping F2L and OLL altogether), and then we might start arguing over whether optimal move count is really the metric to be filtering by… I don't really have a strong opinion on what the Correct way of handling this is, but I believe dismissing the problem as being too rare to care about (as the WCA has done) is a completely legitimate decision.

Big cubes also pose a computational challenge if you want a "comparable" move filter (i.e. something like 30 moves for 5/6/7/mega); it's just not possible with current hardware to even implement such a move filter and have the running time be measured in seconds rather than months/years/decades/universe-lifetimes. (Remember, people already complain about 4×4×4 random-state scrambles taking forever to generate, and those take only seconds.)

(Edit: also, forgot to mention: apparently introducing move filters was considered controversial back in the day? Getting lucky is not a crime; if (e.g.) a 3-move 222/skewb/pyra/squan scramble is generated, why should that be rejected just for being easy? I think there's something to be said about making sure scrambles don't get too easy so that one can't just grind until they go to a competition that happened to have generated super-easy scrambles, but this is a lot more nuanced than my 5 am brain is willing to think through right now.)
 
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