Probability Thread

[tseitsei]

ftfy

Ok. Then please enlighten me why random state scramble wouldn't be completely random?

 

[Stefan]

Ok. Then please enlighten me why random state scramble wouldn't be completely random?

Huh? Who said that?

 

[tseitsei]

Huh? Who said that?

Well I gave him a link that explains what we consider random scrambles and you said that I googled something totally different...

 

[Robert-Y]

What's the probability that I get a specific case a specific number of times in a row for a specific number of solves?!

To me it seems that recently some people in this thread have not realized that their questions are actually very oddly specific. Most of these occurrences do not seem very significant or interesting to me at all...

EDIT: Oops. Nevermind, it's just 2 "recent" requests actually...

 

[Stefan]

Well I gave him a link that explains what we consider random scrambles and you said that I googled something totally different...

No you claimed to have googled "that", but the talk was about "random scramble" and you instead googled "random state scramble". That's not the same, it's something else. Which is what I said. And in fact, if you take out the word "state" that you added, the first result (at least for me) about cubing is *not* using random state scrambles but random turns.

 

[tseitsei]

No you claimed to have googled "that", but the talk was about "random scramble" and you instead googled "random state scramble". That's not the same, it's something else. Which is what I said. And in fact, if you take out the word "state" that you added, the first result (at least for me) about cubing is *not* using random state scrambles but random turns.

Using random moves isn't really what (most of the) speedcubers consider being random scrambles...

But yeah I see what you mean now.

 

[cmhardw]

What's the probability that I get a specific case a specific number of times in a row for a specific number of solves?!

To me it seems that recently some people in this thread have not realized that their questions are actually very oddly specific. Most of these occurrences do not seem very significant or interesting to me at all...

EDIT: Oops. Nevermind, it's just 2 "recent" requests actually...

I agree that people often ask extraordinarily specific questions when they probably mean a much more general question without realizing.

 

[obelisk477]

I agree that people often ask extraordinarily specific questions when they probably mean a much more general question without realizing.

I think I'm gonna start responding to this thread only using equivalent probabilities. "What's the odds of getting a U-perm 4 times in a row!?!?!!11?" "Same as the odds of U perm, then an R perm, then a J perm, then an A perm"

 

[cmhardw]

Probability of an Xcross on 4x4 after edge paring using Yau?

The probability of at least one solved corner edge pair in the F2L after edge pairing, and using Yau, is about 0.01

Clicky

--edit--

Apparently the old way I used to type sums into Wolfram Alpha does not work well anymore. I rewrote the wolfram alpha link using their help files. The link should work now.

--edit 2--

Ugh... I have to include the division by the total number of cases in the summation itself to get it to work properly :\ I'm not a fan of this, but I think the link should finally work.

 

[TMOY]

Probability of an Xcross on 4x4 after edge paring using Yau?

Pleae give a proper definition of "Xcross after edge pairing" or else it's impossible to answer your question. Which pieces have to be where after edge pairing ?
And yes, I know what an Xcross is.

 

[guysensei1]

What's the probability of getting the same OLL and PLL case (but not necessarily from the same angle!) on consecutive solves?

 

[obelisk477]

What's the probability of getting the same OLL and PLL case (but not necessarily from the same angle!) on consecutive solves?

Depends on the OLL/PLL?

 

[guysensei1]

Depends on the OLL/PLL?

The average probability?


Also I was referring to getting both at once, not as separate events. Am I making sense?

 

[obelisk477]

The average probability?


Also I was referring to getting both at once, not as separate events. Am I making sense?

Well the first OLL/PLL pair is given, so the probability is 1 for it. The probability that any given OLL/PLL 'pair' is then followed by the same 'pair' is 1*(1/58)*(1/22) (if you include skips as possibilities for OLL/PLL) = 1/1276 = .0784%

 

[Stefan]

Well the first OLL/PLL pair is given, so the probability is 1 for it. The probability that any given OLL/PLL 'pair' is then followed by the same 'pair' is 1*(1/58)*(1/22) (if you include skips as possibilities for OLL/PLL) = 1/1276 = .0784%

Not all OLL cases have the same probability. And not even a single one has probability 1/58. Same for PLL.

Imagine one of the OLLs had probability 0.5, and one of the PLLs as well. You'd still say 1/1276, but even just the probability of getting this particular OLL/PLL combination twice in two attempts is already 1/16.

 

[obelisk477]

Not all OLL cases have the same probability. And not even a single one has probability 1/58.

Same for PLL.

He said average probability. The average is just 1/#ofcases right? 57+skip and 21+skip

EDIT: Yes those that would be true for a particular OLL and PLL. But the way I understood the question, he meant an overall average for all OLLs and PLLs in general.

 

[Stefan]

He said average probability.

Just because you had trouble understanding the perfectly fine original question. I don't think he intended to change the meaning.

The average is just 1/#ofcases right? 57+skip and 21+skip

Well, yeah, but I don't think that's interesting. And it certainly doesn't answer the question for the probability of getting the same OLL/PLL twice in a row.

Also, while the average probability for each such OLL case is 1/58, I'm not sure the average such repetition probability is. And I'm too tired to think about it now it's 6:09am I'm going to bed I don't even feel like using commas anymore

 

[obelisk477]

Just because you had trouble understanding the perfectly fine original question. I don't think he intended to change the meaning.

Well, yeah, but I don't think that's interesting. And it certainly doesn't answer the question for the probability of getting the same OLL/PLL twice in a row.

I didn't misunderstand. I asked for the specific OLL/PLL. And would be willing to calculate it if it were provided!

 

[Stefan]

I didn't misunderstand. I asked for the specific OLL/PLL.

Well you said "Depends on the OLL/PLL?", which is wrong (or rather, since you made it a weird question, the answer is "no").

 

[obelisk477]

Well you said "Depends on the OLL/PLL?", which is wrong (or rather, since you made it a weird question, the answer is "no").

It does depend on it, like you mentioned in your eariler example. It's either a specific OLL/PLL combo, or a general one. If the latter, then my answer is correct (1/12xx); if the former, then I was warranted in asking which OLL and PLL he meant. Also, it would help it OP would weigh in...

EDIT: OP's question could also mean 'what are the odds of getting A oll, then B pll, and then A oll again, and then B pll again.' Then the odds are much smaller