Aug 13, 2020 07:21
Have a good night. And my name is Naji.
Aug 13, 2020 07:21
Or we can find some other way to chat. I am not sure if this will be available tomorrow, but we can try this as well.
Aug 13, 2020 07:20
Yeah sure. I am on [email protected]
Aug 13, 2020 07:20
Really!
Aug 13, 2020 07:20
Thank you so much for taking the time!
Aug 13, 2020 07:20
Sounds good!
Aug 13, 2020 07:20
Yes in general it can have elemtns and that's why it is called measure zero. I understand. Now I additionally know (based on my reasoning) that 𝜎 = 𝜎' all the time, i.e. for all the omega. Therefore that particular measure zero set we are talking about needs to be empty.
Aug 13, 2020 07:16
No you can't because the set that 𝜎 = 𝜎' + 1 is of measure zero. The only thing that proves is that such a set, i.e. where 𝜎 = 𝜎' + 1 holds is exactly the empty set.
Aug 13, 2020 07:11
Or better said \Omega
Aug 13, 2020 07:11
Holding for a single omega is enough to ensure it holds all the time, because sigma and sigma' are not relevant to omega.
Aug 13, 2020 07:09
No you cant is in that case that set would be of measure 1! because then it should hold for any omega with the same reasoning but we know the other set is of measure zero!
Aug 13, 2020 07:06
Does it really matter? Write the error term. I am saying that there is one such omega where the equality holds. It should therefore hold for any omega because sigma and sigma' do not depend on omega any way!
Aug 13, 2020 07:04
𝜎 and 𝜎' are cosntant independent of the sample space
Aug 13, 2020 07:03
But 𝜎 and 𝜎' are constant. So if it holds for one omega it needs to hodl all the time.
Aug 13, 2020 07:03
right?
Aug 13, 2020 07:03
So we agree that there is a πœ” where this holds
Aug 13, 2020 07:01
what does this mean "𝜎 = 𝜎' a.s."?
Aug 13, 2020 07:01
Then it follows that 𝜎 = 𝜎'
Aug 13, 2020 07:00
well 𝜎 = 𝜎' a.s. as you say. Take one πœ” that this holds. It is measure 1 right?
Aug 13, 2020 06:59
It is in my case.
Aug 13, 2020 06:59
S-S' is not constant in what you're implying
Aug 13, 2020 06:58
Exactly because they're constant I am only willing to take one such πœ”. Nothing at this point depends on πœ”.
Aug 13, 2020 06:56
What I am saying is that
N log(𝜎) + N/(2𝜎^2) S = N log(𝜎') + N/(2𝜎'^2) S' is valid for all 𝜔
Therefore
1/(2𝜎^2) S - 1/(2𝜎'^2) S'=log(𝜎') - log(𝜎) is valid for all 𝜔
Now the left hand side almost surely goes to 𝜎 - 𝜎'. Take one such 𝜔 that equality holds. Then the result follows.
Aug 13, 2020 06:48
It is not but it is actually equal to \log(\sigma)-\log(sigma') which is still fine
Aug 13, 2020 06:47
Yes, but I am summing those sequences basically to cancel out S and S' because I can!
Aug 13, 2020 06:46
𝑃{lim𝑋𝑛=𝜎2}=1 and 𝑃{limπ‘Œπ‘›=πœŽβ€²2}=1. But additionally I know 𝑋𝑛=π‘Œπ‘› and that's where I can do everything before the final value of the limit is realized to free up myself from dependence on πœ”.
Aug 13, 2020 06:44
lol ok
Aug 13, 2020 06:43
how are you writing in latex?
Aug 13, 2020 06:43
No no, hold on
Aug 13, 2020 06:42
Yes the way I wrote it is meaningless, and quite handwavy, but I think I can formalize it. I know your phd is in math and my bachelors is in math, so I have a lot to catch up on formalism. But either way may argument all happens before the final limit is approached.
Aug 13, 2020 06:35
It is where I say Writing above limits in πœ–/𝛿 form (sum lhs of both and rhs of both) we can get
Aug 13, 2020 06:34
lol, I just copied an pasted from the original comment
Aug 13, 2020 06:33
Does that make sense to you or should I explain how I get that?
Aug 13, 2020 06:33
No no, I am talking about how I get from your equation above to 𝑃{πœ”:|πœŽβˆ’πœŽβ€²|>πœ–}→0
Aug 13, 2020 06:32
That's not the part that I am applying things. When I have things in paranthesis and I am calculating limits, I use triangle inequality to get rid of anything dependant on $N$ does it make sense until that part?
Aug 13, 2020 06:30
(Why LaTeX is not parsed here?? :|)
Aug 13, 2020 06:29
As you said yourself!
Aug 13, 2020 06:29
I am talking my particualr example. Indeed for any omega I have:
$$N \log(\sigma) + \frac{1}{2\sigma^2} \sum_{i=1}^N (X_i (\omega) - \mu)^2 & = N \log(\sigma') + \frac{1}{2\sigma'^2} \sum_{i=1}^N (Y_i (\omega) - \mu')^2 \\
N \log(\sigma) + \frac{N}{2\sigma^2} \left(\frac{1}{N}\right) \sum_{i=1}^N (X_i (\omega) - \mu)^2 & = N \log(\sigma') + \frac{N}{2\sigma'^2} \left(\frac{1}{N}\right) \sum_{i=1}^N (Y_i (\omega) - \mu')^2$$
Aug 13, 2020 06:28
So I understand your example. I just don't think my reasoning suffers from this counterexample. It drops N at some point of reasoning, as there is no $N$ involved.
Aug 13, 2020 06:27
And in that sense I can get rid of $N$ in the final limiting relationship I have.
Aug 13, 2020 06:27
Yes but the point is that in my case I know for every $n$ and for any $\omega$ the said equality holds!
Aug 13, 2020 06:25
Let me process what you wrote.
Aug 13, 2020 06:25
No problem! Thanks for being so active in open source community and helping people!
Aug 13, 2020 06:24
I'll let you write until you say you're done. Btw we can also zoom or something. I am the same person who wrote about your CV and the website HTTPS issue.
Aug 13, 2020 06:23
And I clarified this with the last proof by contradiction I implied.
Aug 13, 2020 06:23
I just disagree in this case one cannot make such a conclusion
Aug 13, 2020 06:22
Believe it or not I know the definitions of convergence in probability, in distribution and a.s.
Aug 13, 2020 06:22
I wrote $\sigma-\sigma'$ not $\omega-\omega'$. If I did then I made a typo.
Aug 13, 2020 06:21
Hello! I wasn't expecting you to be awake! Thanks for taking the time to address this!
Aug 13, 2020 06:17
That's my bad and I agree with you, but I don't get what you mean by " If the the π‘Œπ‘–(πœ”) "do something normal" that leads to that sample variance converging to $\sigma'^2$, then we have a value of πœ” where the sample variances are equal even in the limit, and don't cancel out. ". Either way, I stil think the reasoning I made 6 comments ago stands. The summation I presented there literally implies $$P\{\omega:|\sum(X_n(\omega)-\mu)^2 - \sum(X_n'(\omega)-\mu')^2+\sigma-\sigma'|>\epsilon\}=P\{\omega:|\sigma-\sigma'|>\epsilon\}\to 0 .$$ In fact let's assume that's not the case...