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An expert is a man who has made all the mistakes, which can be made, in a very narrow field. (Niels Bohr)


Sep
13
comment The problem of the most visited point.
@Teepeemm No, no solution was found.
Aug
19
comment $ d(x,y)^2 \le d(x,z)^2 - d(y,z)^2\color{}{+\varphi\big(x,y,z,d(x,y),d(y,z) \big)}? $
@900sit-upsaday Thanks for your help. However this article from the article link is not what I seek. I did not know this article. Hopefully he quotes the article or article that is cited by the try. Your information has been very helpful.
Aug
9
comment How can we calculate $(x^x)'$
@AndersKaseorg The recurrence is correct. Both my and yours. Think about the cases $n = 2$ and $n = 3$. What can you say?
Jul
24
comment Banach Fixed Point Theorem. Measurable version.
@Ilya Sorry about the absence. But I have to go now. I'll think about it.
Jul
24
comment Banach Fixed Point Theorem. Measurable version.
@PhoemueX, $L$ is a fixed constant. I add it now.
Jul
24
comment Banach Fixed Point Theorem. Measurable version.
@Ilya Yes, the statement is valid for dirac measure or perturbation of the Dirac measure. I'm still thinking about it.
Jul
24
comment Banach Fixed Point Theorem. Measurable version.
@Ilya My mistake, I forgot to put the hypothesis of continuity. With hiótese the existence of continuity follows easily from other fixed point theorems. I'll add the hypothesis of the continuity issue. My interest is in the uniqueness of the fixed point.
May
13
comment Computing the Frechet derivative of the inverse endomorphism.
@user115608 Look on Wikipedia for Neumann series.Use the link of answer!
Apr
24
comment Intuition on Wald's equation without using the optional stopping theorem.
@Did The English language is not my native language. I understood the expression 'rather moot' as meaning 'debatable'. But it can also be understood as 'irrelevant'.
Apr
24
comment Intuition on Wald's equation without using the optional stopping theorem.
@Did, could you explain me better what becomes the debatable point in wald's equation?
Apr
20
comment What should one do if one works on a problem and submits a paper only to find that it is already in some book?
@MathAM You could paper to write a review if the path you took if your work is essentially different from the work done in the book.
Apr
19
comment Proving $\int_{0}^{\infty} \mathrm{e}^{-x^2} dx = \dfrac{\sqrt \pi}{2}$
Yocks. This method exploits the asymptotic behavior of exponential functions in a surprising way!
Apr
5
comment showing $Q[\sqrt 2] = Q(\sqrt 2)$
Hi Joe. Forgive my possible ignorance. But the statement " Before all is clear que $ \mathbb{Q}[\sqrt{2}] \subseteq \mathbb{Q}(\sqrt{2})$ " is not at all clear.
Mar
21
comment Prove that $\mu(a, b)= \mu(1, b/a)$.
Also add the reference (and the relevant page) this exercise. That way, members of the MSE help you.
Mar
11
comment Inexact Newton method.
@LutzL I know the Newton-Kantorovich theorem and its several versions. The point is that this question calls for a robust version of the Kantorovich theorem. And not only robust robust locally but globally robust.
Feb
4
comment Growth Rate. A precise definition.
OK. Recently I realized that his point of view refers to something we can call "discrete derivative". Could you explain your point of view? An example? I thank you.
Jan
28
comment Suppose G has order 4, but contains no element of order 4. A) prove that no element of G has order 3.?
This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post - you can always comment on your own posts, and once you have sufficient reputation you will be able to comment on any post.
Jan
25
comment how to find $ \lim\limits_{x \to \infty} \left(\sqrt{x^2 +1} +\sqrt{4x^2 + 1} - \sqrt{9x^2 + 1}\right)$
Very nice this trick!
Jan
14
comment Proof that $x^k < k^x$
@Setzer22 yes, $\log_{\,k} k=1$.
Jan
7
comment Growth Rate. A precise definition.
Thanks and +1. After a while I discovered that the answer given by the source of this problem is 20.050 copies