Rudy the Reindeer
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 Nov 23 comment Orders of the elements in Z/8Z You're confusing additive and multiplicative notation I suspect. The neutral element here is $0$ not $1$. Nov 23 comment Cauchy Residue Theorem Application Craig, I left a comment in response to your comment to my answer in another thread. Since you probably won't be notified (as you seem to have deleted your comment) I am notifying you here. Nov 23 comment Examples of absolutely continuous functions that are not Lipschitz. @Craig You are right, it's not clear at all, I only hint at how to show uniform continuity. It would have been much better to use Lebesgue integrability of the square root function as in definition (2) here‌​. I will edit the answer when I have time. Thanks a lot for pointing out this shortcoming. Nov 21 comment Continuous function on a compact metric space is uniformly continuous @shilov You should look at the last line of the proof. The inequality should explain it. Nov 20 awarded Nice Question Nov 12 awarded Nice Question Nov 7 revised Reals constructed from equivalence classes of Cauchy sequences of rationals. edited tags Nov 7 revised Upper bound for order of finite group given relations edited tags Nov 6 answered Why $\lim_{x\to \infty} -2xe^{-x/2}$ is $0$? Nov 6 revised Why $\lim_{x\to \infty} -2xe^{-x/2}$ is $0$? edited title Nov 3 comment Fourier transform of the characteristic function @user929304 I see. I don't know if it makes sense, this is beyond my modest knowledge of Fourier transforms. It's not very useful but: Surely the decaying properties of $\mathcal F (\chi_{[c,d]}$ and $\mathcal F (\chi_{[0,1]}$ are almost identical? Nov 3 comment Fourier transform of the characteristic function @user929304 It's not clear to me what you mean. For example, "not differentiable in the usual sense" -- well apart from the points $c,d$ its derivative is 0, or am I missing something? And as for the FT of $\chi_{[c,d]}$: It looks to me like it's decaying. The expression is term one minus term two where each term is of the form one over something exponential times linear. But I might be missing something, it's been a while. Nov 3 comment invertibility in C*-algebra I don't understand why you would try to prove that $a-\lambda$ is invertible if by assumption ($\lambda \in \sigma (a)$) it isn't. What is your question? Nov 3 comment Is it true that $\mathbb{Q}(\sqrt{3},\sqrt{7})=\mathbb{Q}(\sqrt{3},\sqrt{21})$? Nov 2 awarded Nice Question Nov 2 comment Proving $2\mathbb Z$ is maximal ideal of $\mathbb Z$ @RobertoMilandro Yes, exactly. Nov 2 revised Proving $2\mathbb Z$ is maximal ideal of $\mathbb Z$ edited tags Nov 2 answered Proving $2\mathbb Z$ is maximal ideal of $\mathbb Z$ Nov 2 comment Proving $2\mathbb Z$ is maximal ideal of $\mathbb Z$ Regarding your second sentence: It's not possible for any ideal in $\mathbb Z$ to have more elements than $\mathbb Z$. Nov 1 revised Prove that $|S_1\times S_2|=|S_1|\times|S_2|$ edited tags