Alyosha
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 Mar23 comment Dirac delta implies continuous? @Woodface I don't have a rigorous one. Mar20 comment Show that there are only finitely many subgroups of $F$ in which $H$ can be of finite index. $F$ is free on how many generators? Mar20 comment Simple proof verification What does $\Gamma_i$ mean? Mar15 comment Badly behaved, but easy-to-manipulate examples of rings to test hypotheses on @N.H. Oh, thanks! Maybe you could answer with an example if you have the time? Mar12 comment 'Elementary' proof of $\tilde{X}$ is contractible iff $\pi_n(X) =0 \forall n \ge 2$. Sorry, why does it follow that $\pi_1(X)= \pi_1(\tilde{X})$ for $n \ge 2$? Mar10 comment If $S_\epsilon$ is dense for all $\epsilon$, is $S_0$ dense? The italics are directed not at anyone who has already answered, but at potential answerers. Mar9 comment Discriminant is the unique invariant of $\text{SL}_2\mathbb{Z}$ acting on polynomials. Leox, this answer is actively detrimental to my attempts to understand this, in that having an answer reduces answerer-traffic, and this answer is basically a rephrasing of the question with the addition of 'some theorem proves it'. Please either delete this or at least provide a link to the proof of that result (I can't find a proof by googling). Thank you. Mar9 comment If $S_\epsilon$ is dense for all $\epsilon$, is $S_0$ dense? Baire, measures or whatever are fine to use, this isn't a homework, but I doubt they will be that useful here, even if it feels a little Bairey. Mar7 comment Is the pushforward measure a categorical-theoretic pushout? @tomasz I just guessed about it being a pushout, what I really wanted to know was whether it is universal in some category. Could you consider fleshing out your description of how pushforward maps are universal into an answer? Feb13 comment 'Elementary' proof of $\tilde{X}$ is contractible iff $\pi_n(X) =0 \forall n \ge 2$. @KevinCarlson Thank you, I will edit. Feb13 comment 'Elementary' proof of $\tilde{X}$ is contractible iff $\pi_n(X) =0 \forall n \ge 2$. @NajibIdrissi Yes. Jan28 comment Conservation of bilinear forms and conjugation @OlivierBégassat Could you clarify what the matrix of a bilinear form is? Jan27 comment Conservation of bilinear forms and conjugation @OlivierBégassat Yes. Jan27 comment Conservation of bilinear forms and conjugation @OlivierBégassat Thanks, it was $\Bbb{C}$. Jan13 comment Groups with no nontrivial topology @PedroTamaroff Thanks, these are the sort of things I really appreciate in trying to work out how to intuit the topologisation of groups. Jan13 comment Groups with no nontrivial topology @NajibIdrissi Okay, edited. Jan7 comment Which $n$th order differential equations have $n$ linearly independent solutions? @user1537366 No, I didn't. Dec28 comment Is there a general way to prove series and products are modular? @guest Thanks, edited. Dec25 comment Motivation for constructing $F$ s.t. $\ker(\text{curl}) \subset \text{Im}(\text{grad})$, $\ker(\text{div}) \subset \text{Im}(\text{curl})$ Thanks for the thorough answer, and sorry for not replying sooner. The answer has helped understand the theory more, but I still feel confused as to how the author came up with $F(x_1,x_2)$ and $G(x,t)$ in the first line of each proof, their use seems a little magical to me still. Dec24 comment Motivation for constructing $F$ s.t. $\ker(\text{curl}) \subset \text{Im}(\text{grad})$, $\ker(\text{div}) \subset \text{Im}(\text{curl})$ @Travis I don't.