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Jul
27
revised Is there a unique homomorphism of $\mathbf Z $ into $A$?
english error
Jul
27
comment What would be interesting maps to use on that Eudoxus reals?
I think the interesting question is rather : how do you even represent a rational number using this notion of almost homomorphism? It doesn't seem trivial to guess.
Jul
24
comment Prove that there are infinitely many composite numbers of the form $2^{2^n}+3$.
@user95864 : Yes, that's it!
Jul
23
revised Prove that there are infinitely many composite numbers of the form $2^{2^n}+3$.
added 21 characters in body
Jul
23
answered Prove that there are infinitely many composite numbers of the form $2^{2^n}+3$.
Jul
22
revised The definition of a vector space: closure under scalar multiplication
added 538 characters in body
Jul
22
comment Does $\lim_{x\rightarrow\infty}\frac{d}{dx}f(x)=0$ imply that $\lim_{x\rightarrow\infty}f(x) $ exist?
@JimmyK4542 : We could say $f(x) = \ln(x^2+1)$ to be strictly within OP's context... but this was the correct example to state :) +1
Jul
22
answered The definition of a vector space: closure under scalar multiplication
Jul
21
comment Proving that the coefficients of the characteristic polynomial are the traces of the exterior powers
@caffeinemachine : I couldn't find this material anywhere either, so I just sat down and thought about this. I am pretty happy about this "injection sign" thing, it took me a while to get it right.
Jul
20
comment How can I compute the infimum of the following non linear functional
@Daniel Fischer I'm confused by your comment, isn't a polynomial of degree $0$ a constant? Did you mean $\deg p_n = n$??
Jul
20
comment How can I compute the infimum of the following non linear functional
@user3503589 : if you think in terms of standard linear algebra, putting one linear constraint on a vector gives you an hyperplane, so no, $M$ is not dense. In fact, the zero set of a nonzero continuous linear functional is always a proper closed subspace. You actually need to compute something here, and since the Fourier series computation decomposes over a Hilbert basis consisting of odd and even functions, it should make the task not so hard.
Jul
19
answered How can I compute the infimum of the following non linear functional
Jul
19
comment How can I compute the infimum of the following non linear functional
@user3503589 : I suggest you crop the image so that it only shows the question, just because the rest is irrelevant to the problem.
Jul
19
comment Is there a simple proof of Frobenius's theorem using Sylow theory?
What "Frobenius' Theorem" are you referring to? Frobenius has proved many things.
Jul
16
comment Curve of genus $g$ with a point removed
@user254373 : The MSE way to say thanks is to give the green check. But no problem ;)
Jul
16
comment $H,K$ are normal in $G$, then $HK$ is normal in $G$ (product of normal subgroups is normal)
When you do a major edit (like entirely changing what you are actually asking in the question), you should keep the original question as it is and add "EDIT : insert new stuff here" in the question's text. This way, people that answered the original question don't look weird because they are answering a question you removed by editing.
Jul
15
answered $H,K$ are normal in $G$, then $HK$ is normal in $G$ (product of normal subgroups is normal)
Jul
14
answered Existence of exhaustion by compact sets
Jul
14
revised Curve of genus $g$ with a point removed
added 2 characters in body
Jul
14
answered Curve of genus $g$ with a point removed