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I'm a student of mathematics in Germany.


Jan
13
comment In $\Bbb Z$, what element generates the ideal $(4,7)$?
(@SydKerckhove In German it’s “Hauptidealring” (HIR), though.)
Jan
13
comment In $\Bbb Z$, what element generates the ideal $(4,7)$?
“Hauptideal domain”. Why do I love this so much?
Jan
12
comment What is $0^{i}$?
@hjhjhj57 Well, you should make the value of your answer visible in your answer. So far, all the value is in alex.jordan’s comment. You should include in your answer that this is a (very) weak argument and explain why.
Jan
12
comment What is $0^{i}$?
I downvoted for the very reason that alex.jordan already pointed out.
Jan
11
comment Schwarz reflection over $S(0,1)$
@user101521 Yeah, that’s the idea. Well, it sounds like you need to figure out a formal statement for the reflection principle for the circle and then prove it. For this, you can proceed like you said.
Jan
11
comment Schwarz reflection over $S(0,1)$
@user101521 Kind of. The preimage of the unit circle under $\exp$ is $iℝ$ (not a rectangle, you probably were thinking of the preimage of the unit disk). For $f\colon D → ℂ$, you can check $f ∘ \exp$ on $f^{-1}(D)$ for the conditions of the Schwarz reflections principle. You just need to figure out what you can do with this.
Jan
11
answered Schwarz reflection over $S(0,1)$
Jan
11
revised The pushout of an open/closed injective map is open/closed
added 24 characters in body
Jan
11
revised The pushout of an open/closed injective map is open/closed
added 6 characters in body
Jan
11
revised The pushout of an open/closed injective map is open/closed
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Jan
11
answered The pushout of an open/closed injective map is open/closed
Jan
11
revised Eilenberg–Steenrod axioms for homology without pairs of spaces
edited body
Jan
10
comment Proof that a sequence is bounded.
For all $n ∈ ℕ$, $|a_n| = n$? To prove things, it is very helpful to define them in a rigorous manner. Define $a_n = …$
Jan
10
revised Application of the mean value theorem to find $\lim_{n\to\infty} n(1 - \cos(1/n))$
edited tags
Jan
10
answered Application of the mean value theorem to find $\lim_{n\to\infty} n(1 - \cos(1/n))$
Jan
10
comment Can we take a tensor product of algebra and module?
Have a look at scalar extensions, maybe you will find there what you are looking for.
Jan
10
comment Intermediate fields of $X^p - 2 $
What is $\{1\}'$?
Jan
10
comment Proving this function is an open map
@hallaplay835 My answer still applies: Check what I wrote in parantheses.
Jan
10
revised Proving this function is an open map
added 4 characters in body
Jan
10
answered Proving this function is an open map