Mathematics
Martin Brandenburg's user avatar
Martin Brandenburg's user avatar
Martin Brandenburg's user avatar
Martin Brandenburg
  • Member for 13 years
  • Last seen this week
  • Berlin, Germany
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About

I'm doing software development now, which is why my activity on mathoverflow and mathematics has become quite irregular. So probably I won't see your questions on my old answers, sorry for that.

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All Questions Answers
Score Newest
question
816
A proof for $\dim(R[T])=\dim(R)+1$ without prime ideals?
Apr 11, 2013
answer
174
Nice examples of groups which are not obviously groups
Apr 15, 2013
answer
149
If $AB = I$ then $BA = I$
Sep 2, 2010
question
109
Ring structure on the Galois group of a finite field
Nov 17, 2013
answer
74
Order of a product of subgroups. Prove that $o(HK) = \frac{o(H)o(K)}{o(H \cap K)}$.
Jul 10, 2012
question
69
Geometric intuition for the tensor product of vector spaces
Sep 6, 2013
answer
62
A non-noetherian ring with noetherian spectrum
Oct 21, 2010
question
60
Surprisingly elementary and direct proofs
May 28, 2013
answer
58
Submodule of free module over a p.i.d. is free even when the module is not finitely generated?
Jun 25, 2012
answer
57
Proving that $\mathbb{Z}[x]$ and $\mathbb{Q}[x]$ are not isomorphic.
May 5, 2013
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290
Examples of common false beliefs in mathematics
103
A proof for $\dim(R[T])=\dim(R)+1$ without prime ideals?
91
$A$ is isomorphic to $A \oplus \mathbb{Z}^2$, but not to $A \oplus \mathbb{Z}$
87
When is $A$ isomorphic to $A^3$?
76
Rigidity of the category of schemes

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