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Martin Brandenburg's user avatar
Martin Brandenburg's user avatar
Martin Brandenburg's user avatar
Martin Brandenburg
  • Member for 13 years, 3 months
  • Last seen more than a month ago
  • 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
answer
285
Examples of common false beliefs in mathematics
May 5, 2010
question
102
A proof for $\dim(R[T])=\dim(R)+1$ without prime ideals?
Jun 21, 2014
question
91
$A$ is isomorphic to $A \oplus \mathbb{Z}^2$, but not to $A \oplus \mathbb{Z}$
Sep 12, 2015
question
87
When is $A$ isomorphic to $A^3$?
Dec 30, 2009
question
75
Rigidity of the category of schemes
Feb 28, 2011
question
74
$R$ is isomorphic to $R[X,Y]$, but not to $R[X]$
Dec 11, 2015
answer
71
What are the reasons for considering rings without identity?
Apr 26, 2010
answer
68
Example of an unnatural isomorphism
Aug 14, 2013
question
65
explicit big linearly independent sets
May 1, 2010
question
63
Results from abstract algebra which look wrong (but are true)
Jan 19
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ChatGPT strikes MathOverflow
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A proof for $\dim(R[T])=\dim(R)+1$ without prime ideals?
172
Nice examples of groups which are not obviously groups
146
If $AB = I$ then $BA = I$
105
Ring structure on the Galois group of a finite field
70
Order of a product of subgroups. Prove that $o(HK) = \frac{o(H)o(K)}{o(H \cap K)}$.

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