Grigory M

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1d
 comment The simplest nontrivial (unstable) integral cohomology operation
@QiaochuYuan I suspect it's something like Jacobi identity. (Notice that the operation is $P(\alpha)=[\alpha,\beta]$ and $d\beta=[\alpha,\alpha]$, where $[-,-]$ is the supercommutator...)
1d
 comment The simplest nontrivial (unstable) integral cohomology operation
(I'm upvoting this, but the question why this operation is nontrivial still remains...)
1d
 comment The simplest nontrivial (unstable) integral cohomology operation
Oh, you're right. (What anti-commutativity actually implies is that the definition doesn't depend on choice of $\beta$.)
1d
 comment The simplest nontrivial (unstable) integral cohomology operation
$\alpha\beta=-\beta\alpha$, so your operation seems to be zero, no?
1d
 revised The simplest nontrivial (unstable) integral cohomology operation
edited tags
2d
 reviewed Close check first isomorphism theorem
2d
 reviewed Leave Open Permutable 2-maximal subgroup and 3-maximal subgroup in special Schmidt group.
2d
 reviewed Leave Open Schmidt group and Permute 2-maximal subgroup with 3-maximal subgroup
2d
 answered Non-orientable 3-manifold has infinite fundamental group
2d
 reviewed Leave Open A separable paracompact space is Lindelof
Jun
15
 answered Hatcher 3.3 Exercise 31
Jun
15
 reviewed Looks Good integration with substitution - why is this so?
Jun
15
 reviewed Close Counting $\#\mathrm{GL}_m(\mathbb{F}_{p^n})$
Jun
15
 reviewed Close $\log$ transform of the fundamental theorem of arithmetic?
Jun
12
 comment Is there a compact contractible manifold?
@Dominik see e.g. Wikipedia or section 3.3 of Hatcher's book
Jun
12
 answered Is there a compact contractible manifold?
Jun
9
 revised How to start learning knot theory?
edited tags
Jun
6
 revised How to compute homotopy classes of maps on the 2-torus?
The previous version of this answer contained serious mistake: it didn't take into account non-triviality of the action of $\pi_1$ on $\pi_2$.
Jun
4
 answered Axiomatizing oriented cobordism
May
31
 comment Riemann Zeta Function and Analytic Continuation
Related: mathoverflow.net/questions/13130/…
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