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Jun 7 at 14:15 history edited LSpice CC BY-SA 4.0
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Jun 7 at 0:55 history edited David Roberts CC BY-SA 4.0
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Jun 6 at 23:09 history edited zeta CC BY-SA 4.0
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May 19 at 9:13 comment added Leo Hi, I think your fiber sequence is wrong. It should be $B^3\mathbb{Z}\to B String(n)\to B Spin(n)\to B^4\mathbb{Z}$. The loop space appears to the left, not to the right. One good way to understand $String(n)$ is to view it as a smooth 2-group.
Nov 24, 2023 at 13:37 comment added Konrad Waldorf There exists a model for the classifying space $BG$ of a topological group $G$, such that when $G$ is abelian, $BG$ is again an abelian group. This is Segal's construction, namely, the geometric realization of the groupoid with a single object with automorphism group $G$. The same is true for $EG$.
Nov 24, 2023 at 13:16 answer added Konrad Waldorf timeline score: 5
Nov 24, 2023 at 8:57 comment added Sebastian Goette The projective unitary group $PU$ of a separable Hilbert space is weakly(?) homotopy equivalent to $\mathbb CP^\infty$. It is not abelian.
Nov 23, 2023 at 18:55 history edited Dmitri Pavlov CC BY-SA 4.0
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Nov 23, 2023 at 18:52 answer added Dmitri Pavlov timeline score: 3
Nov 23, 2023 at 16:10 history asked zeta CC BY-SA 4.0