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Timeline for Is this exact sequence known?

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Jan 9, 2023 at 12:21 comment added Pedro @MikhailBorovoi Perhaps the "direct check" is reproducing the proof of the Snake Lemma?
Jan 9, 2023 at 2:24 history edited LSpice CC BY-SA 4.0
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Oct 21, 2022 at 11:38 answer added Mikhail Borovoi timeline score: 4
Sep 4, 2022 at 18:28 vote accept Mikhail Borovoi
Sep 4, 2022 at 18:13 vote accept Mikhail Borovoi
Sep 4, 2022 at 18:14
Sep 4, 2022 at 17:56 answer added SashaP timeline score: 5
Sep 4, 2022 at 17:12 history edited Mikhail Borovoi CC BY-SA 4.0
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Sep 4, 2022 at 17:00 comment added Mikhail Borovoi @SashaP: The answer that I have is by direct checks on cocycles (four pages of calculations). The preprint will appear in arXiv on Wednesday September 7, and I have enough time to replace my direct checks by your nice proof.
Sep 4, 2022 at 16:56 comment added Mikhail Borovoi @SashaP: Yes, this is exactly the kind of answer I am looking for. Please kindly post an answer with as much details as possible!
Sep 4, 2022 at 16:26 comment added SashaP On the other hand, the six groups appearing in the desired sequence appear on the 1st page of this spectral sequence and, since both $Tor_0(H_1(\Gamma,M_3),\mathbb{Q}/\mathbb{Z})$ and $Tor_0(H_1(\Gamma,M_2),\mathbb{Q}/\mathbb{Z})$ are zero (because these homology groups are annihilated by the order of $\Gamma$), no non-zero differentials on page 2 and onward can touch these 6 groups, which gives the desired sequence.
Sep 4, 2022 at 16:26 comment added SashaP I'm not sure if this is a kind of answer that you're looking for or if I'm repeating the proof you already have, possibly in a different language. We can get this exact sequence from the spectral sequence corresponding to the derived functor of tensor product with $\mathbb{Q}/\mathbb{Z}$ applied to the long exact sequence of $\Gamma$-homology corresponding to the given SES. On the one hand this long exact sequence is an acyclic complex so the spectral sequence must converge to zero.
Sep 4, 2022 at 15:42 history edited Mikhail Borovoi CC BY-SA 4.0
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Sep 4, 2022 at 14:14 history edited Mikhail Borovoi CC BY-SA 4.0
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Sep 4, 2022 at 13:46 history asked Mikhail Borovoi CC BY-SA 4.0