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Dec 18, 2020 at 9:31 comment added Dustin Clausen Yes, Yemon. I don't know what it's called, but that's what it is.
Dec 17, 2020 at 21:48 comment added Yemon Choi @DustinClausen Is this what "homological cavemen" like myself might call hyper(co)homology? i.e. take a projective resolution of each $P_i$ and then take the (co)homology of the total complex?
Dec 17, 2020 at 21:07 comment added Dustin Clausen You can also think of it like this. If it were a projective resolution, we could use it to calculate $Ext^i(\mathbb{R},A)$ in terms of $Hom(P_i,A)$. The spectral sequence is saying that even when the terms are not projective, you can still in some sense calculate $Ext^i(\mathbb{R},A)$ in terms of not just $Hom(P_i,A)$, but $RHom(P_i,A)$. I think this plus the special case where there are only 2 terms mentioned above give the "feel" for this sort of thing.
Dec 17, 2020 at 21:06 history edited Sofía Marlasca Aparicio CC BY-SA 4.0
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Dec 17, 2020 at 21:02 comment added Dustin Clausen Exactly, he means the spectral sequence for $Ext^i(-,A)$ coming from the "stupid" filtration on the resolution (without the $\mathbb{R}$ term) induced by truncation. If there were only two terms in the resolution, this would be the same as the induced long exact sequence on $Ext^i(-,A)$.
Dec 17, 2020 at 20:49 review First posts
Dec 18, 2020 at 4:46
Dec 17, 2020 at 20:42 history asked Sofía Marlasca Aparicio CC BY-SA 4.0