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Dec
9
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Dec
3
comment What are some important examples of differential objects that aren't naturally graded?
I agree with Qiaochu's comment, however I think that it just hides the indices away in the category $\Delta$ which is defined combinatorially.
Oct
28
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Oct
22
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Oct
18
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Oct
2
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Sep
30
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Sep
24
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Sep
24
comment Quasi-isomorphism from “almost acyclic” complex to its homology
In fact, what does "$X$ is quasi-isomorphic to $Y$" mean?
Sep
8
answered History of category theory
Aug
31
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21
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17
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2
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2
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Jun
20
comment On pushouts and mapping cylinders in exact categories
For the prospective reader, I might add that the easy observation that the forgetful functor from $C\mathcal N$ to the category of graded objects over $\mathcal N$ reflects exactness is implicitly being used.
Jun
17
comment On pushouts and mapping cylinders in exact categories
Great! In fact, not too many days ago I managed to solve the problem with help from my supervisor, and I was planning to post it here very soon. I got the same thing as you though I had to use elements to be convinced that the $P$ you define is effectively the pushout, etc. Thanks a lot for your effort on an already old and quite ignored question.
Jun
17
accepted On pushouts and mapping cylinders in exact categories
Jun
9
accepted Is $\Omega \tilde X \simeq \Omega_0 X$?
May
30
comment Is $\Omega \tilde X \simeq \Omega_0 X$?
Thanks! I'll eagerly read your expanded answer.