4
votes
Does anyone have a good example of an injective resolution?
It is a well-known fact that the category of abelian groups has enough injectives, hence actually any abelian group has an injective resolution. Furthermore, the global dimension of the ring $\mathbb{...
- 141
3
votes
Accepted
(Derived category of) sheaves over an infinite union
An easier argument would be that $R^q\pi_\ast \mathbf Q$ vanishes for $q\notin \{0,3\}$ and has rank $1$ for $q \in \{0,3\}$. Indeed, just check this on stalks. Then the cone of $\mathbf Q\to R\pi_\...
- 39.3k
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