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_\...
Dan Petersen's user avatar
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