Timeline for What about stacks of categories in algebraic geometry?
Current License: CC BY-SA 4.0
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| Jun 17 at 5:19 | comment | added | lrg | An additional remark to this answer (since learned this from Drinfeld's paper). Category valued stacks (what Drinfeld calls $c$-stacks) often keep track of "effectivity". For example, sheaves on $B\mathbf{G}_{\mathrm{m}}$, the moduli stack of line bundles (with isomorphisms) are the same as $\mathbf{Z}$-graded abelian groups, while sheaves on $B\mathbf{A}_{\mathrm{m}}^1$, the moduli stack of line bundles (with all maps) are the same as $\mathbf{Z}_{\geq 0}$-graded abelian groups. | |
| Jun 13 at 1:43 | vote | accept | David Roberts♦ | ||
| Jun 13 at 1:39 | history | answered | David Roberts♦ | CC BY-SA 4.0 |