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Results tagged with stacks
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In mathematics a stack or 2-sheaf is a sheaf that takes values in categories rather than sets.
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Does every morphism BG-->BH come from a homomorphism G-->H?
Given a homomorphism f:G→H between smooth algebraic groups, we get an induced homomorphism of algebraic stacks Bf:BG→BH, given by sending a G-torsor P over a scheme X to the H-torsor PxGH, whose (scheme-theoric … Is every morphism of algebraic stacks BG→BH of the form Bf? If not, what is an example of a morphism not of this form? …
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algebraic group G vs. algebraic stack BG
I've gathered that it's "common knowledge" (at least among people who think about such things) that studying a (smooth) algebraic group G, as an algebraic group, is in some sense the same as studying …
CommunityBot
- 1
13
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answer
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Do canonical stacks exist over Spec(Z)?
Theorem 4.6 of Fantechi-Mann-Nironi's Smooth toric DM stacks shows that such stacks have a universal property, so it suffices to show that they exist étale-locally (the universal property ensures the locally … constructed canonical stacks will glue). …
14
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1
answer
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Does a degeneration always have a larger-dimensional automorphism group?
†See Weakly proper moduli stacks of curves by Alper, Smyth, and van der Wyck. …
- 19.6k
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Are root stacks characterized by their divisor multiplicities?
Definitions/Background
Suppose $S$ is a scheme and $D\subseteq S$ is an irreducible effective Cartier divisor. Then $D$ induces a morphism from $S$ to the stack $[\mathbb A^1/\mathbb G_m]$ (a morphis …
- 27k