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Timeline for Applications of Stacks

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Oct 17, 2010 at 17:15 comment added Qfwfq I haven't met stacks often, but I used to think that they are tautological reformulations of: a) moduli problems b) quotient problems, that allow to "speak geometrically" (e.g. a moduli stack has a tangent bundle, a "moduli problem" doesn't)
Oct 17, 2010 at 1:09 comment added BCnrd Cohomology of stacks provide useful "algebraic/arithmetic" constructions superior in some respects to what can be done using coarse moduli schemes. For example, if one wants to equip spaces of modular forms with $\mathbf{Z}$-structure in a manner that handles all primes in a unified manner, it can be simpler to work with moduli stacks of (generalized) elliptic curves rather than adjoining "extra level" and using fine moduli schemes. For example "$X_0(N)$" is always a regular proper Artin stack, whereas the coarse moduli scheme cousin is neither regular nor fine (but is also useful!).
Oct 16, 2010 at 15:38 answer added Greg Muller timeline score: 10
Oct 16, 2010 at 15:16 answer added user1504 timeline score: 14
Oct 16, 2010 at 14:51 history edited James D. Taylor
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Oct 16, 2010 at 14:29 history asked James D. Taylor CC BY-SA 2.5