Abstract
Recent results in geometric invariant theory (GIT) for non-reductive linear algebraic group actions allow us to stratify quotient stacks of the form [X∕H], where X is a projective scheme and H is a linear algebraic group with internally graded unipotent radical acting linearly on X, in such a way that each stratum [S∕H] has a geometric quotient S∕H. This leads to stratifications of moduli stacks (for example, sheaves over a projective scheme) such that each stratum has a coarse moduli space.
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References
J. Alper, Good moduli spaces for Artin stacks. Ann. Inst. Fourier (Grenoble) 63(6), 2349–2402 (2013)
G. Bérczi, F. Kirwan, Graded unipotent groups and Grosshans theory. Forum Math. Sigma 5, 21–45 (2017)
G. Bérczi, B. Doran, T. Hawes, F. Kirwan, Constructing quotients of algebraic varieties by linear algebraic group actions, in Handbook of Group Actions, ed. by L. Ji, A. Papadopoulos, S.-T. Yau. Advanced Lectures in Mathematics (ALM), vol. 4 (Higher Education Press and International Press, to appear). arXiv:1512.02997
G. Bérczi, B. Doran, T. Hawes, F. Kirwan, Geometric invariant theory for graded unipotent groups and applications. J. Topology (to appear). arXiv: 1601.00340
G. Bérczi, B. Doran, F. Kirwan, Graded linearisations, in Modern Geometry—A Celebration of the Work of Simon Donaldson, ed. by V. Munoz, I. Smith, R. Thomas. AMS Proceedings of Symposia in Pure Mathematics (to appear). arXiv:1703.05226
G. Bérczi, B. Doran, T. Hawes, F. Kirwan, Projective completions of graded unipotent quotients. arXiv:1607.04181
G. Bérczi, V. Hoskins, F. Kirwan, Quotients of unstable subvarieties and moduli spaces of sheaves of fixed Harder–Narasimhan type II (in preparation)
D.A. Cox, The homogeneous coordinate ring of a toric variety. J. Algebraic Geometry 4, 17–50 (1995)
I. Dolgachev, Y. Hu, Variation of geometric invariant theory quotients. Inst. Hautes Études Sci. Publ. Math. 87(1), 5–56 (1998)
B. Doran, F. Kirwan, Towards non-reductive geometric invariant theory. Pure Appl. Math. Q. 3, 61–105 (2007)
D. Edidin, D. Rydh, Canonical reduction of stabilizers for Artin stacks with good moduli spaces. arXiv: 1710.03220
D. Halpern-Leistner, Theta-stratifications, theta-reductive stacks, and applications, in Proceedings of the 2015 AMS Summer Institute in Salt Lake City (to appear)
G. Harder, N.S. Narasimhan, On the cohomology groups of moduli spaces of vector bundles on curves. Math. Ann. 212(3), 215–248 (1975)
W.H. Hesselink, Uniform instability in reductive groups. J. Reine Angew. Math. 304, 299–316 (1978)
V. Hoskins, Stratifications for moduli of sheaves and moduli of quiver representations. J. Algebraic Geometry (to appear). arXiv: 1407.4057
V. Hoskins, F. Kirwan, Quotients of unstable subvarieties and moduli spaces of sheaves of fixed Harder–Narasimhan type. Proc. London Math. Soc. 105(4), 852–890 (2012)
J. Jackson, Oxford DPhil thesis (2018)
G. Kempf, Instability in invariant theory. Ann. Math. 108(2), 299–316 (1978)
F. Kirwan, Cohomology of quotients in symplectic and algebraic geometry. Mathematical Notes, vol. 31 (Princeton University Press, Princeton, 1984)
F. Kirwan, Partial desingularisations of quotients of nonsingular varieties and their Betti numbers. Ann. Math. 122(1) 41–85 (1985)
F. Kirwan, Refinements of the Morse stratification of the normsquare of the moment map, in the breadth of symplectic and Poisson geometry. Progr. Math. 232, 327–362 (2005)
D. Mumford, J. Fogarty, F. Kirwan, Geometric Invariant Theory, 3rd edn. (Springer, New York, 1994)
L. Ness, A stratification of the null cone via the moment map. Am. J. Math. 106,1281–1329 (1984)
P.E. Newstead, Introduction to moduli problems and orbit spaces. Tata Institute Lecture Notes (Springer, New York, 1978)
D. Rydh, Existence and properties of geometric quotients. J. Algebraic Geometry 22(4), 629–669 (2013)
S. Shatz, The decomposition and specialization of algebraic families of vector bundles. Compos. Math. 35, 163–187 (1977)
C. Simpson, Moduli of representations of the fundamental group of a smooth projective variety. Publications Mathématiques de l’IHÉS 79(1), 47–129 (1994)
M. Thaddeus, Geometric invariant theory and flips. J. Am. Math. Soc. 9(3), 691–723 (1996)
Acknowledgment
V.H. is supported by the Excellence Initiative of the DFG at the Freie Universität Berlin.
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Bérczi, G., Hoskins, V., Kirwan, F. (2018). Stratifying Quotient Stacks and Moduli Stacks. In: Christophersen, J., Ranestad, K. (eds) Geometry of Moduli. Abelsymposium 2017. Abel Symposia, vol 14. Springer, Cham. https://doi.org/10.1007/978-3-319-94881-2_1
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