Abstract
We explicitly describe infinitesimal deformations of cyclic quotient singularities that satisfy one of the deformation conditions introduced by Wahl, Kollár–Shepherd-Barron (KSB) and Viehweg. The conclusion is that in many cases these three notions are different from each other. In particular, we see that while the KSB and the Viehweg versions of the moduli space of surfaces of general type have the same underlying reduced subscheme, their infinitesimal structures are different.
Funding source: Deutsche Forschungsgemeinschaft
Award Identifier / Grant number: CRC 647
Funding source: National Science Foundation
Award Identifier / Grant number: DMS-1362960
Funding statement: Partial financial support to Klaus Altmann was provided by the DFG via the CRC 647 and to János Kollár by the NSF under grant number DMS-1362960.
Acknowledgements
We would like to thank F.-O. Schreyer for many fruitful discussions and initiating the contact on this topic. Thanks to Jan Stevens for finding mistakes in the originally submitted arXiv version and to the anonymous referee for valuable suggestions.
References
[1] K. Altmann, Minkowski sums and homogeneous deformations of toric varieties, Tohoku Math. J. (2) 47 (1995), no. 2, 151–184. 10.2748/tmj/1178225590Search in Google Scholar
[2] K. Altmann, P-resolutions of cyclic quotients from the toric viewpoint, Singularities. The Brieskorn anniversary volume (Oberwolfach 1996), Progr. Math. 162, Birkhäuser, Basel (1998), 241–250. 10.1007/978-3-0348-8770-0_12Search in Google Scholar
[3] K. Altmann, One parameter families containing three-dimensional toric Gorenstein singularities, Explicit birational geometry of 3-folds, London Math. Soc. Lecture Note Ser. 281, Cambridge University Press, Cambridge (2000), 21–50. 10.1017/CBO9780511758942.002Search in Google Scholar
[4] F. Ambro, Quasi-log varieties, Tr. Mat. Inst. Steklova 240 (2003), 220–239. Search in Google Scholar
[5] E. Brieskorn, Rationale Singularitäten komplexer Flächen, Invent. Math. 4 (1968), 336–358. 10.1007/BF01425318Search in Google Scholar
[6] D. A. Cox, J. B. Little and H. K. Schenck, Toric varieties, American Mathematical Society, Providence 2011. 10.1090/gsm/124Search in Google Scholar
[7] O. Fujino, Introduction to the log minimal model program for log canonical pairs, preprint (2009), https://arxiv.org/abs/0907.1506. Search in Google Scholar
[8] P. Hacking and Y. Prokhorov, Smoothable del Pezzo surfaces with quotient singularities, Compos. Math. 146 (2010), no. 1, 169–192. 10.1112/S0010437X09004370Search in Google Scholar
[9] C. D. Hacon and S. Kovács, Classification of higher-dimensional algebraic varieties, Birkhäuser, Basel 2010. 10.1007/978-3-0346-0290-7Search in Google Scholar
[10]
R. Hartshorne,
Residues and duality. Appendix: Cohomologie à support propre et construction du foncteur
[11] M. Kawakita, Inversion of adjunction on log canonicity, Invent. Math. 167 (2007), no. 1, 129–133. 10.1007/s00222-006-0008-zSearch in Google Scholar
[12] J. Kollár, Flips and abundance for algebraic threefolds (Utah 1991), Astérisque 211, Société Mathématique de France, Paris 1992. Search in Google Scholar
[13] J. Kollár, Flatness criteria, J. Algebra 175 (1995), no. 2, 715–727. 10.1006/jabr.1995.1209Search in Google Scholar
[14] J. Kollár, Hulls and husks, preprint (2008), https://arxiv.org/abs/0805.0576. Search in Google Scholar
[15] J. Kollár, Moduli of varieties of general type, Handbook of moduli. Volume II, Adv. Lect. Math. 25, International Press, Somerville (2013), 131–157. Search in Google Scholar
[16] J. Kollár, Singularities of the minimal model program. With the collaboration of Sándor Kovács, Cambridge University Press, Cambridge 2013. 10.1017/CBO9781139547895Search in Google Scholar
[17] J. Kollár and N. Shepherd-Barron, Threefolds and deformations of surface singularities, Invent. Math. 91 (1988), no. 2, 299–338. 10.1007/BF01389370Search in Google Scholar
[18] D. Mumford, Some footnotes to the work of C. P. Ramanujam, C. P. Ramanujam. A tribute, Stud. Math. 8, Tata Institute of Fundamental Research, Bombay (1978), 247–262. Search in Google Scholar
[19]
H. C. Pinkham,
Deformations of algebraic varieties with
[20] H. C. Pinkham, Deformations of quotient surface singularities (Williamstown 1975), Several complex variables, Proc. Symp. Pure Math. 30. Part 1, American Mathematical Society, Providence (1977), 65–67. 10.1090/pspum/030.1/0447240Search in Google Scholar
[21] O. Riemenschneider, Deformationen von Quotientensingularitäten (nach zyklischen Gruppen), Math. Ann. 209 (1974), 211–248. 10.1007/BF01351850Search in Google Scholar
[22] J. Stevens, Deformations of singularities, Springer, Berlin 2003. 10.1007/b10723Search in Google Scholar
[23] E. Viehweg, Quasi-projective moduli for polarized manifolds, Springer, Berlin 1995. 10.1007/978-3-642-79745-3Search in Google Scholar
[24] J. M. Wahl, Elliptic deformations of minimally elliptic singularities, Math. Ann. 253 (1980), 241–262. 10.1007/BF0322000Search in Google Scholar
[25] J. M. Wahl, Smoothings of normal surface singularities, Topology 20 (1981), 219–246. 10.1016/0040-9383(81)90001-XSearch in Google Scholar
© 2019 Walter de Gruyter GmbH, Berlin/Boston
Articles in the same Issue
- Frontmatter
- Homotopy techniques for tensor decomposition and perfect identifiability
- Schottky groups acting on homogeneous rational manifolds
- Limit linear series for curves not of compact type
- Uniform congruence counting for Schottky semigroups in SL2(𝐙)
- The dualizing sheaf on first-order deformations of toric surface singularities
- Embedded minimal surfaces of finite topology
- Spectral gap characterization of full type III factors
- On the universal cover and the fundamental group of an RCD*(K,N)-space
- Calabi–Yau and fractional Calabi–Yau categories
Articles in the same Issue
- Frontmatter
- Homotopy techniques for tensor decomposition and perfect identifiability
- Schottky groups acting on homogeneous rational manifolds
- Limit linear series for curves not of compact type
- Uniform congruence counting for Schottky semigroups in SL2(𝐙)
- The dualizing sheaf on first-order deformations of toric surface singularities
- Embedded minimal surfaces of finite topology
- Spectral gap characterization of full type III factors
- On the universal cover and the fundamental group of an RCD*(K,N)-space
- Calabi–Yau and fractional Calabi–Yau categories