Abstract
We exploit an elementary specialization technique to study rational curves on Fano varieties of index one less than their dimension, known as del Pezzo manifolds. First, we study the splitting type of the normal bundles of the rational curves. Second, we prove a simple formula relating the number of rational curves passing through a suitable number of points in the case of threefolds and the analogous invariants for del Pezzo surfaces.
Acknowledgements
I would like to thank Erwan Brugallé, Yaim Cooper, Philip Engel, Penka Georgieva, János Kollár, Joe Harris, Quoc Ho, Anand Patel and Alex Perry for useful discussions. One chapter of the author’s doctoral thesis is based on this work.
Funding: While doing this work, I was indirectly supported by the National Science Foundation grant DMS-1308244, “Nonlinear Analysis on Sympletic, Complex Manifolds, General Relativity, and Graphs”.
References
[1] A. Beauville, Quantum cohomology of complete intersections. Mat. Fiz. Anal. Geom. 2 (1995), 384–398. MR1484335 Zbl 0863.14029Search in Google Scholar
[2] E. Brugallé, P. Georgieva, Pencils of quadrics and Gromov–Witten–Welschinger invariants of ℂP3. Math. Ann. 365 (2016), 363–380. MR3498914 Zbl 0658794410.1007/s00208-016-1398-xSearch in Google Scholar
[3] D. F. Coray, Enumerative geometry of rational space curves. Proc. London Math. Soc. (3) 46 (1983), 263–287. MR693041 Zbl 0479.1402310.1112/plms/s3-46.2.263Search in Google Scholar
[4] I. Coskun, J. Starr, Rational curves on smooth cubic hypersurfaces. Int. Math. Res. Not. (2009), no. 24, 4626–4641. MR2564370 Zbl 1200.1405110.1093/imrn/rnp102Search in Google Scholar
[5] D. Eisenbud, A. Van de Ven, On the normal bundles of smooth rational space curves. Math. Ann. 256 (1981), 453–463. MR628227 Zbl 0443.1401510.1007/BF01450541Search in Google Scholar
[6] T. Fujita, On the structure of polarized manifolds with total deficiency one. I. J. Math. Soc. Japan32 (1980), 709–725. MR589109 Zbl 0474.1401710.2969/jmsj/03240709Search in Google Scholar
[7] T. Fujita, Classification theories of polarized varieties. Cambridge Univ. Press 1990. MR1162108 Zbl 0743.1400410.1017/CBO9780511662638Search in Google Scholar
[8] L. Göttsche, R. Pandharipande, The quantum cohomology of blow-ups of ℙ2 and enumerative geometry. J. Differential Geom. 48 (1998), 61–90. MR1622601 Zbl 0946.1403310.4310/jdg/1214460607Search in Google Scholar
[9] K. Hulek, The normal bundle of a curve on a quadric. Math. Ann. 258 (1981/82), 201–206. MR641825 Zbl 0458.1401110.1007/BF01450535Search in Google Scholar
[10] V. A. Iskovskih, Fano threefolds. I/II. Izv. Akad. Nauk SSSR Ser. Mat. 41/42 (1977/1978), 516–562, 717/506–549. MR463151 MR503430 Zbl 0382.14013 Zbl 0424.14012Search in Google Scholar
[11] V. A. Iskovskih, Anticanonical models of three-dimensional algebraic varieties. J. Sov. Math. 13 (1980), 745–814. MR537685 Zbl 0428.1401610.1007/BF01084563Search in Google Scholar
[12] J. Kollár, Examples of vanishing Gromov–Witten–Welschinger invariants. J. Math. Sci. Univ. Tokyo22 (2015), 261–278. MR3329197 Zbl 1366.14049Search in Google Scholar
[13] Z. Ran, Normal bundles of rational curves in projective spaces. Asian J. Math. 11 (2007), 567–608. MR2402939 Zbl 1163.1402910.4310/AJM.2007.v11.n4.a3Search in Google Scholar
[14] M. Shen, On the normal bundles of rational curves on Fano 3-folds. Asian J. Math. 16 (2012), 237–270. MR2916363 Zbl 1253.1404810.4310/AJM.2012.v16.n2.a4Search in Google Scholar
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Articles in the same Issue
- Frontmatter
- The index of symmetry of three-dimensional Lie groups with a left-invariant metric
- Canonical contact unit cotangent bundle
- On the umbilicity of generalized linear Weingarten hypersurfaces in hyperbolic spaces
- Regular polyhedra in the 3-torus
- Rational curves on Del Pezzo manifolds
- Commuting matrices and the Hilbert scheme of points on affine spaces
- On rational varieties of small rationality degree
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Articles in the same Issue
- Frontmatter
- The index of symmetry of three-dimensional Lie groups with a left-invariant metric
- Canonical contact unit cotangent bundle
- On the umbilicity of generalized linear Weingarten hypersurfaces in hyperbolic spaces
- Regular polyhedra in the 3-torus
- Rational curves on Del Pezzo manifolds
- Commuting matrices and the Hilbert scheme of points on affine spaces
- On rational varieties of small rationality degree
- Skew symmetric logarithms and geodesics on On(ℝ)
- New homogeneous Einstein metrics on quaternionic Stiefel manifolds