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A Degree Formula for Secant Varieties of Curves

  • Rüdiger Achilles (a1), Mirella Manaresi (a1) and Peter Schenzel (a2)
Abstract

Using the Stückrad–Vogel self-intersection cycle of an irreducible and reduced curve in pro-jective space, we obtain a formula that relates the degree of the secant variety, the degree and the genus of the curve and the self-intersection numbers, the multiplicities and the number of branches of the curve at its singular points. From this formula we deduce an expression for the difference between the genera of the curve. This result shows that the self-intersection multiplicity of a curve in projective N-space at a singular point is a natural generalization of the intersection multiplicity of a plane curve with its generic polar curve. In this approach, the degree of the secant variety (up to a factor 2), the self-intersection numbers and the multiplicities of the singular points are leading coefficients of a bivariate Hilbert polynomial, which can be computed by computer algebra systems.

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1.Achilles, R. and Aliffi, D., Segre, a script for the Reduce package Cali, University of Bologna (2012) (available at www.dm.unibo.it/~achilles/segre/).
2.Achilles, R. and Manaresi, M., An algebraic characterization of distinguished varieties of intersection, Rev. Roumaine Math. Pures Appl. 38 (1993), 569578.
3.Achilles, R. and Manaresi, M., Multiplicities of a bigraded ring and intersection theory, Math. Ann. 309 (1997), 573591.
4.Achilles, R. and Vogel, W., On multiplicities for improper intersections, J. Alg. 168 (1994), 123142.
5.Briançon, J., Galligo, A. and Granger, M., Déformations équisingidières des germes de courbes gauches réduites, Volume 1, p. 69 (Société Mathématiques de France, Paris, 1981).
6.Buchweitz, R.-O. and Greuel, G.-M., The Milnor number and deformations of complex curve singularities, Invent. Math. 58 (1980), 241281.
7.Chądzyński, J., Krasiński, T. and Tworzewski, P., On the intersection multiplicity of analytic curves in ℂm, Bull. Polish Acad. Sci. Math. 45 (1997), 163169.
8.Dale, M., Terracini's lemma and the secant variety of a curve, Proc. Lond. Math. Soc. 49 (1984), 329339.
9.Fischer, G., Plane algebraic curves (American Mathematical Society, Providence, RI, 2001).
10.Flenner, H. and Manaresi, M., Intersection of projective varieties and generic projections, Manuscr. Math. 92 (1997), 273286.
11.Flenner, H., O'Carroll, L. and Vogel, W., Joins and intersections, Springer Monographs in Mathematics (Springer, 1999).
12.Griffiths, Ph. and Harris, J., Principles of algebraic geometry, Pure and Applied Mathematics, Volume 52 (Wiley, 1978).
13.Harris, J., Algebraic geometry: a first course, Graduate Texts in Mathematics, Volume 133 (Springer, 1995).
14.Hartshorne, R., Algebraic geometry, Graduate Texts in Mathematics, Volume 52 (Springer, 1977).
15.Krasiński, T., Improper intersection of analytic curves, Univ. Iagel. Acta Math. 39 (2001), 153166.
16., D. T., Computation of the Milnor number of an isolated singularity of a complete intersection, Funkcional. Analysis i Priložen 8 (1974), 4549 (in Russian).
17.Mond, B. and Pellikaan, R., Fitting ideals and multiple points of analytic mappings, in Algebraic geometry and complex analysis (ed. de Arellano, R.), Lecture Notes in Mathematics, Volume 1414, pp. 107161 (Springer, 1989).
18.Peters, C. A. M. and Simonis, J., A secant formula, Q. J. Math. 27 (1976), 181189.
19.Ranestad, K., The degree of the secant variety and the join of monomial curves, Collectanea Math. 57 (2006), 2741.
20.Rosenlicht, M., Equivalence relations on algebraic curves, Annals Math. 56 (1952), 169191.
21.Semple, J. G. and Roth, L., Introduction to algebraic geometry, Oxford Science Publications (Clarendon, Oxford, 1985).
22.Serre, J.-P., Algebraic groups and class fields (Springer, 1988).
23.Stückrad, J. and Vogel, W., An algebraic approach to the intersection theory, in The curves seminar at Queen's, Volume II, pp. 132, Queen's Papers in Pure and Applied Mathematics, Volume 61 (Queen's University, Kingston, ON, 1982).
24.Stückrad, J. and Vogel, W., An Euler-Poincare characteristic for improper intersections, Math. Ann. 274 (1986), 257271.
25.Van Gastel, L. J., Excess intersections, PhD Thesis, Rijksuniversiteit Utrecht (1989).
26.Van Gastel, L. J., Excess intersections and a correspondence principle, Invent. Math. 103 (1991), 197221.
27.Whitney, H., Local properties of analytic varieties, in Differential and Combinatorial Topology (A Symposium in Honor of Marston Morse), pp. 205244 (Princeton University Press, Princeton, NJ, 1965).
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Proceedings of the Edinburgh Mathematical Society
  • ISSN: 0013-0915
  • EISSN: 1464-3839
  • URL: /core/journals/proceedings-of-the-edinburgh-mathematical-society
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