Characterizations of zero-dimensional complete intersections

Martin Kreuzer1, Le Ngoc Long1,2
1Fakultät für Informatik und Mathematik, Universität Passau, Passau, Germany
2Department of Mathematics, Hue University’s College of Education, Hue, Vietnam

Tóm tắt

Given a 0-dimensional subscheme  $${\mathbb X}$$ of a projective space  $${\mathbb P}^n_K$$ over a field K, we characterize in different ways whether  $${\mathbb X}$$ is the complete intersection of n hypersurfaces. Besides a generalization of the notion of a Cayley–Bacharach scheme, these characterizations involve the Kähler and the Dedekind different of the homogeneous coordinate ring of  $${\mathbb X}$$ or its Artinian reduction. We also characterize arithmetically Gorenstein schemes in novel ways and bring in further tools such as the module of regular differential forms, the fundamental class, and the Jacobian module of  $${\mathbb X}$$ . Throughout we strive to work over an arbitrary base field K and keep the scheme  $${\mathbb X}$$ as general as possible, thereby improving several known characterizations.

Tài liệu tham khảo

The ApCoCoA Team. ApCoCoA: approximate computations in commutative algebra (2007). http://www.apcocoa.org

Bruns, W., Herzog, J.: Cohen–Macaulay Rings Cambridge Stud. Adv. Math., vol. 39. Cambridge University Press, Cambridge (1993)

Bourbaki, N.: Commutative Algebra, Chap. 1–7. Springer, Berlin (1989)

Davis, E., Maroscia, P.: Complete intersections in \({\mathbb{P}^2}\): Cayley–Bacharach characterizations. In: Complete Intersections- Acireale 1983. In: Lecture Notes in Mathematics, vol. 1092, pp. 253–269 (1984)

Geramita, A.V., Maroscia, P.: The ideal of forms vanishing at a finite set of points in \(\mathbb{P}^n\). J. Algebra 90, 528–555 (1984)

Geramita, A.V., Orecchia, F.: On the Cohen–Macaulay type of \(s\)-lines in \(\mathbb{A}^{n+1}\). J. Algebra 70, 116–140 (1981)

Goto, S., Watanabe, K.: On graded rings I. J. Math. Soc. Jpn. 30, 179–213 (1978)

M. Kreuzer: Beiträge zur Theorie der nulldimensionalen Unterschemata projektiver Räume, Regensburger Math. Schr. 26, Universität Regensburg (1998)

Kreuzer, M.: On the canonical ideal of a set of points, Boll. U.M.I. (8) 1-B, 221–261 (2000)

Kreuzer, M., Robbiano, L.: Commutational Commutative Algebra 1. Springer, Heidelberg (2000)

Kreuzer, M., Robbiano, L.: Commutational Commutative Algebra 2. Springer, Heidelberg (2005)

Kunz, E.: Kähler differentials. In: Adv. Lectures Math. Wieweg Verlag, Braunschweig (1986)

Kunz, E., Waldi, R.: Regular differential forms. Contemporary Mathematics, vol. 79. Am. Math. Soc., Providence (1988)

Long, Le Ngoc: Various Differents for 0-Dimensional Schemes and Appplications. Universtät Passau, Passau (2015)

Morandi, P.: Field and Galois Theory. Springer, New York (1996)

Zariski, O., Samuel, P.: Commutative Algebra, vol. 1. van Nostrand, Princeton (1958)