Abstract: In this paper, we introduce the notion of a homogeneous ideal in quasi stable position (QSP); a new definition for the notion of generic coordinates to compute efficiently the Castelnuovo-Mumford regularity of a homogeneous ideal. This definition is simple to check, because it is tested on the initial ideal for the degree reverse lexicographic ordering. It is explicit, because we provide an algorithm to decide whether a monomial ideal is in QSP or not. The main result of this paper is that the Castelnuovo-Mumford regularity of an ideal in QSP is the maximal degree of the elements of its reduced Gröbner basis with respect to the reverse lexicographic ordering. We have implemented an algorithm in (the distributed library noether.lib of) SINGULAR based on the above results for computing the Castelnuovo-Mumford regularity of a general ideal, and we evaluate its performance via some examples.
7.David
Eisenbud, Commutative algebra, Graduate Texts in Mathematics,
vol. 150, Springer-Verlag, New York, 1995. With a view toward
algebraic geometry. MR 1322960
(97a:13001)
10.André
Galligo, À propos du théorème
de-préparation de Weierstrass, Fonctions de plusieurs variables
complexes (Sém. François Norguet, octobre
1970–décembre 1973; à la mémoire
d’André Martineau), Springer, Berlin, 1974,
pp. 543–579. Lecture Notes in Math., Vol. 409 (French).
Thèse de 3ème cycle soutenue le 16 mai 1973 à
l’Institut de Mathématique et Sciences Physiques de
l’Université de Nice. MR 0402102
(53 #5924)
12.Mark
L. Green, Generic initial ideals, Six lectures on commutative
algebra (Bellaterra, 1996) Progr. Math., vol. 166, Birkhäuser,
Basel, 1998, pp. 119–186. MR 1648665
(99m:13040)
13.
G.-M. Greuel, G. Pfister, and H. Schönemann. SINGULAR 3.0. A Computer Algebra System for Polynomial Computations, Centre for Computer Algebra, University of Kaiserslautern, 2005.
14.D.
Lazard, Gröbner bases, Gaussian elimination and resolution of
systems of algebraic equations, Computer algebra (London, 1983)
Lecture Notes in Comput. Sci., vol. 162, Springer, Berlin, 1983,
pp. 146–156. MR 774807
(86m:13002)
Amir Hashemi Affiliation:
Department of Mathematical Sciences, Isfahan University of Technology, Isfahan 84156-83111, Iran
Email:
Amir.Hashemi@cc.iut.ac.ir