Abstract
First we give a sharp upper bound for the cardinal m of a minimal set of generators for the module of Jacobian syzygies of a complex projective reduced plane curve C. Next we discuss the sharpness of an upper bound, given by A. du Plessis and C.T.C. Wall, for the global Tjurina number of such a curve C, in terms of its degree d and of the minimal degree \(r\le d-1\) of a Jacobian syzygy. We give a homological characterization of the curves whose global Tjurina number equals the du Plessis-Wall upper bound, which implies in particular that for such curves the upper bound for m is also attained. A second characterization of these curves in terms of the 0-th Fitting ideal of their Jacobian module is also given. Finally we prove the existence of curves with maximal global Tjurina numbers for certain pairs (d, r). We conjecture that such curves exist for any pair (d, r), and that, in addition, they may be chosen to be line arrangements when \(r\le d-2\). This conjecture is proved for degrees \(d \le 11\).
Similar content being viewed by others
References
Abe, T., Dimca, A., Sticlaru, G.: Addition-deletion results for the minimal degree of logarithmic derivations of hyperplane arrangements and maximal Tjurina line arrangements. J. Algeb. Combin. (2020). https://doi.org/10.1007/s10801-020-00986-9
Bartolo, E. Artal, Gorrochategui, L., Luengo, I., Melle-Hernández, A.: On some conjectures about free and nearly free divisors, In: Singularities and Computer Algebra, Festschrift for Gert-Martin Greuel on the Occasion of his 70th Birthday, pp. 1–19, Springer (2017)
Chardin, M.: Some results and questions on Castelnuovo–Mumford regularity. In: Syzygies and Hilbert functions, 1–40, Lecture Notes Pure Applied Mathematics, 254, Chapman & Hall/CRC, Boca Raton, FL (2007)
Choudary, A.D.R., Dimca, A.: Koszul complexes and hypersurface singularities. Proc. Am. Math. Soc. 121, 1009–1016 (1994)
Decker, W., Greuel, G.-M., Pfister, G., Schönemann, H.: Singular 4-0-1: A computer algebra system for polynomial computations. http://www.singular.uni-kl.de (2014)
Dimca, A.: Syzygies of Jacobian ideals and defects of linear systems, Bull. Math. Soc. Sci. Math. Roumanie Tome 56 (104) No. 2, 191–203 (2013)
Dimca, A.: Hyperplane Arrangements: An Introduction Universitext. Springer, New York (2017)
Dimca, A.: Freeness versus maximal global Tjurina number for plane curves. Math. Proc. Cambridge Phil. Soc. 163, 161–172 (2017)
Dimca, A.: Curve arrangements, pencils, and Jacobian syzygies. Michigan Math. J. 66, 347–365 (2017)
Dimca, A., Popescu, D.: Hilbert series and Lefschetz properties of dimension one almost complete intersections. Commun. Algebra 44, 4467–4482 (2016)
Dimca, A., Sticlaru, G.: Koszul complexes and pole order filtrations. Proc. Edinburg. Math. Soc. 58, 333–354 (2015)
Dimca, A., Sticlaru, G.: On the exponents of free and nearly free projective plane curves. Rev. Mat. Comput. 30, 259–268 (2017)
Dimca, A., Sticlaru, G.: Free divisors and rational cuspidal plane curves. Math. Res. Lett. 24, 1023–1042 (2017)
Dimca, A., Sticlaru, G.: Saturation of Jacobian ideals: some applications to nearly free curves, line arrangements and rational cuspidal plane curves. J. Pure Appl. Algebra 223, 5055–5066 (2019)
Dimca, A., Sticlaru, G.: Plane curves with three syzygies, minimal Tjurina curves, and nearly cuspidal curves. Geomet. Dedicata 207, 29–49 (2020)
Dimca, A., Sticlaru, G.: On the jumping lines of bundles of logarithmic vector fields along plane curves. Publ. Mat. 64, 513–542 (2020)
du Plessis, A.A., Wall, C.T.C.: Application of the theory of the discriminant to highly singular plane curves. Math. Proc. Cambridge Phil. Soc. 126, 259–266 (1999)
Eisenbud, D.: Commutative algebra with a view toward algebraic geometry, Graduate Texts in Mathematics, vol. 150. Springer, New York (1995)
Eisenbud, D.: The Geometry of Syzygies: A Second Course in Algebraic Geometry and Commutative Algebra, Graduate Texts in Mathematics, vol. 229. Springer, New York (2005)
Ellia, Ph.: Quasi complete intersections and global Tjurina number of plane curves. J. Pure Appl. Algebra 224, 423–431 (2020)
Ellia, Ph.: Quasi complete intersections in \({\mathbb{P}}^2\) and syzygies. Rend. Circ. Mat. Palermo II Ser 69, 813–822 (2020)
Harris, J.: On the Severi problem. Invent. Math. 84, 445–461 (1986)
Hassanzadeh, S.H., Simis, A.: Plane Cremona maps: saturation and regularity of the base ideal. J. Algebra 371, 620–652 (2012)
Ito, H., Noma, A., Ohno, M.: Maximal minors of a matrix with linear form entries. Linear Multilinear Algebra 63, 1599–1606 (2015)
Kouchnirenko, A.G.: Polyèdres de Newton et nombres de Milnor. Invent. Math. 32, 1–31 (1976)
Oka, M.: On Fermat curves and maximal nodal curves. Michigan Math. J. 53, 459–477 (2005)
Saito, K.: Theory of logarithmic differential forms and logarithmic vector fields. J. Fac. Sci. Univ. Tokyo Sect. IA Math 27(2), 265–291 (1980)
Schenck, H.: Elementary modifications and line configurations in \({\mathbb{P}}^2\). Commun. Math. Helv. 78, 447–462 (2003)
Sernesi, E.: The local cohomology of the Jacobian ring. Docum. Math. 19, 541–565 (2014)
Simis, A.: The depth of the Jacobian ring of a homogeneous polynomial in three variables. Proc. Am. Math. Soc. 134, 1591–1598 (2006)
Simis, A., Tohăneanu, S.O.: Homology of homogeneous divisors. Israel J. Math. 200, 449–487 (2014)
van Straten, D., Warmt, T.: Gorenstein duality for one-dimensional almost complete intersections-with an application to non-isolated real singularities. Math. Proc. Cambridge Phil. Soc. 158, 249–268 (2015)
Tohăneanu, S.O.: On freeness of divisors on \({\mathbb{P}}^2\). Commun. Algebra 41(8), 2916–2932 (2013)
Ziegler, G.: Combinatorial construction of logarithmic differential forms. Adv. Math. 76, 116–154 (1989)
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
A. Dimca: This work has been partially supported by the French government, through the \(\mathrm UCA^\mathrm{JEDI}\) Investments in the Future project managed by the National Research Agency (ANR) with the reference number ANR-15-IDEX-01 and by the Romanian Ministry of Research and Innovation, CNCS—UEFISCDI, Grant PN-III-P4-ID-PCE-2020-0029, within PNCDI III.
Rights and permissions
About this article
Cite this article
Dimca, A., Sticlaru, G. Jacobian syzygies, Fitting ideals, and plane curves with maximal global Tjurina numbers. Collect. Math. 73, 391–409 (2022). https://doi.org/10.1007/s13348-021-00325-6
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s13348-021-00325-6
Keywords
- Tjurina number
- Jacobian ideal
- Jacobian syzygy
- Free curve
- Nearly free curve
- Nearly cuspidal rational curve
- Maximal nodal curve