Regularity bounds for curves by minimal generators and Hilbert function

Francesca Cioffi, Maria Grazia Marinari, Luciana Ramella

Published 2005-07-28, updated 2006-02-02Version 2

Let $\rho_C$ be the regularity of the Hilbert function of a projective curve $C$ in $\mathbb P^n_K$ over an algebraically closed field $K$ and $\alpha_1,...,\alpha_{n-1}$ be minimal degrees for which there exists a complete intersection of type $(\alpha_1,...,\alpha_{n-1})$ containing the curve $C$. Then the Castelnuovo-Mumford regularity of $C$ is upper bounded by $\max\{\rho_C+1,\alpha_1+...+\alpha_{n-1}-(n-2)\}$. We study and, for space curves, refine the above bound providing several examples.