IJPAM: Volume 93, No. 6 (2014)

GENERAL UNIONS OF SUNDIALS (OR LINES)
IMPROVE THE HILBERT FUNCTIONS
OF PROJECTIVE SCHEMES

E. Ballico
Department of Mathematics
University of Trento
38 123 Povo (Trento) - Via Sommarive, 14, ITALY


Abstract. A sundial $T\subset \mathbb {P}^r$ is a certain flat limit of two disjoint lines with $T_{\red}$ a reducible conic. Let $A\subset \mathbb {P}^r$, $r$ large, the double of a linear space. We prove that a general union of $A$ and lines or sundials has the expected postulation. Instead of $A$ we may take other low dimensional multiple structures if certain numerical conditions on their Hilbert function are satisfied.

Received: February 22, 2014

AMS Subject Classification: 14N05

Key Words and Phrases: sundial, lines, postulation, Hilbert function

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DOI: 10.12732/ijpam.v93i6.4 How to cite this paper?

Source:
International Journal of Pure and Applied Mathematics
ISSN printed version: 1311-8080
ISSN on-line version: 1314-3395
Year: 2014
Volume: 93
Issue: 6
Pages: 789 - 798

CC BY This work is licensed under the Creative Commons Attribution International License (CC BY).