English

Determinantal representation and subschemes of general plane curves

Algebraic Geometry 2010-12-16 v1 Commutative Algebra

Abstract

Let M=(mij)M = (m_{ij}) be an n×nn \times n square matrix of integers. For our purposes, we can assume without loss of generality that MM is homogeneous and that the entries are non-increasing going leftward and downward. Let dd be the sum of the entries on either diagonal. We give a complete characterization of which such matrices have the property that a general form of degree dd in C[x0,x1,x2]\mathbb C[x_0,x_1,x_2] can be written as the determinant of a matrix of forms (fij)(f_{ij}) with degfij=mij\deg f_{ij} = m_{ij} (of course fij=0f_{ij} = 0 if mij<0m_{ij} < 0). As a consequence, we answer the related question of which (n1)×n(n-1) \times n matrices QQ of integers have the property that a general plane curve of degree dd contains a zero-dimensional subscheme whose degree Hilbert-Burch matrix is QQ. This leads to an algorithmic method to determine properties of linear series contained in general plane curves.

Keywords

Cite

@article{arxiv.1012.3396,
  title  = {Determinantal representation and subschemes of general plane curves},
  author = {Luca Chiantini and Juan Migliore},
  journal= {arXiv preprint arXiv:1012.3396},
  year   = {2010}
}

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14 pages