The cubic Segre variety in PG(5, 2)

  • Authors:
  • Ron Shaw;Neil A. Gordon

  • Affiliations:
  • Centre for Mathematics, University of Hull, Hull, UK HU6 7RX;Department of Computer Science, University of Hull, Hull, UK HU6 7RX

  • Venue:
  • Designs, Codes and Cryptography
  • Year:
  • 2009

Quantified Score

Hi-index 0.00

Visualization

Abstract

The Segre variety $${\mathcal{S}_{1,2}}$$ in PG(5, 2) is a 21-set of points which is shown to have a cubic equation Q(x) = 0. If T(x, y, z) denotes the alternating trilinear form obtained by completely polarizing the cubic polynomial Q, then the associate U # of an r-flat $${U \subset {\rm PG}(5, 2)}$$ is defined to be $$U^{\#} = \{z \in {\rm PG}(5, 2)\,|\,T(u_{1}, u_{2}, z) = 0\, {\rm for \, all}\, u_{1}, u_{2} \in U\},$$ and so is an s-flat for some s. Those lines L of PG(5, 2) which are singular, satisfying that is L # = PG(5.2), are shown to form a complete spread of 21 lines. For each r-flat $${U \subset {\rm PG}(5, 2)}$$ its associate U # is determined. Examples are given of four kinds of planes P which are self-associate, P # = P, and three kinds of planes for which P, P #, P ## are disjoint planes such that P ### = P.