Dimension bounds for constant rank subspaces of symmetric bilinear forms over a finite field

Abstract

Let V be a vector space of dimension n over the finite field F_q, where q is odd, and let Symm(V) denote the space of symmetric bilinear forms defined on V x V. We investigate constant rank r subspaces of Symm(V) in this paper. We have proved elsewhere that such a subspace has dimension at most n when q is larger than r but in this paper we provide generally improved upper bounds. Our investigations yield information about common isotropic points for such constant rank subspaces, and also how the radicals of the elements in the subspace are distributed throughout V.