Large spaces of symmetric matrices of bounded rank are decomposable

Authors
Citation
R. Loewy, Large spaces of symmetric matrices of bounded rank are decomposable, LINEAR MULT, 48(4), 2001, pp. 355-382
Citations number
7
Categorie Soggetti
Mathematics
Journal title
LINEAR & MULTILINEAR ALGEBRA
ISSN journal
03081087 → ACNP
Volume
48
Issue
4
Year of publication
2001
Pages
355 - 382
Database
ISI
SICI code
0308-1087(2001)48:4<355:LSOSMO>2.0.ZU;2-9
Abstract
Let k and n be positive integers such that k less than or equal to n. Let S -n(F) denote the space of all n x n symmetric matrices over the field F wit h char F not equal 2. A subspace L of S-n(F) is said to be a k-subspace if rank A less than or equal to k for every A is an element of L. Now suppose that k is even, and write k=2r. We say a (k) over bar -subspace of S-n(F) is decomposable if there exists in F-n a subspace W of dimension n - r such that x(t)Ax = 0 for every x is an element of W, A is an element of L. We show here, under some mild assumptions on k, n and F, that every Tc-subs pace of S-n(F) of sufficiently large dimension must be decomposable. This i s an analogue of a result obtained by Atkinson and Lloyd for corresponding subspaces of F-m,F-n.