Subspaces of matrices with special rank properties
Résumé
Let K be a field and let V be a vector space of finite dimension n over K. We investigate properties of a subspace M of EndK (V ) of dimension n(n − r + 1) in which each non-zero element of M has rank at least r and show that such subspaces exist if K has a cyclic Galois extension of degree n. We also investigate the maximum dimension of a constant rank r subspace of EndK (V ) when K is finite.