We study a separability problem suggested by mathematical description of bipartite quantum systems. We consider Hermitian 2-forms on the tensor product H = K ⊗ L, where K, L are finite dimensional complex spaces. Inspired by quantum mechanical terminology we call such a form separable if it is a convex combination of hermitian tensor products σ * p ⊙ σ p of 1-forms σ p on H that are product for...