Fabrizio Zanello, Partial Derivatives of a Generic Subspace of a Vector Space of Forms: Quotients of Level Algebras of Arbitrary Type, Transactions of the American Mathematical Society, Vol. 359, No.

Resolving the invariant subspace problem for operators on Hilbert spaces has been stubbornly difficult, and it is this which Enflo claims to have achieved.

Two weeks ago, a modest-looking paper was uploaded to the arXiv preprint server with the unassuming title On the invariant subspace problem in Hilbert spaces. The paper is just 13 pages long and ...

Aside from his work on the invariant subspace problem, Enflo solved two other major problems – the basis problem and the approximation problem – both of which had remained open for more than ...