Helly-type theorem for eigenvectors

Abstract

We prove that if any $\lfloor 3d/2\rfloor$ or fewer elements of a finite family of linear operators ${\mathbb{K}}^d\to {\mathbb{K}}^d$ ($\mathbb{K}$ is an arbitrary field) have a common eigenvector then all operators in the family have a common eigenvector. Moreover, $\lfloor 3d/2\rfloor$ cannot be replaced by a smaller number. Also, we study the following problem, achieving partial results: prove that if any $l=O(d)$ or fewer elements of a finite family of linear operators ${\mathbb{K}}^d\to {\mathbb{K}}^d$ have a common non-trivial invariant subspace then all operators in the family have a common non-trivial invariant subspace.

v2: 6 pages, corrections are made in Section 2 v3: 6 pages, corrections are made in the proof of Lemma 1 (Section 3)

References in corpus (1)

• Inversion symmetry of Josephson current as test of chiral domain wall motion in Sr${}_2$RuO${}_4$