English

Exotic indecomposable systems of four subspaces in a Hilbert space

Functional Analysis 2007-05-23 v1 Operator Algebras

Abstract

We study the relative position of four subspaces in a Hilbert space. For any positive integer n, we give an example of exotic indecomposable system of four subspaces in a Hilbert space whose defect is (2n+1)/3. By an exotic system, we mean a system which is not isomorphic to any closed operator system under any permutation of subspaces. We construct the examples by a help of certain nice sequences used by Jiang and Wang in their study of strongly irreducible operators.

Keywords

Cite

@article{arxiv.math/0607085,
  title  = {Exotic indecomposable systems of four subspaces in a Hilbert space},
  author = {Masatoshi Enomoto and Yasuo Watatani},
  journal= {arXiv preprint arXiv:math/0607085},
  year   = {2007}
}

Comments

16pages

R2 v1 2026-07-22T17:38:27.188Z