English

On invariant graph subspaces

Spectral Theory 2016-08-03 v2 Functional Analysis

Abstract

In this paper we discuss the problem of decomposition for unbounded 2×22\times 2 operator matrices by a pair of complementary invariant graph subspaces. Under mild additional assumptions, we show that such a pair of subspaces decomposes the operator matrix if and only if its domain is invariant for the angular operators associated with the graphs. As a byproduct of our considerations, we suggest a new block diagonalization procedure that resolves related domain issues. In the case when only a single invariant graph subspace is available, we obtain block triangular representations for the operator matrices.

Keywords

Cite

@article{arxiv.1509.07984,
  title  = {On invariant graph subspaces},
  author = {Konstantin A. Makarov and Stephan Schmitz and Albrecht Seelmann},
  journal= {arXiv preprint arXiv:1509.07984},
  year   = {2016}
}

Comments

21 pages. This paper provides a complete overhaul and extension to the authors previous work arXiv:1307.6439 and includes an example

R2 v1 2026-06-22T11:06:08.209Z