@article{f09b330c09e24e2dbf47d73fde8c1399,
title = "On subscalarity of some 2 × 2 class A operator matrices",
abstract = "In this paper we provide some conditions for 2×2 operator matrices whose diagonal entries are class A operators to be subscalar. As a corollary, we get that such operators with rich spectra have nontrivial invariant subspaces. In addition, we show that the tensor product of a 2×2 upper triangular class A operator matrix and a class A operator has a scalar extension. Finally, we find some subscalar 2×2 operator matrices satisfying the operator equations ABA=A2 and BAB=B2.",
keywords = "Class A operator, Invariant subspace, Subscalar",
author = "Eungil Ko and Sungeun Jung and Yoenha Kim",
note = "Funding Information: This work was supported by Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012-0006691). The second author was supported by the National Research Foundation of Korea Grant funded by the Korean Government (Ministry of Education, Science and Technology) [NRF-2011-355-1-C00005]. E-mail addresses: ssung105@ewhain.net (S. Jung), yoenha@ewhain.net (Y. Kim), eiko@ewha.ac.kr (E. Ko).",
year = "2013",
month = feb,
day = "1",
doi = "10.1016/j.laa.2012.08.037",
language = "English",
volume = "438",
pages = "1322--1338",
journal = "Linear Algebra and Its Applications",
issn = "0024-3795",
publisher = "Elsevier Inc.",
number = "3",
}