On the circular numerical range of 5-by-5 partial isometries

Autor:	Naimi, Mehdi, Benharrat, Mohammed
Rok vydání:	2021
Předmět:	Mathematics - Functional Analysis Mathematics - Operator Algebras Numerical range Partial isometric Kippenhahn curve
Druh dokumentu:	Working Paper
Popis:	We prove, in some cases in term of kippenhahn curve, that if 5-by-5 partial isometry whose numerical range is a circular disc then its center is must be the origin. This gives a partial affirmative answer of the Conjecture 5.1. of [H. l. Gau et al., Linear and Multilinear Algebra, 64 (1) 2016, 14--35.], for the five dimensional case.
Databáze:	arXiv
Externí odkaz:	http://arxiv.org/abs/2108.04459 Zobrazit plný text záznamu View this record from Arxiv