Numerical ranges of products of two positive contractions

dc.citation.epage	946	en_US
dc.citation.spage	939	en_US
dc.citation.volume	455	en_US
dc.contributor.author	Gau, Hwa-Long	en_US
dc.contributor.author	Wu, Pei Yuan	en_US
dc.contributor.department	應用數學系	zh_TW
dc.contributor.department	Department of Applied Mathematics	en_US
dc.date.accessioned	2018-08-21T05:54:22Z
dc.date.available	2018-08-21T05:54:22Z
dc.date.issued	2017-11-15	en_US
dc.description.abstract	Let A and B be positive contractions on a Hilbert space. It was known before that the numerical range W(AB) of their product is contained in the rectangular region [-1/8,1] x [-1/4,1/4]. In this paper, we determine exactly when W(AB) touches on its four sides. This follows from the more general information on a containing region of W(AB) and on when they share a common tangent line. We also give an example of A and B on three-dimensional space for which W (AB) is not symmetric with respect to the x-axis. (C) 2017 Elsevier Inc. All rights reserved.	en_US
dc.identifier.doi	10.1016/j.jmaa.2017.06.018	en_US
dc.identifier.issn	0022-247X	en_US
dc.identifier.journal	JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS	en_US
dc.identifier.uri	http://dx.doi.org/10.1016/j.jmaa.2017.06.018	en_US
dc.identifier.uri	https://ir.lib.nycu.edu.tw/handle/11536/145853
dc.identifier.wosnumber	WOS:000406568800004	en_US
dc.language.iso	en_US	en_US
dc.subject	Numerical range	en_US
dc.subject	Positive contraction	en_US
dc.title	Numerical ranges of products of two positive contractions	en_US
dc.type	Article	en_US

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