Abstract
Motivation of this paper is an open problem exposed by B. Beauzamy [l]. Let M be a 3 X 3 matrix and d(M) is the distance to the diagonal algebra. Let α(M) = sup{∥P1 MP∥:P is a projection in the diagonal algebra} and then call K(M) = d(M)/α(M) the distance-coefficient of M. The following results are obtained: (1) If M’ has two zero-entries apart from its diagonal. then K(M) ≤3/2√2: (2) If M has one zero-entry apart from its diagonal, then K(M) ≤ √41/32; (3) If M is arbitrary, then K(M) √3/2.
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Beauzamy. B.. Introduction to Operator Theory and Invariant Subspace. North-Hollard. Amsterdam, New York.Oxford. Tokyo. 1988.
Chen. X. Y. Two basic problems of finite rank operators. Ph. D. Dissertation, Zhejiang Univ., 1996.
Horn.P. A. and Johnson. C. R. ⋅ Matrix Analysis. Cambridge University Press. 1991.
Parrott, S. K.. On a quotient norm and the Sz-Hagy Foias lifting theorem. J.Funct. Anal.. 30 (1978).311–328.
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This subject is supported by the National Natural Science Foundation of China and Natural Science Foundation of Zhejiang Province.
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Fangyan, L. Estimate for distance-coefficient of matrices. Appl. Math. Chin. Univ. 12, 441–446 (1997). https://doi.org/10.1007/s11766-997-0046-3
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DOI: https://doi.org/10.1007/s11766-997-0046-3