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Strong linear preservers of symmetric doubly stochastic or doubly substochastic matrices

โœ Scribed by Shwu-Huey Lin; Bit-Shun Tam


Publisher
Elsevier Science
Year
2004
Tongue
English
Weight
279 KB
Volume
379
Category
Article
ISSN
0024-3795

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โœฆ Synopsis


Let S denote either the set of n ร— n symmetric doubly stochastic matrices or the set of n ร— n symmetric doubly substochastic matrices and let T be a linear map on span S. We prove that T (S) = S if and only if there exists an n ร— n permutation matrix P such that T (X) = P t XP for all X โˆˆ span S. Our proofs make use of the concept of neighborly extreme points of a polytope and depend on some intricate graph theory.


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A note on the boundary of the set where
โœ Bassam Mourad ๐Ÿ“‚ Article ๐Ÿ“… 2006 ๐Ÿ› Elsevier Science ๐ŸŒ English โš– 172 KB

In this paper, we study the region s n of R n where the decreasingly ordered spectra of all the nร—n symmetric doubly stochastic matrices lie with emphasis on the boundary set of s n . As applications, we study the case n = 4 and in particular we solve the inverse eigenvalue problem for 4ร—4 symmetric