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Jun Tomiyama

Researcher at Niigata University

Publications -  5
Citations -  148

Jun Tomiyama is an academic researcher from Niigata University. The author has contributed to research in topics: Centrosymmetric matrix & Symmetric matrix. The author has an hindex of 4, co-authored 5 publications receiving 123 citations.

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On the geometry of positive maps in matrix algebras. II

TL;DR: In this article, the identity map, the transpose map, and the map τ(x)− 1 n (x) Tr (x)-1 n in the matrix algebra Mn are illustrated, providing parametric examples of maps which are not k+1-positive but which satisfy the matrix Schwartz inequality of order k for 1 ⩽ k⩽ n − 1.
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On the difference of n-positivity and complete positivity in C∗-algebras

TL;DR: For two C∗-algebras A and B, the authors showed that every n-positive map of A to B is n + 1-positive (afterwards completely positive) if and only if either A or B has only irreducible representations with dimensions less than n.
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Recent Development of the Theory of Completely Bounded Maps between C*-Algebras

TL;DR: The theory of completely bounded maps between C*-algebras has been studied in this article, where Wittstock, Smith, Paulsen, and Huruya have reviewed and discussed their results.