Kazan (Volga region) Federal University, KFU
KAZAN
FEDERAL UNIVERSITY
 
CHARACTERIZATIONS OF TRACIAL FUNCTIONALS ON $C^*$-ALGEBRAS
Form of presentationArticles in international journals and collections
Year of publication2025
Языканглийский
  • Bikchentaev Ayrat Midkhatovich, author
  • Moslehian Mohammad Sal, author
  • Bibliographic description in the original language Airat M. Bikchentaev and Mohammad Sal Moslehian, Characterizations of tracial functionals on $C^*$-algebras, Infinite Dimensional Analysis, Quantum Probability and Related Topics (2025) Vol. 28, no 1. 2550003 (14 pages) World Scientific Publishing Company DOI: 10.1142/S0219025725500031
    Annotation We establish several characterizations of tracial functionals φ on the finite C∗-algebra 𝕄n (that is, φ=k tr for some number k>0) via any one of the inequalities φ(AαB1−α)≤αφ(A)+(1−α)φ(B) and φ(|eA|)≤φ(eReA), which are well-known when φ=tr. In addition, we characterize the trace on 𝕄n among all positive linear functionals φ with φ(I)=n through an inequality for determinant. We lso establish that such a functional is equal to the usual trace if and only if φ((B12AB12)m)≤φ(A)mφ(B)m for all positive integers m and all A,B∈𝕄n+. Furthermore, we show that there is no state φ on 𝕄n,n≥2 such that φ(B1/2AB1/2)≤φ(A)φ(B) for all A,B∈𝕄n+. Finally, we establish that for a positive linear functional φ on a C ∗ -algebra 𝒜 , the following conditions are equivalent: (i) φ is tracial; (ii) φ ( e A B − I ) ≥ 0 for all A , B ∈ 𝒜 + . A new criterion for the commutativity of C ∗ -algebras is also provided.
    Keywords Hilbert space, von Neumann algebra, trace, tracial inequality, matrix, positive linear functional
    The name of the journal Infinite Dimensional Analysis, Quantum Probability and Related Topics
    Please use this ID to quote from or refer to the card https://repository.kpfu.ru/eng/?p_id=312585&p_lang=2
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