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It is the purpose of the present contribution to demonstrate that the generalization of the concept of a quantum mechanical observable from the Hermitian operator of standard quantum mechanics to a positive operator-valued measure is not a…

Quantum Physics · Physics 2017-08-23 Willem M. de Muynck

Recently the behavior of operator monotone functions on unbounded intervals with respect to the relation of strictly positivity has been investigated. In this paper we deeply study such behavior not only for operator monotone functions but…

Functional Analysis · Mathematics 2017-09-26 M. Fujii , M. S. Moslehian , H. Najafi , R. Nakamoto

In this paper we consider a one quartic operator on the $\mathbb{R}^2$ with positive coefficients. Positive fixed points for a quartic operator, were investigated. Theorems on number of positive fixed points of the quartic operator, are…

Functional Analysis · Mathematics 2020-07-14 Yu. Kh. Eshkabilov , Sh. D. Nodirov

The main goal of this paper is to discuss the recent advancements of operator means for accretive matrices in a more general setting. In particular, we present the general form governing the well established definition of geometric mean,…

Functional Analysis · Mathematics 2021-04-16 Yassine Bedrani , Fuad Kittaneh , Mohammed Sababheh

Given a topological group $G$ and a unitary representation $U$ of $G$, we consider the problem of classifying the positive operator measures which are based on a $G$-homogeneous space $X$ and covariant with respect to the representation…

Mathematical Physics · Physics 2007-05-23 Alessandro Toigo

The most general type of measurement in quantum physics is modeled by a positive operator-valued measure (POVM). Mathematically, a POVM is a generalization of a measure, whose values are not real numbers, but positive operators on a Hilbert…

Logic in Computer Science · Computer Science 2014-12-31 Frank Roumen

In various research areas related to decision making, problems and their solutions frequently rely on certain functions being monotonic. In the case of non-monotonic functions, one would then wish to quantify their lack of monotonicity. In…

Probability · Mathematics 2017-11-01 Youri Davydov , Ričardas Zitikis

Kiukas, Lahti and Ylinen asked the following general question. When is a positive operator measure projection valued? A version of this question formulated in terms of operator moments was posed in a recent paper of the present authors. Let…

Functional Analysis · Mathematics 2025-08-13 Paweł Pietrzycki , Jan Stochel

Motivated by a geometric meaning of Mahler's measure, we introduce two operator analogues of Mahler's measure. This leads to some interesting equalities and inequalities between the two operator-theoretic Mahler measures and the classical…

Functional Analysis · Mathematics 2013-12-19 Kunyu Guo , Jiayang Yu

Let $A_{i}\ (i=1, 2, ..., k)$ be bounded linear operators on a Hilbert space. This paper aims to show characterizations of operator order $A_{k}\geq A_{k-1}\geq...\geq A_{2}\geq A_{1}>0$ in terms of operator inequalities. Afterwards, an…

Functional Analysis · Mathematics 2011-11-17 Jian Shi , Zongsheng Gao

The purpose of this paper is to introduce the logarithmic mean of two convex functionals that extends the logarithmic mean of two positive operators. Some inequalities involving this functional mean are discussed as well. The operator…

Functional Analysis · Mathematics 2020-10-07 Mustapha Raïssouli , Shigeru Furuichi

Generalization of functions of bounded mean oscillation and Hankel operators to the case of compact abelian groups with linearly ordered dual is considered. Spaces of functions of bounded mean oscillation and of bounded mean oscillation of…

Functional Analysis · Mathematics 2019-02-26 A. R. Mirotin , R. V. Dyba

We introduce and study a class of betweenness algebras-Boolean algebras with binary operators, closely related to ternary frames with a betweenness relation. From various axioms for betweenness, we chose those that are most common, which…

Logic · Mathematics 2023-09-04 Ivo Duentsch , Rafal Gruszczynski , Paula Menchon

In this paper, we show refined Young inequalities for two positive operators. Our results refine the ordering relations among the arithmetic mean, the geometric mean and the harmonic mean for two positive operators. In addition, we give two…

Functional Analysis · Mathematics 2011-04-26 Shigeru Furuichi

One of the basic sanity properties of a behavioural semantics is that it constitutes a congruence with respect to standard process operators. This issue has been traditionally addressed by the development of rule formats for transition…

Logic in Computer Science · Computer Science 2010-08-13 Maciej Gazda , Wan Fokkink

For positive definite matrices $A$ and $B$, the Kubo-Ando matrix power mean is defined as $$ P_\mu(p, A, B) = A^{1/2}\left(\frac{1+(A^{-1/2}BA^{-1/2})^p}{2}\right )^{1/p} A^{1/2}\quad (p \ge 0). $$ In this paper, for $0\le p \le 1 \le q$,…

Functional Analysis · Mathematics 2021-07-14 Trung Hoa Dinh , Cong Trinh Le , The Van Nguyen , Bich Khue Vo

Recently, the authors studied the connection between each maximal monotone operator T and a family H(T) of convex functions. Each member of this family characterizes the operator and satisfies two particular inequalities. The aim of this…

Functional Analysis · Mathematics 2008-02-13 Regina Sandra Burachik , B. F. Svaiter

Many studies have been conducted on statistical convergence, and it remains an area of active research. Since its introduction, statistical convergence has found applications many fields. Nevertheless, there is a shortage of research…

Functional Analysis · Mathematics 2024-06-14 Erdal Bayram , Mehmet Küçükaslan , Mikail Et , Abdullah Aydın

We show that a positive operator between $L^p$-spaces is given by integration against a kernel function if and only if the image of each positive function has a lower semi-continuous representative with respect to a suitable topology. This…

Functional Analysis · Mathematics 2024-06-11 Moritz Gerlach , Jochen Glück

We prove that the functions t -> (t^q-1)(t^p-1)^{-1} are operator monotone in the positive half-axis for 0 < p < q < 1, and we calculate the two associated canonical representation formulae. The result is used to find new monotone metrics…

Operator Algebras · Mathematics 2009-02-08 Frank Hansen