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Related papers: Birkhoff-James Orthogonality and Its Pointwise Sym…

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We study Birkhoff-James orthogonality and its local symmetry in some sequence spaces namely $\ell_p,$ for $1\leq p\leq\infty$, $p\neq2$, $c$, $c_0$ and $c_{00}$. Using the characterization of the local symmetry of Birkhoff-James…

Functional Analysis · Mathematics 2022-05-25 Babhrubahan Bose , Saikat Roy , Debmalya Sain

In this paper, we extend the investigations regarding Birkhoff-James orthogonality of linear operators to bounded continuous functions on metric spaces. We introduce Birkhoff-James extensions of continuous functions and study them in…

Functional Analysis · Mathematics 2021-08-31 Saptak Bhattacharya

We classify bijective maps which strongly preserve Birkhoff-James orthogonality on a finite-dimensional complex $C^*$-algebra. It is shown that those maps are close to being real-linear isometries whose structure is also determined.

Operator Algebras · Mathematics 2025-02-13 Bojan Kuzma , Srdjan Stefanović

We classify real or complex finite-dimensional $C^*$-algebras and their underlying fields from the properties of Birkhoff-James orthogonality. Application to strong Birkhoff-James orthogonality preservers is also given.

Operator Algebras · Mathematics 2024-11-26 Bojan Kuzma , Sushil Singla

It is shown that every linear strong Birkhoff-James isomorphism between unital $C^*$-algebras is a $*$-isomorphism followed by a unitary multiplication. Moreover, as a partial extension of this result to the non-unital case, the form of…

Operator Algebras · Mathematics 2025-10-29 Bojan Kuzma , Srdjan Stefanović , Ryotaro Tanaka

We study the relationship between the point-wise symmetry of Birkhoff-James orthogonality and the geometry of the space of operators $\mathbb{B}(\ell_\infty^n,\ell_1^m)$. We show that any non-zero left-symmetric point in this space is a…

Functional Analysis · Mathematics 2022-11-17 Babhrubahan Bose

In this paper, we study Birkhoff-James orthogonality of bounded linear operators and give a complete characterization of Birkhoff-James orthogonality of bounded linear operators on infinite dimensional real normed linear spaces. As an…

Functional Analysis · Mathematics 2024-08-13 Debmalya Sain , Kallol Paul , Arpita Mal

There are two notions of approximate Birkhoff-James orthogonality in a normed space. We characterize both the notions of approximate Birkhoff-James orthogonality in the space of bounded linear operators defined on a normed space. A complete…

Functional Analysis · Mathematics 2024-08-13 Kallol Paul , Debmalya Sain , Arpita Mal

This paper deals with study of Birkhoff-James orthogonality of a linear operator to a subspace of operators defined between arbitrary Banach spaces. In case the domain space is reflexive and the subspace is finite dimensional we obtain a…

Functional Analysis · Mathematics 2019-12-10 Arpita Mal , Kallol Paul

In the last few decades, the concept of Birkhoff-James orthogonality has been used in several applications. In this survey article, the results known on the necessary and sufficient conditions for Birkhoff-James orthogonality in certain…

Functional Analysis · Mathematics 2024-03-13 Priyanka Grover , Sushil Singla

In this paper, we obtain some characterizations of the (strong) Birkhoff--James orthogonality for elements of Hilbert $C^*$-modules and certain elements of $\mathbb{B}(\mathscr{H})$. Moreover, we obtain a kind of Pythagorean relation for…

Operator Algebras · Mathematics 2021-07-23 Mohammad Sal Moslehian , Ali Zamani

We determine the exact diameter of the orthograph related to mutual strong Birkhoff-James orthogonality in arbitrary finite dimensional $C^{*}$-algebra. Additionally, we will estimate the distance between vertices in an arbitrary…

Operator Algebras · Mathematics 2024-02-16 Srdjan Stefanović

We study the concepts of Birkhoff--James orthogonality and parallelism in Hilbert space operators, induced by the operator radius norm $w_{\rho}(\cdot)$. In particular, we completely characterize Birkhoff--James orthogonality and…

Functional Analysis · Mathematics 2024-05-14 Fuad Kittaneh , Ali Zamani

Two different notions of approximate Birkhoff-James orthogonality in nor\-med linear spaces have been introduced by Dragomir and Chmie\-li\'n\-ski. In the present paper we consider a global and a local approximate symmetry of the…

Functional Analysis · Mathematics 2020-12-16 Jacek Chmieliński , Divya Khurana , Debmalya Sain

In this paper we characterize Birkhoff-James orthogonality of linear operators defined on a finite dimensional real Banach space $ \mathbb{X}. $ We also explore the symmetry of Birkhoff-James orthogonality of linear operators defined on $…

Functional Analysis · Mathematics 2016-07-29 Debmalya Sain

We characterize Birkhoff-James orthogonality of continuous vector-valued functions on a compact topological space. As an application of our investigation, Birkhoff-James orthogonality of real bilinear forms are studied. This allows us to…

Functional Analysis · Mathematics 2024-07-19 Saikat Roy , Tanusri Senapati , Debmalya Sain

We study the norm derivatives in the context of Birkhoff-James orthogonality in real Banach spaces. As an application of this, we obtain a complete characterization of the left-symmetric points and the right-symmetric points in a real…

Functional Analysis · Mathematics 2020-09-25 Divya Khurana , Debmalya Sain

We study Birkhoff-James orthogonality of compact (bounded) linear operators between Hilbert spaces and Banach spaces. Applying the notion of semi-inner-products in normed linear spaces and some related geometric ideas, we generalize and…

Functional Analysis · Mathematics 2018-10-12 Debmalya Sain , Kallol Paul , Arpita Mal

Let $X$ be a complex Banach space and $x,y\in X$. By definition, we say that $x$ is Birkhoff-James orthogonal to $y$ if $ \|x+\lambda y\|_{X} \geq \|x\|_{X}$ for all $\lambda \in \mathbb{C}$. We prove that $x$ is Birkhoff-James orthogonal…

Functional Analysis · Mathematics 2020-10-05 Kousik Dhara , Narayan Rakshit , Jaydeb Sarkar , Aryaman Sensarma

We introduced and study a family of generalized norm on $C^*$-algebras and the notion of Birkhoff-James orthogonality and norm-parallelism with respect to these family of generalized norms are investigated.

Operator Algebras · Mathematics 2025-08-01 Hooriye Sadat Jalali Ghamsari , Mahdi Dehghani
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