24 citations · 39 across the 8 of their papers we have counts for
10 papers
An improvement of the Blanco-Koldobsky-Turnšek characterization of isometries
Jayanta Manna, Kalidas Mandal, Kallol Paul +1
We present an improvement of the Blanco-Koldobsky-Turnšek characterization of isometries in normed linear spaces by using the concept of level vectors of an operator. In this conte…
A study on preservation of parallel pairs and triangle equality attainment pairs
Jayanta Manna, Kalidas Mandal, Kallol Paul +1
This paper investigates the structure and preservation of parallel pairs and triangle equality attainment (TEA) pairs in normed linear spaces. We begin by providing functional char…
Refinements of the Blanco-Koldobsky-Turnšek Theorem
Jayanta Manna, Kalidas Mandal, Kallol Paul +1
We refine the well-known Blanco-Koldobsky-Turnšek Theorem which states that a norm one linear operator defined on a Banach space is an isometry if and only if it preserves orthogon…
On approximate preservation of orthogonality and its application to isometries
Kalidas Mandal, Jayanta Manna, Kallol Paul +1
Motivated by the famous Blanco-Koldobsky-Turnšek characterization of isometries, we study the \textit{approximate preservation of Birkhoff-James orthogonality by a linear operator…
On directional preservation of orthogonality and its application to isometries
Jayanta Manna, Kalidas Mandal, Kallol Paul +1
We study the local preservation of Birkhoff-James orthogonality by linear operators between normed linear spaces, at a point and in a particular direction. We obtain a complete cha…
On uniform Bishop-Phelps-Bollobás type approximations of linear operators and preservation of geometric properties
Debmalya Sain, Arpita Mal, Kalidas Mandal +1
We study uniform BPB approximations of bounded linear operators between Banach spaces from a geometric perspective. We show that for sufficiently small positive values of …
On the numerical range of operators on some special Banach spaces
Kalidas Mandal, Aniket Bhanja, Santanu Bag +1
The numerical range of a bounded linear operator on a complex Banach space need not be convex unlike that on a Hilbert space. The aim of this paper is to study operators on $ \…
A complete characterization of Radon planes whose unit spheres are regular polygons
Kalidas Mandal, Debmalya Sain, Kallol Paul
We study the structure of the unit sphere of polygonal Radon planes from a geometric point of view. In particular, we prove that a -dimensional real polygonal Banach space $ \…
On two extremum problems related to the norm of a bounded linear operator
Debmalya Sain, Kallol Paul, Kalidas Mandal
We explore the norm attainment set and the minimum norm attainment set of a bounded linear operator between Hilbert spaces and Banach spaces. Indeed, we obtain a complete character…
Orthogonality of bounded linear operators on complex Banach spaces
Kallol Paul, Debmalya Sain, Arpita Mal +1
We study Birkhoff-James orthogonality of bounded linear operators on complex Banach spaces and obtain a complete characterization of the same. By means of introducing new definitio…