6 citations · 17 across the 24 of their papers we have counts for
26 papers
On the Commutant of Invertible Positive Operators
Fuad Kittaneh, Carlos S. Kubrusly, Mohammad Sal Moslehian
An important result due to Radjabalipour asserts that if ${A\in\BB(\H)}$ is an invertible positive operator and ${T\in\BB(\H)}$ is arbitrary, then the operator sequence $\{A^{-n}TA…
Structural Properties and Normality Criteria for Subclasses of Normaloid Operators
Hranislav Stanković, Carlos Kubrusly
We investigate structural properties and normality criteria for certain classes of bounded linear operators on a Hilbert space. We show that an operator with polar decompositio…
Weak Quasistability and Rajchman measures
Carlos Kubrusly
It is shown that weak quasistability does not imply power boundedness, but coercive power unbounded operators cannot be weakly quasistable.\ Although a finite measure over the unit…
An Exposition on Weak Stability of Operators
C. S. Kubrusly
This is an expository survey on weak stability of bounded linear operators acting on normed spaces in general and, in particular, on Hilbert spaces. The paper gives a comprehensive…
Weak Supercyclicity -- An Expository Survey
Carlos S. Kubrusly
This is an exposition on supercyclicity and weak supercyclicity, especially designed to advance further developments in weakly supercyclicity, which is a recent research field show…
Convergence of power sequences of operators via their stability
Zenon Jan Jabłoński, Il Bong Jung, Carlos Kubrusly +1
This paper is concerned with the convergence of power sequences and stability of Hilbert space operators, where "convergence" and "stability" refer to weak, strong and norm topolog…
Forms of biisometric operators and biorthogonality
B. P. Duggal, C. S. Kubrusly
The paper proves two results involving a pair (A,B) of P-biisometric or (m,P)-biisometric Hilbert-space operators for arbitrary positive integer m and positive operator P. It is sh…
Weak Stability and Quasistability
C. S. Kubrusly, P. C. M. Vieira
It is known that weak l-sequential supercyclicity implies weak quasistability, and it is still unknown weather weak l-sequential supercyclicity implies weak stability, much less wh…
Weak l-sequential supercyclicity and weak quasistability
C. S. Kubrusly, B. P. Duggal
It is known that supercyclicity implies strong stability. It is not known whether weak l-sequential supercyclicity implies weak stability. In this paper we prove that weak l-sequen…
Restriction of Uniform Crossnorms
Carlos S. Kubrusly
Consider the space of operators on the tensors product of normed spaces and equipped with a uniform crossnorm Take the i…
Closed-range posinormal operators and their products
Paul Bourdon, Carlos Kubrusly, Trieu Le +1
We focus on two problems relating to the question of when the product of two posinormal operators is posinormal, giving (1) necessary conditions and sufficient conditions for posin…
Trace-Class and Nuclear Operators
Carlos S. Kubrusly
This paper explores the long journey from projective tensor products of a pair of Banach spaces, passing through the definition of nuclear operators still on the realm of projectiv…
Powers of posinormal Hilbert-space operators
Paul S. Bourdon, C. S. Kubrusly, Derek Thompson
A bounded linear operator on a Hilbert space is posinormal if there exists a positive operator such that . We show that if is posinormal…
Powers of posinormal operators
C. S. Kubrusly, P. C. M. Vieira, J. Zanni
Square of a posinormal operator is not necessarily posinormal But (i) powers of quasiposinormal operators are quasiposinormal and, under closed ranges assumption, powers of (ii)…
On Extensions of Bilinear Maps
C. S. Kubrusly
The paper deals with extension of bounded bilinear maps It gives a necessary and sufficient condition for extending a bounded bilinear map on the Cartesian product of subspaces…
Algebraic Tensor Products Revisited: Axiomatic Approach
C. S. Kubrusly
This is an expository paper on tensor products where the standard approaches for constructing concrete instances of algebraic tensor products of linear spaces, via quotient spaces…
Asymptotic limits, Banach limits, and Cesàro means
C. S. Kubrusly, B. P. Duggal
Every new inner product in a Hilbert space is obtained from the original one by means of a unique positive operator The first part of the paper is a survey on applications of su…
Boundedly Spaced Subsequences and Weak Dynamics
C. S. Kubrusly, P. C. M. Vieira
The purpose of this paper is to characterize weak supercyclicity for Hilbert-space contractions, which is shown to be equivalent to characterizing weak supercyclicity for unitary o…
Weakly Supercyclic Power Bounded Operators of Class C_{1.}
C. S. Kubrusly, B. P. Duggal
There is no supercyclic power bounded operator of class There exist, however, weakly l-sequentially supercyclic unitary operators We show that if i…
Biisometric operators and biorthogonal sequences
Carlos S. Kubrusly, Nhan Levan
It is shown that a pair of Hilbert space operators V and W such that V*W=I (called a biisometric pair) shares some common properties with unilateral shifts when orthonormal basis a…
Power bounded -left invertible operators
B. P. Duggal, C. S. Kubrusly
A Hilbert space operator $S\in\B$ is left -invertible by $T\in\B$ if is -isometric if…
Residual Spectrum of Power Bounded Operators
A. Mello, C. S. Kubrusly
The residual spectrum of a power bounded operator lies in the open unit disk.
Range-Kernel Complementation
C. S. Kubrusly
If a Banach-space operator has a complemented range, then its normed-space adjoint has a complemented kernel and the converse holds on a reflexive Banach space. It is also shown wh…
Denseness of Sets of Supercyclic Vectors
C. S. Kubrusly
The sets of strongly supercyclic, weakly l-sequentially supercyclic, weakly sequentially supercyclic, and weakly supercyclic vectors for an arbitrary normed-space operator are all…