Zobrazeno 1 - 10
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pro vyhledávání: '"Duggal, B. P."'
Autor:
Duggal, B. P., Kubrusly, C. S.
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 shown that if A and B are power bounded and the pair (A,B) is (m,P)-biis
Externí odkaz:
http://arxiv.org/abs/2401.16790
Autor:
Kubrusly, C. S., Duggal, B. P.
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-sequential supercyclicity implies weak quasistability. Corollaries concernin
Externí odkaz:
http://arxiv.org/abs/2306.08197
Autor:
Duggal, B. P.
Given commuting $d$-tuples $\mathbb{S}_i$ and $\mathbb{T}_i$, $1\leq i\leq 2$, Banach space operators such that the tensor products pair $(\mathbb{S}_1\otimes\mathbb{S}_2,\mathbb{T}_1\otimes\mathbb{T}_2)$ is strict $m$-isometric (resp., $\mathbb{S}_1
Externí odkaz:
http://arxiv.org/abs/2305.00898
Autor:
Duggal, B. P., Kim, I. H.
Given Hilbert space operators $P,T\in B(\H), P\geq 0$ invertible, $T$ is $(m,P)-$ expansive (resp., $(m,P)-$ isometric) for some positive integer $m$ if $\triangle_{T^*,T}^m(P)=\sum_{j=0}^m(-1)^j\left(\begin{array}{clcr}m\\j\end{array}\right){T^*}^jP
Externí odkaz:
http://arxiv.org/abs/2011.07847
Autor:
Duggal, B. P., Kim, I. H.
Given Hilbert space operators $A_i, B_i$, $i=1,2$, and $X$ such that $A_1$ commutes with $A_2$ and $B_!$ commutes with $B_2$, and integers $m, n\geq 1$, we say that the pairs of operators $(B_1,A_1)$ and $(B_2,A_2)$ are left-$(X, (m,n))$-symmetric, d
Externí odkaz:
http://arxiv.org/abs/2010.15474
Autor:
Duggal, B. P., Kim, I. H.
A Hilbert space operator $T\in B$ is $(m,P)$-expansive, for some positive integer $m$ and operator $P\in B$, if $\sum_{j=0}^m{(-1)^j\left(\begin{array}{clcr}m\\j\end{array}\right)T^{*j}PT^j}\leq 0$. No Drazin invertible operator $T$ can be $(m,I)$-ex
Externí odkaz:
http://arxiv.org/abs/2010.15480
Autor:
Kubrusly, C. S., Duggal, B. P.
Publikováno v:
Advances in Mathematical Sciences and Applications, Vol. 29, no. 1, pp. 145-170, Oct. 2020
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 such a technique, including a characterization of similarity to isometri
Externí odkaz:
http://arxiv.org/abs/2010.14740
Autor:
Duggal, B. P., Kim, I. H.
Publikováno v:
Demonstratio Math. 53(2020), 249-268
Given Hilbert space operators $T, S\in\B$, let $\triangle$ and $\delta\in B(\B)$ denote the elementary operators $\triangle_{T,S}(X)=(L_TR_S-I)(X)=TXS-X$ and $\delta_{T,S}(X)=(L_T-R_S)(X)=TX-XS$. Let $d=\triangle$ or $\delta$. Assuming $T$ commutes w
Externí odkaz:
http://arxiv.org/abs/2009.14438
Autor:
Duggal, B. P., Kim, I. H.
We use elementary algebraic properties of left, right multiplication operators to prove some deep structural properties of left $m$-invertible, $m$-isometric, $m$-selfadjoint and other related classes of Banach space operators, often adding value to
Externí odkaz:
http://arxiv.org/abs/2007.11368
Autor:
Kubrusly, C. S., Duggal, B. P.
Publikováno v:
Adv. Math. Sci. Appl. 30 (2021), no.2, 571-585
There is no supercyclic power bounded operator of class $C_{1{\textstyle\cdot}}.$ There exist, however, weakly l-sequentially supercyclic unitary operators$.$ We show that if $T$ is a weakly l-sequentially supercyclic power bounded operator of class
Externí odkaz:
http://arxiv.org/abs/2004.05253