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Paper's Title:
Hyponormal and K-Quasi-Hyponormal Operators On Semi-Hilbertian Spaces
Author(s):
Ould Ahmed Mahmoud Sid Ahmed and Abdelkader Benali
Mathematics Department,
College of Science,
Aljouf University,
Aljouf 2014,
Saudi Arabia.
E-mail:
sididahmed@ju.edu.sa
Mathematics Department, Faculty of
Science,
Hassiba Benbouali, University of Chlef,
B.P. 151 Hay Essalem, Chlef 02000,
Algeria.
E-mail:
benali4848@gmail.com
Abstract:
Let H be a Hilbert space and let A be a positive bounded operator on H. The semi-inner product < u|v>A:=<Au|v>, u,v ∈ H induces a semi-norm || .||A on H. This makes H into a semi-Hilbertian space. In this paper we introduce the notions of hyponormalities and k-quasi-hyponormalities for operators on semi Hilbertian space (H,||.||A), based on the works that studied normal, isometry, unitary and partial isometries operators in these spaces. Also, we generalize some results which are already known for hyponormal and quasi-hyponormal operators. An operator T ∈ BA (H) is said to be (A, k)-quasi-hyponormal if
Paper's Title:
Some criteria for Subspace-hypercyclicity of C0-semigroups
Author(s):
Mansooreh Moosapoor
Department of Mathematics,
Farhangian University, Tehran,
Iran.
E-mail: m.mosapour@cfu.ac.ir
mosapor110@gmail.com
Abstract:
We research subspace-hypercyclic C0-semigroups in this paper. We present various types of subspace-hypercyclicity criteria for C0-semigroups. Some of them are stronger than the criteria introduced before. Also, we state that if a C0-semigroup (Tt}t≥ 0 satisfies in any of them, then (Tt⊕Tt}t≥ 0 is subspace-hypercyclic.
Paper's Title:
A-Normal Operators In Semi Hilbertian Spaces
Author(s):
A. Saddi
Department of Mathematics,
College of Education for Girls in Sarat Ebeidah 61914, Abha,
King Khalid University
Saudi Arabia
adel.saddi@fsg.rnu.tn
Abstract:
In this paper we study some properties and inequalities of A-normal operators in semi-Hilbertian spaces by employing some known results for vectors in inner product spaces. We generalize also most of the inequalities of (α,β)-normal operators discussed in Hilbert spaces [7].
Paper's Title:
Sharp Inequalities Between Hölder and Stolarsky Means of Two Positive Numbers
Author(s):
M. Bustos Gonzalez and A. I. Stan
The University of Iowa,
Department of Mathematics,
14 MacLean Hall,
Iowa City, Iowa,
USA.
E-mail:
margarita-bustosgonzalez@uiowa.edu
The Ohio State University at Marion,
Department of Mathematics,
1465 Mount Vernon Avenue,
Marion, Ohio,
USA.
E-mail: stan.7@osu.edu
Abstract:
Given any index of the Stolarsky means, we find the greatest and least indexes of the H\"older means, such that for any two positive numbers, the Stolarsky mean with the given index is bounded from below and above by the Hölder means with those indexes, of the two positive numbers. Finally, we present a geometric application of this inequality involving the Fermat-Torricelli point of a triangle.
Paper's Title:
Preserver of Local Spectrum of Skew-product Operators
Author(s):
Rohollah Parvinianzadeh1,*, Meysam Asadipour2 and Jumakhan Pazhman3
1Department
of Mathematics,
College of Sciences,
University of Yasouj,
Yasouj, 75918-74934,
Iran.
E-mail: r.parvinian@yu.ac.ir
2Department
of Mathematics,
College of Sciences,
University of Yasouj,
Yasouj, 75918-74934,
Iran.
E-mail: Asadipour@yu.ac.ir
3Department
of Mathematics,
Ghor Institute of higher education,
Afghanistan.
E-mail: jumapazhman@gmail.com
Abstract:
Let H and K be infinite-dimensional complex Hilbert spaces, and B(H) (resp. B(K)) be the algebra of all bounded linear operators on H (resp. on K). For an operator T∈ B(H) and a vector h∈ H, let σT(h) denote the local spectrum of T at h. For two nonzero vectors h0∈ H and k0∈ K, we show that if two maps φ1 and φ2 from B(H) into B(K) satisfy
σφ1(T)φ2(S)*(k0)= σTS*(h0})
for all T, S ∈ B(H), and their range containing all operators of rank at most two, then there exist bijective linear maps P : H→ K and Q : K→ H such that φ1(T) = PTQ and φ2(T)* =Q-1T*P-1 for all T ∈ B(H). Also, we obtain some interesting results in this direction.
Paper's Title:
Boundedness for Vector-Valued Multilinear Singular Integral Operators on Triebel-Lizorkin Spaces
Author(s):
Liu Lanzhe
College of Mathematics
Changsha University of Science and Technology,
Changsha 410077,
P.R. of China.
lanzheliu@263.net
Abstract:
In this paper, the boundedness for some vector-valued multilinear operators associated to certain
fractional singular integral operators on Triebel-Lizorkin space are obtained. The operators include Calderón-Zygmund
singular integral operator and fractional integral operator.
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