


Paper's Title:
Hyponormal and KQuasiHyponormal Operators On SemiHilbertian Spaces
Author(s):
Ould Ahmed Mahmoud Sid Ahmed and Abdelkader Benali
Mathematics Department,
College of Science,
Aljouf University,
Aljouf 2014,
Saudi Arabia.
Email:
sididahmed@ju.edu.sa
Mathematics Department, Faculty of
Science,
Hassiba Benbouali, University of Chlef,
B.P. 151 Hay Essalem, Chlef 02000,
Algeria.
Email:
benali4848@gmail.com
Abstract:
Let H be a Hilbert space and let A be a positive bounded operator on H. The semiinner product < uv>_{A}:=<Auv>, u,v ∈ H induces a seminorm  ._{A} on H. This makes H into a semiHilbertian space. In this paper we introduce the notions of hyponormalities and kquasihyponormalities 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 quasihyponormal operators. An operator T ∈ B_{A} (H) is said to be (A, k)quasihyponormal if
Paper's Title:
Some criteria for Subspacehypercyclicity of C_{0}semigroups
Author(s):
Mansooreh Moosapoor
Department of Mathematics,
Farhangian University, Tehran,
Iran.
Email: m.mosapour@cfu.ac.ir
mosapor110@gmail.com
Abstract:
We research subspacehypercyclic C_{0}semigroups in this paper. We present various types of subspacehypercyclicity criteria for C_{0}semigroups. Some of them are stronger than the criteria introduced before. Also, we state that if a C_{0}semigroup (T_{t}}_{t≥ 0} satisfies in any of them, then (T_{t}⊕T_{t}}_{t≥ 0} is subspacehypercyclic.
Paper's Title:
ANormal 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 Anormal operators in semiHilbertian 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.
Email:
margaritabustosgonzalez@uiowa.edu
The Ohio State University at Marion,
Department of Mathematics,
1465 Mount Vernon Avenue,
Marion, Ohio,
USA.
Email: 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 FermatTorricelli point of a triangle.
Paper's Title:
Preserver of Local Spectrum of Skewproduct Operators
Author(s):
Rohollah Parvinianzadeh^{1,*}, Meysam Asadipour^{2} and Jumakhan Pazhman^{3}
^{1}Department
of Mathematics,
College of Sciences,
University of Yasouj,
Yasouj, 7591874934,
Iran.
Email: r.parvinian@yu.ac.ir
^{2}Department
of Mathematics,
College of Sciences,
University of Yasouj,
Yasouj, 7591874934,
Iran.
Email: Asadipour@yu.ac.ir
^{3}Department
of Mathematics,
Ghor Institute of higher education,
Afghanistan.
Email: jumapazhman@gmail.com
Abstract:
Let H and K be infinitedimensional 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 σ_{T}(h) denote the local spectrum of T at h. For two nonzero vectors h_{0}∈ H and k_{0}∈ K, we show that if two maps φ_{1} and φ_{2} from B(H) into B(K) satisfy
σ_{φ1(T)φ2(S)*}(k_{0})= σ_{TS*}(h_{0}})
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 φ_{1}(T) = PTQ and φ_{2}(T)^{*} =Q^{1}T^{*}P^{1} for all T ∈ B(H). Also, we obtain some interesting results in this direction.
Paper's Title:
Boundedness for VectorValued Multilinear Singular Integral Operators on TriebelLizorkin 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 vectorvalued multilinear operators associated to certain fractional singular integral operators on TriebelLizorkin space are obtained. The operators include CalderónZygmund singular integral operator and fractional integral operator.
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