On n-quasi-m-isometric operators

2016 ◽  
Vol 09 (04) ◽  
pp. 1650073 ◽  
Author(s):  
Salah Mecheri ◽  
T. Prasad
Keyword(s):  
Hilbert Space ◽  
Matrix Representation ◽  
Isometric Operator ◽  
Basic Properties

We introduce the class of [Formula: see text]-quasi-[Formula: see text]-isometric operators on Hilbert space. This generalizes the class of [Formula: see text]-isometric operators on Hilbert space introduced by Agler and Stankus. An operator [Formula: see text] is said to be [Formula: see text]-quasi-[Formula: see text]-isometric if [Formula: see text] In this paper [Formula: see text] matrix representation of a [Formula: see text]-quasi-[Formula: see text]-isometric operator is given. Using this representation we establish some basic properties of this class of operators.

scholarly journals Quasi-posinormal operators

2010 ◽  
Vol 7 (3) ◽  
pp. 1282-1287
Author(s):  
Baghdad Science Journal
Keyword(s):  
Hilbert Space ◽  
Normal Operator ◽  
Basic Properties ◽  
Hyponormal Operators ◽  
The Relationship

In this paper, we introduce a class of operators on a Hilbert space namely quasi-posinormal operators that contain properly the classes of normal operator, hyponormal operators, M–hyponormal operators, dominant operators and posinormal operators . We study some basic properties of these operators .Also we are looking at the relationship between invertibility operator and quasi-posinormal operator .

scholarly journals Dirac structures on Hilbert spaces

1999 ◽  
Vol 22 (1) ◽  
pp. 97-108 ◽  
Author(s):  
A. Parsian ◽  
A. Shafei Deh Abad
Keyword(s):  
Hilbert Space ◽  
Linear Operator ◽  
Hilbert Spaces ◽  
Smooth Manifold ◽  
Real Hilbert Space ◽  
Dirac Structure ◽  
Dirac Structures ◽  
Basic Properties ◽  
Hilbert Subspace ◽  
Densely Defined

For a real Hilbert space(H,〈,〉), a subspaceL⊂H⊕His said to be a Dirac structure onHif it is maximally isotropic with respect to the pairing〈(x,y),(x′,y′)〉+=(1/2)(〈x,y′〉+〈x′,y〉). By investigating some basic properties of these structures, it is shown that Dirac structures onHare in one-to-one correspondence with isometries onH, and, any two Dirac structures are isometric. It is, also, proved that any Dirac structure on a smooth manifold in the sense of [1] yields a Dirac structure on some Hilbert space. The graph of any densely defined skew symmetric linear operator on a Hilbert space is, also, shown to be a Dirac structure. For a Dirac structureLonH, everyz∈His uniquely decomposed asz=p1(l)+p2(l)for somel∈L, wherep1andp2are projections. Whenp1(L)is closed, for any Hilbert subspaceW⊂H, an induced Dirac structure onWis introduced. The latter concept has also been generalized.

scholarly journals m-ISOMETRIC OPERATORS ON BANACH SPACES

2010 ◽  
Vol 03 (01) ◽  
pp. 1-19 ◽  
Author(s):  
Ould Ahmed Mahmoud Sid Ahmed
Keyword(s):  
Banach Space ◽  
Hilbert Space ◽  
Banach Spaces ◽  
Natural Generalization ◽  
Basic Properties

We introduce the class of m-isometric operators on Banach spaces. This generalizes to Banach space the m-isometric operators on Hilbert space introduced by Agler and Stankus. We establish some basic properties and we introduce the notion of m-invertibility as a natural generalization of the invertibility on Banach spaces.

(A-n) – Potent operators on Hilbert space

2019 ◽  
pp. 7-12
Author(s):  
Laith K. Shaakir ◽  
Elaf S. Abdulwahid ◽  
Anas A. Hijab
Keyword(s):  
Hilbert Space ◽  
Positive Integer ◽  
Complex Hilbert Space ◽  
Integer Number ◽  
Basic Properties ◽  
New Class

In this paper, we introduce a new class of operators on a complex Hilbert space which is called (A-n)-potent operator. An operator is called (A-n)-potent operator if where is positive integer number greater than or equal 2. We investigate some basic properties of such operators and study the relation between (A-n)-potent operators and some kinds of operators.

Quasi-Multipliers and Embeddings of Hilbert C*-Bimodules

1994 ◽  
Vol 46 (06) ◽  
pp. 1150-1174 ◽  
Author(s):  
Lawrence G. Brown ◽  
James A. Mingo ◽  
Nien-Tsu Shen
Keyword(s):  
Hilbert Space ◽  
Hilbert Spaces ◽  
Relative Position ◽  
Doctoral Dissertation ◽  
Basic Properties ◽  
The Third ◽  
Slight Generalization

Abstract This paper considers Hilbert C*-bimodules, a slight generalization of imprimitivity bimodules which were introduced by Rieffel [20]. Brown, Green, and Rieffel [7] showed that every imprimitivity bimodule X can be embedded into a certain C*-algebra L, called the linking algebra of X. We consider arbitrary embeddings of Hilbert C*-bimodules into C*-algebras; i.e. we describe the relative position of two arbitrary hereditary C*-algebras of a C*-algebra, in an analogy with Dixmier's description [10] of the relative position of two subspaces of a Hilbert space. The main result of this paper (Theorem 4.3) is taken from the doctoral dissertation of the third author [22], although the proof here follows a different approach. In Section 1 we set out the definitions and basic properties (mostly folklore) of Hilbert C*-bimodules. In Section 2 we show how every quasi-multiplier gives rise to an embedding of a bimodule. In Section 3 we show that , the enveloping C*-algebra of the C*-algebraA with its product perturbed by a positive quasi-multiplier , is isomorphic to the closure (Proposition 3.1). Section 4 contains the main theorem (4.3), and in Section 5 we explain the analogy with the relative position of two subspaces of a Hilbert spaces and present some complements.

scholarly journals Spectral properties of square hyponormal operators

Filomat ◽  
2019 ◽  
Vol 33 (15) ◽  
pp. 4845-4854
Author(s):  
Muneo Chō ◽  
Dijana Mosic ◽  
Biljana Nacevska-Nastovska ◽  
Taiga Saito
Keyword(s):  
Hilbert Space ◽  
Linear Operator ◽  
Bounded Linear Operator ◽  
Spectral Properties ◽  
Complex Hilbert Space ◽  
Hyponormal Operator ◽  
Bounded Linear ◽  
Basic Properties ◽  
Hyponormal Operators ◽  
Eigen Values

In this paper, we introduce a square hyponormal operator as a bounded linear operator T on a complex Hilbert space H such that T2 is a hyponormal operator, and we investigate some basic properties of this operator. Under the hypothesis ?(T) ? (-?(T)) ? {0}, we study spectral properties of a square hyponormal operator. In particular, we show that if z and w are distinct eigen-values of T and x,y ? H are corresponding eigen-vectors, respectively, then ?x,y? = 0. Also, we define nth hyponormal operators and present some properties of this kind of operators.

scholarly journals QUANTUM GROUP-TWISTED TENSOR PRODUCTS OF C*-ALGEBRAS

2014 ◽  
Vol 25 (02) ◽  
pp. 1450019 ◽  
Author(s):  
RALF MEYER ◽  
SUTANU ROY ◽  
STANISŁAW LECH WORONOWICZ
Keyword(s):  
Hilbert Space ◽  
Tensor Product ◽  
Quantum Group ◽  
Quantum Groups ◽  
Tensor Products ◽  
Group Representations ◽  
Basic Properties ◽  
C Algebras ◽  
Twisted Tensor Product

We put two C*-algebras together in a noncommutative tensor product using quantum group coactions on them and a bicharacter relating the two quantum groups that act. We describe this twisted tensor product in two equivalent ways, based on certain pairs of quantum group representations and based on covariant Hilbert space representations, respectively. We establish basic properties of the twisted tensor product and study some examples.

Polaroid operators and Weyl type theorems

2019 ◽  
Vol 13 (07) ◽  
pp. 2050123
Author(s):  
Salah Mecheri ◽  
Naim L. Braha
Keyword(s):  
Hilbert Space ◽  
Analytic Function ◽  
Complex Hilbert Space ◽  
Basic Properties ◽  
Polaroid Operators ◽  
Weyl Type Theorems

Let [Formula: see text] be a [Formula: see text]-quasiposinormal operator on a complex Hilbert space [Formula: see text]. In this paper, we give basic properties for [Formula: see text] and we show that a [Formula: see text]-quasiposinormal operator [Formula: see text] is polaroid. We also prove that all Weyl type theorems (generalized or not) hold and are equivalent for [Formula: see text], where [Formula: see text] is an analytic function defined on a neighborhood of [Formula: see text].

A Matrix Representation of a Pair of Projections in a Hilbert Space

1971 ◽  
Vol 14 (1) ◽  
pp. 35-44 ◽  
Author(s):  
R. Giles ◽  
H. Kummer
Keyword(s):  
Hilbert Space ◽  
Scalar Product ◽  
Matrix Representation ◽  
Complex Hilbert Space ◽  
Scalar Multiplication ◽  
Image Position

Let H be a complex Hilbert space and let K = H ⊕ H. Then K can be identified with the set of all column matricesequipped with componentwise addition and scalar multiplication and the scalar product

scholarly journals Unitary Boundary Pairs for Isometric Operators in Pontryagin Spaces and Generalized Coresolvents

2021 ◽  
Vol 15 (2) ◽  
Author(s):  
D. Baidiuk ◽  
V. Derkach ◽  
S. Hassi
Keyword(s):  
Hilbert Space ◽  
Schur Functions ◽  
Characteristic Functions ◽  
General Notion ◽  
Pontryagin Space ◽  
Isometric Operator ◽  
Pontryagin Spaces ◽  
Alternative Approach ◽  
Boundary Triple ◽  
Space Case

AbstractAn isometric operator V in a Pontryagin space $${{{\mathfrak {H}}}}$$ H is called standard, if its domain and the range are nondegenerate subspaces in $${{{\mathfrak {H}}}}$$ H . A description of coresolvents for standard isometric operators is known and basic underlying concepts that appear in the literature are unitary colligations and characteristic functions. In the present paper generalized coresolvents of non-standard Pontryagin space isometric operators are described. The methods used in this paper rely on a new general notion of boundary pairs introduced for isometric operators in a Pontryagin space setting. Even in the Hilbert space case this notion generalizes the earlier concept of boundary triples for isometric operators and offers an alternative approach to study operator valued Schur functions without any additional invertibility requirements appearing in the ordinary boundary triple approach.

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