Dissipative operators with finite dimensional damping

1982 ◽  
Vol 91 (3-4) ◽  
pp. 243-263 ◽  
Author(s):  
Harald Röh
Keyword(s):  
Separable Hilbert Space ◽  
Dissipative Operator ◽  
Finite Codimension ◽  
Spectral Mapping Theorem ◽  
Damped Wave Equation ◽  
Spectral Mapping ◽  
Dissipative Operators ◽  
Finite Dimensional ◽  
Maximal Dissipative Operator ◽  
Cayley Transformation

SynopsisLetG: ε(G)⊂ℋ → ℋ be a maximal dissipative operator with compact resolvent on a complex separable Hilbert space ℋ andT(t) be theCosemigroup generated byG. A spectral mapping theorem σ(T(t))\{0} = exp (tσ(G))/{0} together with a condition for 0 ε σ(T(t)) are proved if the set {xε ⅅ(G) | Re (Gx, x) = 0} has finite codimension in ε(G) and if some eigenvalue conditions forGare satisfied. Proofs are given in terms of the Cayley transformationT= (G+I)(G−I)−1ofG. The results are applied to the damped wave equationutt+ γutx+uxxxx+ ßuxx= 0, 0 ≦t< ∞ 0 <x< 1, β, γ ≧ 0, with boundary conditionsu(0,t) =ux(0,t) =uxx(1,t) =uxxx(1,t) = 0.

scholarly journals A spectral mapping theorem for the Weyl spectrum

1996 ◽  
Vol 38 (1) ◽  
pp. 61-64 ◽  
Author(s):  
Woo Young Lee ◽  
Sang Hoon Lee
Keyword(s):  
Hilbert Space ◽  
Linear Operators ◽  
Spectral Mapping Theorem ◽  
Spectral Mapping ◽  
Finite Multiplicity ◽  
Bounded Linear ◽  
Finite Dimensional ◽  
Weyl Spectrum ◽  
Isolated Points ◽  
Image Position

Suppose H is a Hilbert space and write ℒ(H) for the set of all bounded linear operators on H. If T ∈ ℒ(H) we write σ(T) for the spectrum of T; π0(T) for the set of eigenvalues of T; and π00(T) for the isolated points of σ(T) that are eigenvalues of finite multiplicity. If K is a subset of C, we write iso K for the set of isolated points of K. An operator T ∈ ℒ(H) is said to be Fredholm if both T−1(0) and T(H)⊥ are finite dimensional. The index of a Fredholm operator T, denoted by index(T), is defined by

scholarly journals A spectral mapping theorem for perturbed Ornstein–Uhlenbeck operators on L2(Rd)

2015 ◽  
Vol 268 (9) ◽  
pp. 2479-2524 ◽  
Author(s):  
Roland Donninger ◽  
Birgit Schörkhuber
Keyword(s):  
Spectral Mapping Theorem ◽  
Spectral Mapping

Joint Spectrum and the Spectral Mapping Theorem

1995 ◽  
pp. 73-80
Author(s):  
M. S. Livšic ◽  
N. Kravitsky ◽  
A. S. Markus ◽  
V. Vinnikov
Keyword(s):  
Spectral Mapping Theorem ◽  
Spectral Mapping ◽  
Joint Spectrum

Purity And Copurity in Systems of Linear Transformations

1976 ◽  
Vol 28 (4) ◽  
pp. 889-896
Author(s):  
Frank Zorzitto
Keyword(s):  
Vector Spaces ◽  
Finite Codimension ◽  
Linear Transformations ◽  
Complex Vector ◽  
Finite Dimensional ◽  
Quotient System

Consider a system of N linear transformations A1, … , AN: V → W, where F and IF are complex vector spaces. Denote it for short by (F, W). A pair of subspaces X ⊂ V, Y ⊂ W such that determines a subsystem (X, Y) and a quotient system (V/X, W/Y) (with the induced transformations). The subsystem (X, Y) is of finite codimension in (V, W) if and only if V/X and W / Y are finite-dimensional. It is a direct summand of (V, W) in case there exist supplementary subspaces P of X in F and Q of F in IF such that (P, Q) is a subsystem.

scholarly journals Residually finite dimensional algebras and polynomial almost identities

2020 ◽  
pp. 2250038
Author(s):  
Michael Larsen ◽  
Aner Shalev
Keyword(s):  
Lie Algebra ◽  
Finite Index ◽  
Open Group ◽  
Finite Codimension ◽  
Finite Dimensional Algebra ◽  
Nilpotent Ideal ◽  
Dimensional Algebra ◽  
Residually Finite ◽  
Finite Dimensional ◽  
Theoretic Problem

Let [Formula: see text] be a residually finite dimensional algebra (not necessarily associative) over a field [Formula: see text]. Suppose first that [Formula: see text] is algebraically closed. We show that if [Formula: see text] satisfies a homogeneous almost identity [Formula: see text], then [Formula: see text] has an ideal of finite codimension satisfying the identity [Formula: see text]. Using well known results of Zelmanov, we conclude that, if a residually finite dimensional Lie algebra [Formula: see text] over [Formula: see text] is almost [Formula: see text]-Engel, then [Formula: see text] has a nilpotent (respectively, locally nilpotent) ideal of finite codimension if char [Formula: see text] (respectively, char [Formula: see text]). Next, suppose that [Formula: see text] is finite (so [Formula: see text] is residually finite). We prove that, if [Formula: see text] satisfies a homogeneous probabilistic identity [Formula: see text], then [Formula: see text] is a coset identity of [Formula: see text]. Moreover, if [Formula: see text] is multilinear, then [Formula: see text] is an identity of some finite index ideal of [Formula: see text]. Along the way we show that if [Formula: see text] has degree [Formula: see text], and [Formula: see text] is a finite [Formula: see text]-algebra such that the probability that [Formula: see text] (where [Formula: see text] are randomly chosen) is at least [Formula: see text], then [Formula: see text] is an identity of [Formula: see text]. This solves a ring-theoretic analogue of a (still open) group-theoretic problem posed by Dixon,

scholarly journals A spectral mapping theorem for semigroups solving PDEs with nonautonomous past

2003 ◽  
Vol 2003 (16) ◽  
pp. 933-951 ◽  
Author(s):  
Genni Fragnelli
Keyword(s):  
Partial Differential Equations ◽  
Differential Equations ◽  
Spectral Mapping Theorem ◽  
Spectral Mapping ◽  
Partial Differential ◽  
The Stability

We prove a spectral mapping theorem for semigroups solving partial differential equations with nonautonomous past. This theorem is then used to give spectral conditions for the stability of the solutions of the equations.

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