Generalized shift invariant systems
نویسندگان
چکیده
A countable collection X of functions in L2(IR ) is said to be a Bessel system if the associated analysis operator T ∗ X : L2(IR ) → `2(X) : f 7→ (〈f, x〉)x∈X is well-defined and bounded. A Bessel system is a fundamental frame if T ∗ X is injective and its range is closed. This paper considers the above two properties for a generalized shift-invariant system X. By definition, such a system has the form X = ∪j∈JYj , where each Yj is a shift-invariant system (i.e., is comprised of lattice translates of some function(s)) and J is a countable (or finite) index set. The definition is general enough to include wavelet systems, shift-invariant systems, Gabor systems, and many variations of wavelet systems such as quasi-affine ones and non-stationary ones. The main theme of this paper is the ‘fiberization’ of T ∗ X , which allows one to study the frame and Bessel properties of X via the spectral properties of a collection of finite-order Hermitian non-negative matrices. AMS (MOS) Subject Classifications: Primary 42C15, Secondary 42C30
منابع مشابه
Generalized shift-invariant systems and frames for subspaces
Given a real and invertible d×d matrix C, we define for k ∈ Zd a generalized translation operator TCk acting on f ∈ L 2(Rd) by (TCkf)(x) = f(x − Ck), x ∈ R . A generalized shift-invariant system is a system of the type {TCjkφj}j∈J,k∈Zd , where {Cj}j∈J is a countable collection of real invertible d×d matrices, and {φj}j∈J ⊂ L 2(Rd). Generalized shift-invariant systems contain the classical wavel...
متن کاملLI-YORKE CHAOTIC GENERALIZED SHIFT DYNAMICAL SYSTEMS
In this text we prove that in generalized shift dynamical system $(X^Gamma,sigma_varphi)$ for finite discrete $X$ with at least two elements, infinite countable set $Gamma$ and arbitrary map $varphi:GammatoGamma$, the following statements are equivalent: - the dynamical system $(X^Gamma,sigma_varphi)$ is Li-Yorke chaotic; - the dynamical system $(X^Gamma,sigma_varphi)$ has an scr...
متن کاملShift Invariant Spaces and Shift Preserving Operators on Locally Compact Abelian Groups
We investigate shift invariant subspaces of $L^2(G)$, where $G$ is a locally compact abelian group. We show that every shift invariant space can be decomposed as an orthogonal sum of spaces each of which is generated by a single function whose shifts form a Parseval frame. For a second countable locally compact abelian group $G$ we prove a useful Hilbert space isomorphism, introduce range funct...
متن کاملCOUNTEREXAMPLES IN CHAOTIC GENERALIZED SHIFTS
In the following text for arbitrary $X$ with at least two elements, nonempty countable set $Gamma$ we make a comparative study on the collection of generalized shift dynamical systems like $(X^Gamma,sigma_varphi)$ where $varphi:GammatoGamma$ is an arbitrary self-map. We pay attention to sub-systems and combinations of generalized shifts with counterexamples regarding Devaney, exact Dev...
متن کاملGeneralized Baer-Invariant of a Pair of Groups and Marginal Extension
In this paper, we give connection between the order of the generalized Baer-invariant of a pair of finite groups and its factor groups, when ? is considered to be the specific variety. Moreover, we give a necessary and sufficient condition in which the generalized Baer-invariant of a pair of groups can be embedded into the generalized Baer-invariant of pair of its factor groups.
متن کامل