Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 21 for “"Invariant subspaces"”.
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Stable invariant subspaces, reflexivity, and BMO
… the third part of the thesis we study the stable invariant subspaces of Hilbert-space operators. We prove that if T is an operator on an infinite dimensional Hilbert space whose spectrum and essential spectrum are both connected and whose Fredholm index is only 0 or 1, then the only nontrivial …
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On invariant subspaces of a normal operator
… operator which imply that the operator has invariant non-reducing subspaces. We were led to this study by the work of Halmos, Wermer, and Bram.
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Topics in the theory of invariant subspaces
Summary available: p. [4].
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Structure of Invariant Subspaces for Left-Invertible Operators on Hilbert Space
… is primarily concerned with studying the invariant subspaces of left-invertible, weighted shifts, with generalizations to left-invertible operators where applicable. The two main problems that are researched can be stated together as When does a weighted shift have the one-dimensional …
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On the geometry and parametrization of almost invariant subspaces and observer theory
… "On the geometry and parametrization of almost invariant subspaces and observer theory" I consider the set of almost conditioned invariant subspaces of fixed dimension for a given fixed linear finite-dimensional time-invariant observable control system in state space form. Almost conditioned …
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A Beurling Theorem for Noncommutative Hardy Spaces Associated with a Semifinite von Neumann Algebra with Various Norms
<p>We prove Beurling-type theorems for H-invariant spaces in relation to a semifinite von Neu-mann algebra M with a semifinite, faithful, normal tracial weight τ, using an extension of Arveson’s non-commutative Hardy space H-. First we prove a Beurling-Blecher-Labuschagne theorem for …
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Quantum Information Processing using the Power-of-SWAP
… group-theoretic methods to find the relevant invariant subspaces and associated vector-states. Some interesting patterns of states are found including onedimensional invariant subspaces spanned by W-states and the Hamming-weight preserving symmetry of the vectors spanning the various invariant …
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Several Problems Concerning Multivariate Functions and Associated Operators
… is provided, which uses special shift-invariant subspaces of the Hardy space. These shift-invariant subspaces are specific cases of Hilbert spaces that can be defined from Agler decompositions and their properties are analyzed. More specific results are obtained for certain classes of …
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A class of weighted Bergman spaces, reducing subspaces for multiple weighted shifts, and dilatable operators
… In Chapter 3 we will characterize the reducing subspaces of multiple weighted shifts. The reducing subspaces of the Bergman and the Dirichlet shift of multiplicity N are portrayed from this characterization. In Chapter 4 we will introduce the class of super-isometrically dilatable operators and …
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Lyapunov Exponents and Invariant Manifold for Random Dynamical Systems in a Banach Space
… the Lyapunov exponents and their associated invariant subspaces for infinite dimensional random dynamical systems in a Banach space, which are generated by, for example, stochastic or random partial differential equations. We prove a multiplicative ergodic theorem. Then, we use this theorem …
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Composite Multi resolution Analysis Wavelets
… in this setting along with a theory of shift invariant subspaces. We examine accuracy of this class of MRA wavelets and produce several examples of compactly support composite MRA wavelets.
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Properties of truncated Toeplitz operators
… Toeplitz operators: or TTOs) on backward shift invariant subspaces of the Hardy space of the unit disc. Specifically we discuss when the product of two TTOs is itself a TTO, finding an equivalent to a similar result of Brown and Halmos for ordinary Toeplitz operators. This leads us to …
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On Vector Sequence Transforms and Acceleration Techniques
… able to resolve approximations to low dimension invariant subspaces of <em>G</em> which contain large components of the error. When this occurs, simple weighted averages of iterates x,+|, i = 1 ,2 ,... k where k < n are used to produce iterates which contain approximately no error in the selfsame …
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Simulation-based Design with Polynomial Ridge Approximations
… for keeping multiple objectives constant through invariant subspaces are proposed. While the finding of invariant subspaces has been established for single objectives as a consequence of existing ridge approximation methods, the extension of this to multiple objectives is relatively new. Depending …
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Multivariable Interpolation Problems
… of Beurling-Lax representers for shift-invariant subspaces are required. Here we obtain these J-Beurling-Lax theorems by the state-space method for both settings. We see that the Krein-space geometry method is particularly simple in solving the interpolation problems when the …
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Dynamic gesture recognition using transformation invariant hand shape recognition
… outlined in this thesis uses transformation invariant subspaces created using Principal Component Analysis (PCA). These subspaces are created from a large vocabulary created in a systematic maimer using computer animation. In recognising dynamic gestures we utilise both hand shape and hand …
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Modeling and inference of the dynamics of spatiotemporally evolving systems using evolving gaussian processes
… able to derive the spatial distribution of the invariant subspaces of a system using a new clustering method. This information can be used for sensor placement and/or mobile agent path planning for robust inference of the state of the system using few measurements. We primarily demonstrate our …
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Optimisation of condition number for eigenstructure problems
… the assignability of spectrum of controllability subspaces (cs) based on an eigenvector approach and then develops a new pole assignment algorithm based on openloop/ closed-loop spectra as a practical application of this approach. In order to tackle the problem of measuring the skewness of angles …
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Bifurcations of maps: numerical algorithms and applications
… An aspect of this study is to identify the invariant objects and the local behaviour around them. This local information then needs to be assembled in a consistent way by means of geometric and topological arguments, to obtain a global picture of the system. At local bifurcations, the number …
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The Foundations of Infinite-Dimensional Spectral Computations
… of spectra, corresponding eigenvectors, and invariant subspaces, with convergence rates and error control. Finally, we analyse pseudospectra of pseudoergodic operators (a generalisation of random operators) on vector-valued $l^p$ spaces. All of the algorithms developed in this thesis are …
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