论文标题
在波浪包空间的Banach框架的近乎正交性上
On near orthogonality of the Banach frames of the wave packet spaces
论文作者
论文摘要
在解决科学,工程或纯数学问题时,通常需要通过在时间和频域中以一种或另一种方式定位的少量函数的线性组合来近似给定类的功能。在过去的七十年左右的时间里,已经开发了一系列局部功能的系统,以允许分解和合成各个类别的功能。此类系统最突出的例子是Gabor函数,小波,山脊,曲线,剪切和波原子。最近,我们引入了一个准巴纳赫空间(我们称之为波数据包空间)的一家家族,其中包含所有这些类别的功能,其元素在上述系统之一中具有稀疏扩展的功能,并为它们提供了Banach框架并提供了原子分解。在此,我们证明了波数据包空间的Banach框架和一组原子,或者更具体地说,它们靠近正交。我们认为,波数据包系统的良好本地化(即使在希尔伯特空间中的框架中也无法理所当然的属性,更不用说Banach Space的框架都将其视为理所当然,这将铺平道路,除其他方面,因为它们用于代表Banach Space上的傅立叶积分运算符,这是由Galerkin方法稀疏和结构良好的矩阵。反过来,这应该允许人们设计有效的计算机程序,以在二维流形上求解相应的操作员方程。
In solving scientific, engineering or pure mathematical problems one is often faced with a need to approximate the function of a given class by the linear combination of a preferably small number of functions that are localised one way or another both in the time and frequency domain. Over the last seventy years or so a range of systems of thus localised functions have been developed to allow the decomposition and synthesis of functions of various classes. The most prominent examples of such systems are Gabor functions, wavelets, ridgelets, curvelets, shearlets and wave atoms. We recently introduced a family of quasi-Banach spaces -- which we called wave packet spaces -- that encompasses all those classes of functions whose elements have sparse expansions in one of the above-mentioned systems, supplied them with Banach frames and provided their atomic decompositions. Herein we prove that the Banach frames and sets of atoms of the wave packet spaces are well localised or, more specifically, that they are near orthogonal. We believe that good localisation of the wave packet systems -- a property of paramount importance that can't be taken for granted even for frames in Hilbert spaces, let alone Banach spaces -- will pave the way, among other things, for their use for representing Fourier integral operators on Banach spaces by sparse and well structured matrices by the Galerkin method. This, in its turn, should allow one to design efficient computer programmes for solving corresponding operator equations on two-dimensional manifolds.