Analysis and Invariant Theory for Gelfand Pairs

提案：DMS-9970552主要研究者：Gail拉特克利夫、Chal Benson摘要。本研究计画是关于幂零李群的紧扩张的分析。一种说法是，当N上的可积K-不变函数在卷积下可交换时，紧李群K在幂零李群N上的作用产生一个Gelfand对。研究人员将继续他们对这种盖尔芬德对的研究，特别是他们对球函数的相关空间的研究，特别是当N是海森堡群时。具体目标包括进一步发展计算球函数及其特征值的算法，研究广义二项式系数的恒等式，描述Gelfand空间的拓扑结构，以及应用于Schwartz空间中的船体极小理想问题。傅立叶分析的技术，其根源可追溯到热传导问题的研究，是数学家武器库中最强大的工具之一。傅立叶分析中的一个重要构造是所谓的卷积积。在经典情形下，卷积具有重要的交换性。也就是说，可以重新排列乘积中因子的顺序，而不影响乘法的结果。然而，傅立叶分析有一个现代的和意义深远的推广，就像它的祖先与物理学中的重要问题联系在一起一样，其中卷积往往不是可交换的。在这类分析中的许多问题中，这是在被称为“李群”的对象框架中完成的，非交换性很自然地出现，无法避免，导致很大的技术困难。盖尔芬德对提供了一种在某些非对易情况下恢复对易性的简单性的方法。每个Gelfand对都提供了一个具有足够对称性的环境，以确保卷积乘积的可交换性。这样的对被命名为荣誉俄国数学家I。M. Gelfand和自20世纪50年代以来一直在研究。它们的有用性现在已经很好地建立在半单李群的非交换设置的分析。在过去的十年中，已经证明Gelfand对也出现在另一个非交换的环境中，即幂零李群。本研究的目标是系统的研究和数学分析这一类新的Gelfand对，包括显式计算的算法的发展。

Proposal: DMS-9970552Principal Investigators: Gail Ratcliff, Chal BensonAbstract. This research project concerns analysis on compact extensions of nilpotent Lie groups. One says that the action of a compact Lie group K on a nilpotent Lie group N yields a Gelfand pair when the integrable K-invariant functions on N commute under convolution. The investigators will continue their study of such Gelfand pairs, in particular their study of the associated space of spherical functions, especially when N is a Heisenberg group. Specific goals include further development of algorithms for computing spherical functions and their eigenvalues, study of identities for generalized binomial coefficients, a description of the topology of the Gelfand space, and applications to questions concerning hull minimal ideals in Schwartz spaces.The techniques of Fourier analysis, which traces its roots to the study of problems in heat conduction, are among the most powerful tools in the mathematician's arsenal. An important construction in Fourier analysis is the so-called convolution product. In the classical setting, convolution has the important property of commutativity. That is, one can rearrange the order of the factors in the product without affecting the result of the multiplication. There is, however, a modern and far-reaching generalization of Fourier analysis, like its ancestor linked to important problems in physics, in which convolution often fails to be commutative. In many problems in this type of analysis, which is done in the framework of objects known as "Lie groups," noncommutativity arises quite naturally and cannot be avoided, leading to great technical difficulties. Gelfand pairs provide a device to recover the simplicity of commutativity in certain noncommutative settings. Each Gelfand pair provides an environment with enough symmetry to ensure commutativity of the convolution product. Such pairs are named in honor of the Russian mathematician I. M. Gelfand and have been studied since the 1950s. Their usefulness is now well established in connection with analysis in the noncommutative setting of semi-simple Lie groups. In the past decade, it has been shown that Gelfand pairs also arise in another non-commutative setting, that of nilpotent Lie groups. The goals of this research concern the systematic study and mathematical analysis of this new class of Gelfand pairs, including the development of algorithms for explicit computations.