Analysis and geometry of metric spaces with applications in geometric group theory and topology.

分析、几何和群论是数学的三个主要经典领域。分析学研究空间的局部性质，几何学关注的是空间的整体结构，而群论则想知道空间的对称性。度量空间是所有三个潜在感兴趣的对象的一个例子，并且这个建议涉及一致离散度量空间。这样的空间，其中任何两点之间的距离永远不会小于某个固定的数字（想想黑夜中的星星）从分析的角度看，似乎没有足够的局部结构使它们变得有趣，但就像如果我们从很远的地方看，一群星星开始显示出错综复杂的形状一样（这就是我们观察星系的方式），如果我们在大尺度上研究离散度规空间，它将成为一个有趣的分析对象。格罗莫夫和罗伊提供了一个具体的方案来使用这个简单的洞察力;其结果，粗几何，现在是一个既定的工具，并已特别成功时，应用于离散群体。在一个群生成的群中，每个元素都可以用有限的字母表写成一个词，短词可以被认为靠近单位元素，长词可以被认为远离单位元素，这就产生了一个自然的度量，它赋予群一个均匀的（从每一点看都一样）和对称的形状（整个群提供了这个空间的对称性）。这个空间可以通过约化的C*-代数的性质来解析地描述，并且在这个数学领域中的一些最重要的问题，如鲍姆-康纳斯猜想，都是源于对理解这个代数结构的渴望。这个建议源于我们的发现，度量空间，局部类似于在粗几何意义上的群体与群体共享许多有趣的分析性质。此外，我们已经开发了一个不变量，使我们能够说，当度量空间是足够相似的一组。我们的主要新思想，部分平移结构的度量空间，捕捉关键的组合性质的左，右multiplication行动的一个组本身，并提供了一种方法，编码这些属性在一个新的C*-代数，部分平移代数，我们与度量空间。一个统一的战略，这个建议是部分平移结构，部分平移C*-代数和我们的不变量的发展，提供新的路线的重要的突出问题的攻击。一个困难和研究较多的问题是当度量空间允许一致嵌入到希尔伯特空间或群。这样的嵌入允许人们控制空间的大尺度几何形状：我们将空间与已知几何形状的物体进行比较，在第一种情况下，或者在第二种情况下，已知对称性。我们将进一步发展我们的技术，以构建新的反例粗鲍姆-康纳斯猜想，这是一个重要的组织原则，为大量的研究之间的接口的分析和几何的群体和度量空间。我们的方法也将提供见解瓦莱特猜想，这是一个重要的开放问题，在几何群论。这个建议是及时的，雄心勃勃的和苛刻的，并放置在一个令人兴奋的，迅速发展和竞争激烈的数学领域。

Analysis, geometry and group theory are three of the main classical areas of mathematics. Analysis studies local properties of a space, geometry is concerned with its overall structure, while group theory wants to know the space's symmetries. A metric space is an example of an object which is potentially of interest to all three, and this proposal is concerned with uniformly discrete metric spaces. Such spaces, where the distance between any two points is never smaller than some fixed number (think of stars on a dark night) do not seem to have enough local structure to make them interesting from the point of view of analysis, but just as a collection of stars begins to display an intricate shape if we look at it from a large distance (this is how we observe galaxies), a discrete metric space becomes an interesting analytic object if we study it on the large scale. Gromov and Roe provided a concrete scheme for using this simple insight; the result, coarse geometry, is now an established tool, and has been particularly successful when applied to discrete groups. In a finitely generated group, where every element can be written as a word using a finite alphabet, short words can be regarded as being close to the identity element, and long words far away from it. This leads to a natural metric, which gives the group a shape that is homogeneous (looks the same from every point) and symmetric (the whole group provides symmetries of this space). This space can be described analytically through the properties of the reduced C*-algebra, and some of the most important questions in this area of mathematics, like the Baum-Connes conjecture, arise from desire to understand the structure of this algebra. This proposal arises from our discovery that metric spaces which locally resemble groups in the coarse-geometric sense share with groups a lot of interesting analytic properties. Moreover, we have developed an invariant that allows us to say when a metric space is sufficiently similar to a group. Our main new idea, the partial translation structure on a metric space, captures the key combinatorial properties of the left and right mulitplication action of a group on itself and provides a method of encoding those properties in a new C*-algebra, the partial translation algebra, that we associate with a metric space. A unifying strategy of this proposal is the development of partial translation structures, partial translation C*-algebras and our invariant to provide new routes of attack on important outstanding problems. A difficult and much studied question is when a metric space admits a uniform embedding into a Hilbert space or a group. Such an embedding allows one to control the large scale geometry of a space: we compare the space with an object of known geometry, in the first case, or known symmetry, in the second. We will further develop our techniques to construct new counterexamples to the coarse Baum-Connes conjecture, which is an important organising principle for a large body of research on the interface between the analysis and geometry of groups and metric spaces. Our approach will also provide insights into the Valette conjecture, which is an important open question in geometric group theory. This proposal is timely, ambitious and demanding, and is placed in an exciting, rapidly developing and competitive area of mathematics.