Combinatorial aspects of representation theory and geometry

表示论和几何的组合方面

• 批准号: RGPIN-2016-04872
• 负责人: Thomas, Hugh
• 金额: $ 2.4万
• 依托单位: Université du Québec à Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=666761
• 关键词: Combinatorial; aspects; representation; theory; geometry

Combinatorics is the study of discrete arrangements, such as the different ways of dividing n balls among k different boxes. Often, it is possible to understand such discrete arrangements much better than we could hope to understand the continuously changing phenomena that we typically encounter in real life. However, as it turns out, discrete structures can have important implications, in real life, and also in other areas of mathematics. My proposal consists of using combinatorial techniques to understand mathematical structures which arise in algebra and physics.***The physics I am interested in is the problem of calculating scattering amplitudes. This is quite a natural and fundamental problem. We throw a collection of particles at each other. They interact somehow, and then zoom off. We want to know the outcome. Because we are in a quantum setting, the outcome is uncertain, but there are different possibilities, to each of which a probability can be assigned. The usual approach to calculating scattering amplitudes is to write down what is typically a very large number of Feynman diagrams which encode the possible interactions among the particles, and then add up a contribution from each. It is a surprising fact that when we do this, the answer is simple and symmetrical in a way that the individual terms being summed are not. This suggests that the Feynman diagram approach might be obscuring the fundamental simplicity of what is happening. A new approach to scattering amplitudes has been developed by Nima Arkani-Hamed and a team of collaborators. In their approach, Feynman diagrams are replaced by something which the physicists call "on-shell diagrams", but which had already been studied by Alex Postnikov and other mathematicians under the name of "plabic graphs". By studying the combinatorics and geometry associated to these plabic graphs, in collaboration with Nima Arkani-Hamed and Jaroslav Trnka, I hope to come to a better understanding of this new approach. ***Combinatorics can also be applied in algebraic settings. One way to do this is to start from a combinatorial system and associate some kind of algebra to it. Our understanding of the combinatorics will likely help us to understand such algebras. It is also possible that powerful algebraic tools may then also improve our understanding of the combinatorics from which we set out. To be a bit more specific, I am interested in links between the combinatorics of reflection groups (a generalization of permutations) and the representation theory of preprojective algebras and their quotients. **

组合学是对离散排列的研究，例如在 k 个不同的盒子中划分 n 个球的不同方式。 通常，对这种离散排列的理解可能比我们希望理解的在现实生活中通常遇到的不断变化的现象要好得多。 然而，事实证明，离散结构在现实生活以及数学的其他领域都可以产生重要的影响。 我的建议包括使用组合技术来理解代数和物理学中出现的数学结构。***我感兴趣的物理学是计算散射幅度的问题。 这是一个非常自然和基本的问题。 我们向对方扔出一组粒子。 他们以某种方式相互作用，然后缩小。 我们想知道结果。 因为我们处于量子环境中，结果是不确定的，但存在不同的可能性，每种可能性都可以分配一个概率。 计算散射振幅的常用方法是写下通常非常大量的费曼图，这些费曼图编码了粒子之间可能的相互作用，然后将每个粒子的贡献相加。 令人惊讶的事实是，当我们这样做时，答案是简单且对称的，而求和的各个项则不然。 这表明费曼图方法可能掩盖了正在发生的事情的基本简单性。 Nima Arkani-Hamed 和合作者团队开发了一种新的散射振幅方法。 在他们的方法中，费曼图被物理学家称为“壳上图”的东西所取代，但亚历克斯·波斯特尼科夫和其他数学家已经以“平面图”的名义进行了研究。 通过与 Nima Arkani-Hamed 和 Jaroslav Trnka 合作研究与这些平面图相关的组合学和几何学，我希望能够更好地理解这种新方法。 ***组合学也可以应用于代数设置。 实现此目的的一种方法是从组合系统开始并将某种代数与其关联。 我们对组合学的理解可能会帮助我们理解这样的代数。 强大的代数工具也有可能提高我们对组合数学的理解。 更具体地说，我对反射群的组合学（排列的推广）与预投影代数及其商的表示论之间的联系感兴趣。 **