FRG: Collaborative Research: Extremal Combinatorics and Flag Algebras

FRG：协作研究：极值组合学和标志代数

• 批准号: 2152498
• 负责人: Florian Pfender
• 金额: $ 37.01万
• 依托单位: University of Colorado at Denver-Downtown Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2152498&HistoricalAwards=false
• 关键词: FRG; Collaborative; Research; Extremal; Combinatorics

In extremal combinatorics one aims to find and characterize optimal members of a given class of mathematical objects. Those extremal objects often have unique properties and structures, giving insights in many mathematical fields. Over the last twenty years, several new techniques, many using the assistance of computers, have been extraordinarily successful in studying extremal objects. One of the recent powerful methods is based on the theory of flag algebras. This method enables researchers to translate extremal combinatorics questions into instances of semidefinite programs, which can then be explored with the help of a computer and academic as well as commercial software. This translation has led to recent breakthroughs on longstanding open questions. The method is versatile and can be applied in various settings such as graphs, hypergraphs, permutations, oriented graphs, point sets, embedded graphs, and phylogenetic trees. The aim of this focused research group is to resolve three prominent types of open questions by Erdős, Turán, and Zarankiewicz using these techniques.The three types of questions to be studied share the general flavor of generalized Turán problems, and solving them would have far reaching consequences. The first type are extremal hypergraph questions, the second type concerns finding maximum cuts in graphs with certain properties, and the third type are questions related to the crossing number of graphs. For all three, the use of flag algebras has recently led to significant progress but not to full solutions. This project will combine the expertise of the investigators with a concentrated effort and further method development to resolve these open questions. It is planned to find connections to more traditional methods such as the stability method and linear algebraic methods. A substantial number of students and early-career researchers will be trained and supported at the three institutions, and several focused workshops are planned.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在极值组合学中，人们的目标是找到并表征给定一类数学对象的最优成员。这些极端对象通常具有独特的性质和结构，在许多数学领域提供见解。在过去的20年里，一些新技术，其中许多是利用计算机的帮助，在研究极端物体方面取得了巨大的成功。最近的一个强大的方法是基于旗代数的理论。这种方法使研究人员能够将极值组合问题转化为半定程序的实例，然后可以在计算机和学术以及商业软件的帮助下进行探索。这种翻译导致了长期未决问题的最新突破。该方法是通用的，可以应用于各种设置，如图，超图，排列，定向图，点集，嵌入图，和系统发育树。这个研究小组的目标是使用这些技术解决Erdés，Turán和Zarankiewicz提出的三种突出的开放性问题。这三种待研究的问题具有广义Turán问题的一般特征，解决它们将产生深远的影响。第一类是极值超图问题，第二类是求图的最大割，第三类是求图的交叉数。对于这三种情况，旗代数的使用最近取得了重大进展，但没有完全解决。该项目将联合收割机结合调查人员的专门知识，集中努力，进一步发展方法，以解决这些悬而未决的问题。计划寻找与稳定性方法和线性代数方法等更传统方法的联系。大量的学生和早期职业研究人员将在这三个机构接受培训和支持，并计划举办几个重点研讨会。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。