Dimer-mediated interaction of gaps in lattice graphs

格子图中间隙的二聚体介导的相互作用

• 批准号: 0801625
• 负责人: Mihai Ciucu
• 金额: $ 12.75万
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0801625&HistoricalAwards=false
• 关键词: Dimer; mediated; interaction; gaps; lattice

This proposal is concerned with the asymptotic enumeration of dimer coverings of lattice graphs with holes. More specifically, using work of Fisher and Stephenson as its starting point, it studies how the total number of dimer coverings of the complement of the holes changes as the holes are shifted around on the lattice graph. The joint correlation of a collection of holes is a non-negative real number measuring this change, and is the central object of study of this proposal. In earlier work, the proposer proved that the correlation of holes on the hexagonal lattice is governed, for large separations between the holes, by a law closely resembling the superposition principle of electrostatics: If each hole is regarded as a point charge of magnitude given by the signed difference between the number of white and black vertices in it (in a fixed white-black coloring of the vertices in which each edge has oppositely colored endpoints), then, for large distances between the holes, their correlation is proportional to the exponential of the negative of the 2D electrostatic energy of the resulting system of charges. Other previous results concern two naturally defined fields that the proposer proved approach the electric field in the limit when the lattice spacing approaches zero. In the current project, the proposer presents a program organized in several inter-related groups comprising two dozen specific problems and conjectures. The bulk of this program is aimed at developing further the analogy to electrostatics, but the list includes also independent combinatorial problems, such as conjectures on tiling enumeration of new regions and problems arising in the study of card shufflings.This research is in the general area of Combinatorics. One of the goals of Combinatorics is to find efficient methods of studying how discrete collections of objects can be arranged. The behavior of discrete systems is extremely important to modern communications. For example, the design of large networks, such as those occurring in telephone systems, and the design of algorithms in computer science deal with discrete sets of objects, and this makes use of combinatorial research. The specific problems in this project are instances of the dimer model of statistical physics. A basic illustration of this is the real-world process (relevant to the study of of lubricants) of adsorption of a liquid, consisting of two-atom molecules---the dimers in the model---along the surface of a crystal, whose fixed atoms form a lattice pattern, with any two neighboring positions capable of holding one molecule, and any given crystal atom being involved in the adsorption of at most one molecule. The main issue in this setting is the asymptotic behavior of the quantities that are studied (speciffically, the number of different ways the surface of the crystal can be covered by molecules). In some of the instances we encounter, the usually more difficult problem of determining quantities exactly turns out to allow progress in the asymptotic study.

这一建议涉及到带孔格图的二聚体覆盖的渐近计数。更具体地说，它以Fisher和Stephenson的工作为起点，研究了当空穴在格图上移动时，空穴补集的二聚体覆盖总数是如何变化的。孔洞集合的联合相关性是衡量这种变化的非负实数，也是本方案研究的中心对象。在早期的工作中，提出者证明了，对于大的孔间距，六角形晶格上的孔的关联是由一个非常类似于静电学叠加原理的定律所支配的：如果每个孔被视为由其中的白色和黑色顶点的数目之间的符号差给出的数量级的点电荷(在其中每条边具有相反颜色的端点的固定的黑白颜色的顶点中)，那么，对于孔之间的大距离，它们的关联与所产生的电荷系统的2D静电能量的负指数成正比。其他以前的结果涉及两个自然定义的场，证明了当晶格间距接近零时，这两个自然定义的场接近极限电场。在目前的项目中，提出者提出了一个组织在几个相互关联的小组中的计划，包括24个具体的问题和猜想。本程序的主要目的是进一步发展与静电学的类比，但也包括独立的组合问题，如关于新区域的平铺计数的猜想和在研究洗牌时出现的问题。这项研究是在组合学的一般领域。组合学的目标之一是找到有效的方法来研究离散的对象集合如何排列。离散系统的行为对于现代通信来说是极其重要的。例如，大型网络的设计，如那些发生在电话系统中的网络，以及计算机科学中的算法设计，都涉及离散的对象集，这利用了组合研究。这个项目中的具体问题是统计物理的二聚体模型的例子。这方面的一个基本说明是液体在现实世界中的吸附过程(与润滑剂的研究有关)，液体由两个原子分子-模型中的二聚体--沿着晶体的表面吸附，其固定的原子形成晶格图案，任何两个相邻的位置都可以容纳一个分子，并且任何给定的晶体原子最多只参与一个分子的吸附。在这种情况下，主要的问题是所研究的量的渐近行为(具体地说，是指分子覆盖晶体表面的不同方式的数量)。在我们遇到的一些例子中，通常更困难的确定量的问题被证明是允许渐近研究取得进展的。