Conformal Dynamics

共形动力学

• 批准号: 9704368
• 负责人: Gregory Swiatek
• 金额: $ 7.59万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-07-01 至 2000-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9704368&HistoricalAwards=false
• 关键词: Conformal; Dynamics

Summary: The project concentrates on two problems, one in real conformal dynamics and one in complex. The real part is about poly-modal mappings of the interval, i.e., smooth maps of the interval with finitely many turning points; a map with only one turning point is a unimodal transformation. Here the goal of the proposal can be very simply summarized: what can be carried ovep from the unimodal theory, so successful in the last five years, to the poly-modal case? The complex problem is about Siegel disks. Siegel disks are sub-domains of a complex dynamical system, usually a rational map, where the dynamics can be brought to a linear rotation by a holomorphic change of coordinates. A lot of mystery has surrounded the boundaries of Siegel disks. First insights were gained only in the mid-eighties with the work of M. Herman. The project proposes to refine some of the analytic tools used in his work to get more information. Finally, some research is proposed in areas that do not belong to conformal dynamics, namely induced hyperbolicity in two-dimensional systems and combinatorial optimization viewed as an applied problem in a very high-dimensional setting. Unlike the rather conservative goals set in the first two problems, these should be termed exploratory research. The proposal is concerned mostly with one-dimensional dynamical systems. Such systems generally come from models which describe time changes of an observable parameter. Year-to-year changes in a single animal population lead to this type of system, provided one assumes that the population in the next year is determined by the current-year count and no other factors. Some examples that will be studied, notably the logistic family, grew from models of interest in diverse areas including physics, ecmnomics and ecology. The questions that the proposal addresses, when translated back to these models, are related to the long-term behavior and stability of such systems. For example: will the population tend to a long-t erm equilibrium? The proposal is also concerned with the problem of combinatorial optimization. Practical problems such as the "traveling salesman" problem are believed by many experts to be intractable if one insists on the exact solution. The proposal will examine a new approach based on the ideas of thermodynamics with the goal of getting high-performance approximate solutions.

摘要：该项目集中在两个问题，一个在真实的共形动力学和一个在复杂的。 真实的部分是关于区间的多峰映射，即，具有多个转折点的区间的光滑映射;只有一个转折点的映射是单峰变换。 在这里，该提案的目标可以非常简单地概括为：从过去五年来如此成功的单峰理论到多峰情况，可以进行什么？ 这个复杂的问题是关于西格尔圆盘的。 西格尔圆盘是一个复杂动力系统的子域，通常是一个有理映射，其中的动力学可以通过坐标的全纯变化而变成线性旋转。 西格尔圆盘的边界有很多谜团。 直到80年代中期，随着M。赫尔曼。 该项目建议改进他工作中使用的一些分析工具，以获得更多信息。 最后，提出了一些不属于共形动力学领域的研究，即二维系统中的诱导双曲性和被视为非常高维环境中的应用问题的组合优化。 与前两个问题中设定的相当保守的目标不同，这些应该被称为探索性研究。 该建议主要涉及一维动力系统。 这样的系统通常来自描述可观察参数的时间变化的模型。 一个动物种群的逐年变化导致了这种类型的系统，假设下一年的种群是由当年的数量决定的，没有其他因素。 将研究的一些例子，特别是逻辑家族，从不同领域的兴趣模型，包括物理学，经济学和生态学。 该提案所解决的问题，当转换回这些模型时，与这些系统的长期行为和稳定性有关。 例如：人口会趋于长期均衡吗？ 该建议还涉及组合优化问题。 许多专家认为，如果坚持要求精确解，诸如“旅行推销员”问题之类的实际问题是难以解决的。 该提案将研究一种基于热力学思想的新方法，其目标是获得高性能的近似解。