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Variational construction of singular characteristics and propagation of singularities 奇异特征的变量构造和奇异点的传播
Pub Date : 2024-09-02 DOI: arxiv-2409.00961
Piermarco Cannarsa, Wei Cheng, Jiahui Hong, Kaizhi Wang
On a smooth closed manifold $M$, we introduce a novel theory of maximal slopecurves for any pair $(phi,H)$ with $phi$ a semiconcave function and $H$ aHamiltonian. By using the notion of maximal slope curve from gradient flow theory, theintrinsic singular characteristics constructed in [Cannarsa, P.; Cheng, W.,textit{Generalized characteristics and Lax-Oleinik operators: global theory}.Calc. Var. Partial Differential Equations 56 (2017), no. 5, 56:12], the smoothapproximation method developed in [Cannarsa, P.; Yu, Y. textit{Singulardynamics for semiconcave functions}. J. Eur. Math. Soc. 11 (2009), no. 5,999--1024], and the broken characteristics studied in [Khanin, K.; Sobolevski,A., textit{On dynamics of Lagrangian trajectories for Hamilton-Jacobiequations}. Arch. Ration. Mech. Anal. 219 (2016), no. 2, 861--885], we provethe existence and stability of such maximal slope curves and discuss certainnew weak KAM features. We also prove that maximal slope curves for any pair$(phi,H)$ are exactly broken characteristics which have right derivativeseverywhere. Applying this theory, we establish a global variational construction ofstrict singular characteristics and broken characteristics. Moreover, we provea result on the global propagation of cut points along generalizedcharacteristics, as well as a result on the propagation of singular pointsalong strict singular characteristics, for weak KAM solutions. We also obtainthe continuity equation along strict singular characteristics which clarifiesthe mass transport nature in the problem of propagation of singularities.
在光滑闭合流形 $M$ 上,我们为任意一对 $(phi,H)$(其中 $phi$ 为半凹函数,$H$ 为哈密尔顿函数)引入了一种新的最大斜曲线理论。通过使用梯度流理论中的最大斜率曲线概念,[Cannarsa, P.; Cheng, W., textit{Generalized characteristics and Lax-Oleinik operators: global theory}.Calc. Var.Var.Partial Differential Equations 56 (2017), no.5, 56:12], the smoothapproximation method developed in [Cannarsa, P.; Yu, Y. textit{Singulardynamics for semiconcave functions}.J. Eur.11 (2009), no.11 (2009), no.5,999--1024], and the broken characteristics studied in [Khanin, K.; Sobolevski,A., textit{On dynamics of Lagrangian trajectories for Hamilton-Jacobiequations}. Arch.Arch.Ration.Mech.Anal.219 (2016), no. 2, 861--885], we provethe existence and stability of such maximal slope curves and discuss certainnew weak KAM features.我们还证明了任何一对$(phi,H)$的最大斜率曲线都是精确破碎的特征,其右导数无处不在。应用这一理论,我们建立了严格奇异特征和破碎特征的全局变分构造。此外,我们还证明了弱 KAM 解的切点沿广义特征全局传播的结果,以及奇异点沿严格奇异特征传播的结果。我们还得到了沿严格奇异特征的连续性方程,从而澄清了奇异点传播问题中的质量传输性质。
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引用次数: 0
Finding Large Independent Sets in Networks Using Competitive Dynamics 利用竞争动力学寻找网络中的大型独立集
Pub Date : 2024-09-02 DOI: arxiv-2409.01336
Niek Mooij, Ivan Kryven
Many decision-making algorithms draw inspiration from the inner workings ofindividual biological systems. However, it remains unclear whether collectivebehavior among biological species can also lead to solutions for computationaltasks. By studying the coexistence of species that interact through simplerules on a network, we demonstrate that the underlying dynamical system canrecover near-optimal solutions to the maximum independent set problem -- afundamental, computationally hard problem in graph theory. Furthermore, weobserve that the optimality of these solutions is improved when the competitivepressure in the system is gradually increased. We explain this phenomenon byshowing that the cascade of bifurcation points, which occurs with risingcompetitive pressure in our dynamical system, naturally gives rise to Katzcentrality-based node removal in the network. By formalizing this connection,we propose a biologically inspired discrete algorithm for approximating themaximum independent set problem on a graph. Our results indicate that complexsystems may collectively possess the capacity to perform non-trivialcomputations, with implications spanning biology, economics, and other fields.
许多决策算法都是从单个生物系统的内部运作中汲取灵感的。然而,生物物种之间的集体行为是否也能为计算任务带来解决方案,目前仍不清楚。通过研究物种在网络上通过简约相互作用的共存情况,我们证明了底层动力系统可以恢复最大独立集问题的近似最优解--该问题是图论中一个基本的、难以计算的问题。此外,我们还发现,当系统中的竞争压力逐渐增大时,这些解的最优性会得到改善。我们对这一现象的解释是,我们的动态系统中随着竞争压力的上升而出现的级联分岔点,自然会引起网络中基于卡茨中心性的节点移除。通过形式化这种联系,我们提出了一种受生物学启发的离散算法,用于近似图上的最大独立集问题。我们的研究结果表明,复杂系统可能共同拥有进行非三维计算的能力,其影响横跨生物学、经济学和其他领域。
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引用次数: 0
Four closed characteristics on compact star-shaped hypersurfaces in $mathbb{R}^{8}$ $mathbb{R}^{8}$中紧凑星形超曲面上的四个封闭特征
Pub Date : 2024-09-02 DOI: arxiv-2409.04460
Huagui Duan, Dong Xie
In this paper, we proved that for every non-degenerate $C^3$ compactstar-shaped hypersurface $Sigma$ in $mathbb{R}^{8}$ which carries no primeclosed characteristic of Maslov-type index $-1$, there exist at least fourprime closed characteristics on $Sigma$.
在本文中,我们证明了对于$mathbb{R}^{8}$中的每一个非退化的$C^3$紧凑星形超曲面$Sigma$,它不带马斯洛夫型索引$-1$的初等封闭特征,在$Sigma$上存在至少四个初等封闭特征。
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引用次数: 0
Distributions of periodic points for the Dyck shift and the heterochaos baker maps 戴克平移和异相贝克图的周期点分布
Pub Date : 2024-09-02 DOI: arxiv-2409.01261
Hiroki Takahasi
The heterochaos baker maps are piecewise affine maps on the square or thecube that are one of the simplest partially hyperbolic systems. The Dyck shiftis a well-known example of a subshift that has two fully supported ergodicmeasures of maximal entropy (MMEs). We show that the two ergodic MMEs of theDyck shift are represented as asymptotic distributions of sets of periodicpoints of different multipliers. We transfer this result to the heterochaosbaker maps, and show that their two ergodic MMEs are represented as asymptoticdistributions of sets of periodic points of different unstable dimensions.
异相贝克映射是正方形或立方体上的片断仿射映射,是最简单的部分双曲系统之一。戴克平移是一个著名的子平移例子,它有两个完全支持的最大熵的遍历度量(MMEs)。我们证明,戴克平移的两个遍历最大熵(MME)表现为不同乘数的周期点集合的渐近分布。我们将这一结果转移到异相贝克映射,并证明它们的两个遍历最大熵(MME)表示为不同不稳定维数的周期点集的渐近分布。
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引用次数: 0
A geometric approach to Mather quotient problem 解决马瑟商数问题的几何方法
Pub Date : 2024-09-02 DOI: arxiv-2409.00958
Wei Cheng, Wenxue Wei
Let $(M,g)$ be a closed, connected and orientable Riemannian manifold withnonnegative Ricci curvature. Consider a Lagrangian $L(x,v):TMtoR$ defined by$L(x,v):=frac 12g_x(v,v)-omega(v)+c$, where $cinR$ and $omega$ is a closed1-form. From the perspective of differential geometry, we estimate theLaplacian of the weak KAM solution $u$ to the associated Hamilton-Jacobiequation $H(x,du)=c[L]$ in the barrier sense. This analysis enables us to provethat each weak KAM solution $u$ is constant if and only if $omega$ is aharmonic 1-form. Furthermore, we explore several applications to the Matherquotient and Ma~n'e's Lagrangian.
让$(M,g)$ 是一个封闭的、连通的、可定向的黎曼流形,具有负黎奇曲率。考虑由$L(x,v):=frac 12g_x(v,v)-omega(v)+c$ 定义的拉格朗日$L(x,v):TMtoR$ ,其中$cinR$ 和$omega$ 是一个封闭的1-形式。从微分几何的角度,我们估算了相关汉密尔顿-雅各比方程 $H(x,du)=c[L]$ 的弱 KAM 解 $u$ 在壁垒意义上的拉普拉斯。这一分析使我们能够证明,当且仅当 $omega$ 是谐 1 形时,每个弱 KAM 解 $u$ 都是常数。此外,我们还探讨了马瑟商数和马氏拉格朗日的一些应用。
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引用次数: 0
Conformal measures of (anti)holomorphic correspondences 反)全态对应的共形测量
Pub Date : 2024-09-02 DOI: arxiv-2409.01361
Nils Hemmingsson, Xiaoran Li, Zhiqiang Li
In this paper, we study the existence and properties of conformal measures onlimit sets of (anti)holomorphic correspondences. We show that if the criticalexponent satisfies $1leq delta_{operatorname{crit}}(x) <+infty,$ thecorrespondence $F$ is (relatively) hyperbolic on the limit set $Lambda_+(x)$,and $Lambda_+(x)$ is minimal, then $Lambda_+(x)$ admits a non-atomicconformal measure for $F$ and the Hausdorff dimension of $Lambda_+(x)$ isstrictly less than 2. As a special case, this shows that for a parameter $a$ inthe interior of a hyperbolic component of the modular Mandelbrot set, the limitset of the Bullett--Penrose correspondence $F_a$ has a non-atomic conformalmeasure and its Hausdorff dimension is strictly less than 2. The same resultshold for the LLMM correspondences, under some extra assumptions on its definingfunction $f$.
在本文中,我们研究了(反)全态对应的极限集上保角量度的存在性和性质。我们证明,如果临界分量满足$1leq delta_operatorname{crit}}(x) <+infty, $F$在极限集$Lambda_+(x)$上是(相对)双曲的、并且 $Lambda_+(x)$ 是最小的,那么 $Lambda_+(x)$ 允许 $F$ 的非原子共形度量,并且 $Lambda_+(x)$ 的 Hausdorff 维度严格小于 2。作为特例,这表明对于模态曼德尔布罗特集双曲分量内部的参数 $a$,Bullett--Penrose 对应的极限集 $F_a$ 具有非原子共形度量,且其 Hausdorff 维度严格小于 2。在其定义函数 $f$ 的一些额外假设下,LLMM 对应也有同样的结果。
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引用次数: 0
Rapidly yawing spheroids in viscous shear flow: Emergent loss of symmetry 粘性剪切流中快速偏航的球体:新出现的对称性丧失
Pub Date : 2024-09-02 DOI: arxiv-2409.01273
Mohit P. Dalwadi
We investigate the emergent dynamics of a rapidly yawing spheroidal swimmerinteracting with a viscous shear flow. We show that the rapid yawing generatesnon-axisymmetric emergent effects, with the active swimmer behaving as aneffective passive particle with two orthogonal planes of symmetry. The shape ofthe equivalent effective particle is different to the average shape of theactive particle. Moreover, despite having two planes of symmetry, theequivalent passive particle is not an ellipsoid in general, except for specificscenarios in which the effective shape is a spheroid. We use a multiple scalesanalysis for systems to derive the emergent swimmer behaviour, which requiressolving a nonautonomous nonlinear 3D dynamical system, and we validate ouranalysis via comparison to numerical simulations.
我们研究了快速偏航的球形游泳者与粘性剪切流相互作用的突发动力学。我们发现,快速偏航产生了非轴对称的突现效应,主动游动体表现为具有两个正交对称平面的有效被动粒子。等效有效粒子的形状与主动粒子的平均形状不同。此外,尽管有两个对称平面,但等效被动粒子一般不是椭圆体,只有在特定情况下,有效形状才是球体。我们使用多尺度系统分析来推导出现的游泳者行为,这需要解决一个非自主的非线性三维动力学系统,我们通过与数值模拟的比较来验证我们的分析。
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引用次数: 0
Latent Space Dynamics Learning for Stiff Collisional-radiative Models 刚性碰撞辐射模型的潜空间动力学学习
Pub Date : 2024-09-01 DOI: arxiv-2409.05893
Xuping Xie, Qi Tang, Xianzhu Tang
Collisional-radiative (CR) models describe the atomic processes in a plasmaby tracking the population density in the ground and excited states for eachcharge state of the atom or ion. These models predict important plasmaproperties such as charge state distributions and radiative emissivity andopacity. Accurate CR modeling is essential in radiative plasma modeling formagnetic fusion, especially when significant amount of impurities areintroduced into the plasmas. In radiative plasma simulations, a CR model, whichis a set of high-dimensional stiff ordinary differential equations (ODE), needsto be solved on each grid point in the configuration space, which can overwhelmthe plasma simulation cost. In this work, we propose a deep learning methodthat discovers the latent space and learns its corresponding latent dynamics,which can capture the essential physics to make accurate predictions at muchlower online computational cost. To facilitate coupling of the latent space CRdynamics with the plasma simulation model in physical variables, our latentspace in the autoencoder must be a grey box, consisting of a physical latentspace and a data-driven or blackbox latent space. It has been demonstrated thatthe proposed architecture can accurately predict both the full-order CRdynamics and the critical physical quantity of interest, the so-calledradiative power loss rate.
碰撞辐射(CR)模型描述了等离子体中的原子过程,跟踪原子或离子的每种电荷态在基态和激发态的种群密度。这些模型可以预测重要的等离子体特性,如电荷状态分布、辐射发射率和辐照度。精确的 CR 建模对于磁核聚变辐射等离子体建模至关重要,尤其是当等离子体中引入大量杂质时。在辐射等离子体模拟中,CR 模型是一组高维僵化常微分方程(ODE),需要在配置空间的每个网格点上求解,这会导致等离子体模拟成本过高。在这项工作中,我们提出了一种深度学习方法,它能发现潜在空间并学习其相应的潜在动力学,从而捕捉到重要的物理现象,以更低的在线计算成本进行精确预测。为了方便潜空间 CR 动力学与等离子体仿真模型在物理变量上的耦合,我们在自动编码器中的潜空间必须是一个灰盒,由物理潜空间和数据驱动或黑盒潜空间组成。实验证明,所提出的架构可以准确预测全阶 CR 动力学和所关注的关键物理量,即所谓的辐射功率损耗率。
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引用次数: 0
Polynomial shape adic systems are inherently expansive 多项式形状自适应系统本身具有扩展性
Pub Date : 2024-09-01 DOI: arxiv-2409.00762
Sarah Frick, Karl Petersen, Sandi Shields
To study any dynamical system it is useful to find a partition that allowsessentially faithful encoding (injective, up to a small exceptional set) into asubshift. Most topological and measure-theoretic systems can be represented byBratteli-Vershik (or adic, or BV) systems. So it is natural to ask when can aBV system be encoded essentially faithfully. We show here that for BV diagramsdefined by homogeneous positive integer multivariable polynomials, and a widefamily of their generalizations, which we call polynomial shape diagrams, forevery choice of the edge ordering the coding according to initial path segmentsof a fixed finite length is injective off of a negligible exceptional set.
要研究任何动力系统,都需要找到一个分区,允许将本质上忠实的编码(注入式,直到一个小的例外集)转换成子移位。大多数拓扑和度量理论系统都可以用布拉泰里-韦希克(或阿迪克,或 BV)系统来表示。因此,我们自然会问,BV 系统什么时候可以基本忠实地编码?我们在这里证明,对于由同质正整数多变量多项式定义的 BV 图,以及它们的广义家族(我们称之为多项式形状图),根据固定有限长度的初始路径段进行编码的边排序的永久选择是可忽略的例外集的注入式。
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引用次数: 0
Data Assimilation to the Primitive Equations in $H^2$ 对 $H^2$ 原始方程的数据同化
Pub Date : 2024-09-01 DOI: arxiv-2409.00579
Ken Furukawa
In this paper we prove that the solution to the primitive equations ispredicted by the corresponding data assimilation(DA) equations in $H^2$.Although, the DA equation does not include the direct information about thebase solution and its initial conditions, the solution to the DA equationexponentially convergence to the base(original) solution when the externalforces are known even before they are observed. Additionally, when the externalforce is not completely known but its spatially dense observations areavailable, then the DA is stable, $i.e.$ the DA solution lies in a sufficientlysmall neighborhood of the base solution.
本文证明,原始方程的解是由$H^2$中相应的数据同化(DA)方程预测的。虽然,DA方程不包括基解及其初始条件的直接信息,但当外力在观测之前就已知时,DA方程的解会指数收敛到基解(原始解)。此外,当外力不完全已知,但其空间密度观测值可用时,DA是稳定的,即DA解位于基解的一个足够小的邻域内。
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引用次数: 0
期刊
arXiv - MATH - Dynamical Systems
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