D. Croydon, Tsuyoshi Kato, M. Sasada, S. Tsujimoto
The box-ball system (BBS), introduced by Takahashi and Satsuma in 1990, is a cellular automaton that exhibits solitonic behaviour. In this article, we study the BBS when started from a random two-sided infinite particle configuration. For such a model, Ferrari et al. recently showed the invariance in distribution of Bernoulli product measures with density strictly less than 1 2 frac {1}{2} , and gave a soliton decomposition for invariant measures more generally. We study the BBS dynamics using the transformation of a nearest neighbour path encoding of the particle configuration given by ‘reflection in the past maximum’, which was famously shown by Pitman to connect Brownian motion and a three-dimensional Bessel process. We use this to characterise the set of configurations for which the dynamics are well-defined and reversible (i.e. can be inverted) for all times. The techniques developed to understand the deterministic dynamics are subsequently applied to study the evolution of the BBS from a random initial configuration. Specifically, we give simple sufficient conditions for random initial conditions to be invariant in distribution under the BBS dynamics, which we check in several natural examples, and also investigate the ergodicity of the relevant transformation. Furthermore, we analyse various probabilistic properties of the BBS that are commonly studied for interacting particle systems, such as the asymptotic behavior of the integrated current of particles and of a tagged particle. Finally, for Bernoulli product measures with parameter p ↑ 1 2 puparrow frac 12 (which may be considered the ‘high density’ regime), the path encoding we consider has a natural scaling limit, which motivates the introduction of a new continuous version of the BBS that we believe will be of independent interest as a dynamical system.
盒式球系统(BBS)由Takahashi和Satsuma于1990年提出,是一种具有孤子行为的元胞自动机。在本文中,我们从一个随机的双面无限粒子结构开始研究BBS。对于这样的模型,Ferrari等人最近证明了密度严格小于12 frac{1}{2}的伯努利积测度分布的不变量,并给出了更一般的不变量测度的孤子分解。我们使用由“过去极大值反射”给出的粒子构型的最近邻路径编码的变换来研究BBS动力学,这是Pitman著名的将布朗运动和三维贝塞尔过程联系起来的方法。我们用它来描述一组配置,其中动力学在任何时候都是定义良好的和可逆的(即可以反转)。为理解确定性动力学而开发的技术随后被应用于研究BBS从随机初始配置的演变。具体地说,我们给出了在BBS动力学下随机初始条件在分布上不变的简单充分条件,并在几个自然例子中进行了验证,同时研究了相关变换的遍历性。此外,我们还分析了通常用于相互作用粒子系统的BBS的各种概率性质,例如粒子和标记粒子的积分电流的渐近行为。最后,对于参数p ^ 1 ^ 2 p uprow frac 12的伯努利积测度(可以被认为是“高密度”状态),我们考虑的路径编码有一个自然的尺度限制,这促使我们引入新的连续版本的BBS,我们相信它将作为一个动态系统具有独立的兴趣。
{"title":"Dynamics of the Box-Ball System with Random Initial Conditions via Pitman’s Transformation","authors":"D. Croydon, Tsuyoshi Kato, M. Sasada, S. Tsujimoto","doi":"10.1090/memo/1398","DOIUrl":"https://doi.org/10.1090/memo/1398","url":null,"abstract":"The box-ball system (BBS), introduced by Takahashi and Satsuma in 1990, is a cellular automaton that exhibits solitonic behaviour. In this article, we study the BBS when started from a random two-sided infinite particle configuration. For such a model, Ferrari et al. recently showed the invariance in distribution of Bernoulli product measures with density strictly less than \u0000\u0000 \u0000 \u0000 1\u0000 2\u0000 \u0000 frac {1}{2}\u0000 \u0000\u0000, and gave a soliton decomposition for invariant measures more generally. We study the BBS dynamics using the transformation of a nearest neighbour path encoding of the particle configuration given by ‘reflection in the past maximum’, which was famously shown by Pitman to connect Brownian motion and a three-dimensional Bessel process. We use this to characterise the set of configurations for which the dynamics are well-defined and reversible (i.e. can be inverted) for all times. The techniques developed to understand the deterministic dynamics are subsequently applied to study the evolution of the BBS from a random initial configuration. Specifically, we give simple sufficient conditions for random initial conditions to be invariant in distribution under the BBS dynamics, which we check in several natural examples, and also investigate the ergodicity of the relevant transformation. Furthermore, we analyse various probabilistic properties of the BBS that are commonly studied for interacting particle systems, such as the asymptotic behavior of the integrated current of particles and of a tagged particle. Finally, for Bernoulli product measures with parameter \u0000\u0000 \u0000 \u0000 p\u0000 ↑\u0000 \u0000 1\u0000 2\u0000 \u0000 \u0000 puparrow frac 12\u0000 \u0000\u0000 (which may be considered the ‘high density’ regime), the path encoding we consider has a natural scaling limit, which motivates the introduction of a new continuous version of the BBS that we believe will be of independent interest as a dynamical system.","PeriodicalId":49828,"journal":{"name":"Memoirs of the American Mathematical Society","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2018-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47334698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We study lower bounds on multilinear operators with Gaussian kernels acting on Lebesgue spaces, with exponents below one. We put forward natural conditions when the optimal constant can be computed by inspecting centered Gaussian functions only, and we give necessary and sufficient conditions for this constant to be positive. Our work provides a counterpart to Lieb’s results on maximizers of multilinear operators with real Gaussian kernels, also known as the multidimensional Brascamp-Lieb inequality. It unifies and extends several inverse inequalities.
{"title":"Positive Gaussian Kernels also Have Gaussian Minimizers","authors":"F. Barthe, P. Wolff","doi":"10.1090/memo/1359","DOIUrl":"https://doi.org/10.1090/memo/1359","url":null,"abstract":"We study lower bounds on multilinear operators with Gaussian kernels acting on Lebesgue spaces, with exponents below one. We put forward natural conditions when the optimal constant can be computed by inspecting centered Gaussian functions only, and we give necessary and sufficient conditions for this constant to be positive. Our work provides a counterpart to Lieb’s results on maximizers of multilinear operators with real Gaussian kernels, also known as the multidimensional Brascamp-Lieb inequality. It unifies and extends several inverse inequalities.","PeriodicalId":49828,"journal":{"name":"Memoirs of the American Mathematical Society","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2018-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45931619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction • Acknowledgements • Preliminaries • Some general results • The cases $c_1=4$ and $c_1 = 5$ on ${mathbb P}^2$ • The case $c_1 = 4$, $c_2 = 5, 6$ on ${mathbb P}^3$ • The case $c_1 = 4$, $c_2 = 7$ on ${mathbb P}^3$ • The case $c_1 = 4$, $c_2 = 8$ on ${mathbb P}^3$ • The case $c_1 = 4$, $5 leq c_2 leq 8$ on ${mathbb P}^n$, $n geq 4$ • Appendix A. The case $c_1 = 4$, $c_2 = 8$, $c_3 = 2$ on ${mathbb P}^3$ • Appendix B. The case $c_1 = 4$, $c_2 = 8$, $c_3 = 4$ on ${mathbb P}^3$ • Bibliography •
{"title":"Globally Generated Vector Bundles with Small _{tiny}1 on Projective Spaces","authors":"C. Anghel, I. Coandă, N. Manolache","doi":"10.1090/memo/1209","DOIUrl":"https://doi.org/10.1090/memo/1209","url":null,"abstract":"Introduction • Acknowledgements • Preliminaries • Some general results • The cases $c_1=4$ and $c_1 = 5$ on ${mathbb P}^2$ • The case $c_1 = 4$, $c_2 = 5, 6$ on ${mathbb P}^3$ • The case $c_1 = 4$, $c_2 = 7$ on ${mathbb P}^3$ • The case $c_1 = 4$, $c_2 = 8$ on ${mathbb P}^3$ • The case $c_1 = 4$, $5 leq c_2 leq 8$ on ${mathbb P}^n$, $n geq 4$ • Appendix A. The case $c_1 = 4$, $c_2 = 8$, $c_3 = 2$ on ${mathbb P}^3$ • Appendix B. The case $c_1 = 4$, $c_2 = 8$, $c_3 = 4$ on ${mathbb P}^3$ • Bibliography •","PeriodicalId":49828,"journal":{"name":"Memoirs of the American Mathematical Society","volume":"253 1","pages":"0-0"},"PeriodicalIF":1.9,"publicationDate":"2018-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43046158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Two themes drive this article: identifying the structure necessary to formulate quaternionic operator theory and revealing the relation between complex and quaternionic operator theory. The theory of quaternionic right linear operators is usually formulated assuming the existenc of both a right- and a left-multiplication on the Banach space $V$, as the space of bounded operators on $V$ is otherwise not a quaternionic linear space. A right linear operator is however only associated with the right-multiplication and in certain settings, e.g. on Hilbert spaces, the left-multiplication is not defined a priori but must be chosen randomly. Spectral properties of an operator should hence be independent of this left multiplication. We show that results derived from functional calculi for intrinsic slice functions can be formulated without the assumption of a left multiplication. We develop the S-functional calculus in this setting and a new approach to spectral integration. This approach has a clear interpretation in terms of the right linear structure on the space and allows to formulate the spectral theorem without using any randomly chosen structure. Our techniques only apply to intrinsic slice functions, but only these functions are compatible with the basic intuition of a functional calculus that $f(T)$ should be defined by letting $f$ act on the spectral values of $T$. Using these tools, we develop a theory of quaternionic spectral operators. In particular, we show the existence of a canonical decomposition of such operator and discuss its behavior under the S-functional calculus. Finally, we show a relation with complex operator theory: if we embed the complex numbers into the quaternions, then complex and quaternionic operator theory are consistent. The symmetry of intrinsic slice functions guarantees that this compatibility is true for any imbedding of the complex numbers.
{"title":"Operator Theory on One-Sided Quaternionic\u0000 Linear Spaces: Intrinsic S-Functional Calculus and\u0000 Spectral Operators","authors":"J. Gantner","doi":"10.1090/memo/1297","DOIUrl":"https://doi.org/10.1090/memo/1297","url":null,"abstract":"Two themes drive this article: identifying the structure necessary to formulate quaternionic operator theory and revealing the relation between complex and quaternionic operator theory. \u0000The theory of quaternionic right linear operators is usually formulated assuming the existenc of both a right- and a left-multiplication on the Banach space $V$, as the space of bounded operators on $V$ is otherwise not a quaternionic linear space. A right linear operator is however only associated with the right-multiplication and in certain settings, e.g. on Hilbert spaces, the left-multiplication is not defined a priori but must be chosen randomly. Spectral properties of an operator should hence be independent of this left multiplication. \u0000We show that results derived from functional calculi for intrinsic slice functions can be formulated without the assumption of a left multiplication. We develop the S-functional calculus in this setting and a new approach to spectral integration. This approach has a clear interpretation in terms of the right linear structure on the space and allows to formulate the spectral theorem without using any randomly chosen structure. Our techniques only apply to intrinsic slice functions, but only these functions are compatible with the basic intuition of a functional calculus that $f(T)$ should be defined by letting $f$ act on the spectral values of $T$. \u0000Using these tools, we develop a theory of quaternionic spectral operators. In particular, we show the existence of a canonical decomposition of such operator and discuss its behavior under the S-functional calculus. \u0000Finally, we show a relation with complex operator theory: if we embed the complex numbers into the quaternions, then complex and quaternionic operator theory are consistent. The symmetry of intrinsic slice functions guarantees that this compatibility is true for any imbedding of the complex numbers.","PeriodicalId":49828,"journal":{"name":"Memoirs of the American Mathematical Society","volume":"26 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2018-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82632674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}