A_4型量子群中紧单项式的区域

整体晶体基(又称为典范基)在量子群及其表示理论中起着重要的作用. 紧单项式是典范基中最简单的元素.本文基于Lusztig的工作来确定A_4型量子群中紧单项式的区域.     

Yamabe流下黎曼流形上热方程的梯度估计

研究了在Yamabe流下演化的一个完备非紧黎曼流形,对流形上热方程的正解给出了两种局部的梯度估计.作为应用,可以得到这个热方程的Harnack不等式.     

随机非局部扩散方程的随机吸引子的存在性

证明了带加性噪声的非局部扩散方程的随机吸引子的存在性和唯一性.为了克服无界区域Sobolev嵌入不紧的问题,该文运用尾估计和分解相结合的方法证明方程解的渐近紧性.     

局部熵的拓扑压重分形谱

本文考察不变测度的局部熵的重分形分析.给出了集合的非紧拓扑压和非紧(q,μ)-压的定义,并建立了二者之间的联系.利用非紧集或非不变集的(q,μ)-压,给出了局部熵的拓扑压重分形谱的一个等式.此结论推广了文献[Halsey,T.et al.,Phys.Rev.A,1986,33(2):1141-1151]的部分结果.     

LF积空间与诱导空间的局部良紧性

本文在［１］的基础上，讨论了乘积ＬＦ拓扑空间与其因子空间、诱导空间与其底空间的局部良紧性之间的关系，证明了Ｋ—型局部良紧性是Ｌ—好的推广。（Ｋ＝１，３，５）。对于诱导空间，证明了局部良紧性可以加强分离性，给出了局部良紧子空间表示定理。     

连通和序列紧的Rectifiable空间（英文）

本文主要讨论了rectifiable空间的连通,序列紧和κ-Frechet-Urysohn性质.证明了以下结果:(1)若G是局部σ-序列紧且具有Souslin性质的rectifiable空间,则G是σ-序列紧的.(2)每一连通的局部σ-紧的rectifiable空间G是σ-紧的.(3)若rectifiable空间G的每一紧(可数紧,序列紧)的子空间是Frechet-Urysohn,则G的每一紧(可数紧,序列紧)的子空间是强Frechet-Urysohn.这些结果推广了拓扑群中的相应结果.     

非紧的一般化凸空间上不动点定理和supinfsup不等式

利用一般化凸空间上的KKM型定理得到有限交定理,然后作为应用讨论了在没有紧性限制的一般化凸空间上集值映射的不动点的存在问题以及Von Neumann-Fan型supinfsup不等式(等式)问题,最后给出了极大极小等式.     

拓扑群中广义度量性质的一个注记

主要讨论拓扑群中的一些广义度量性质.证明了对于拓扑群G和G的局部紧度量子群H,如果商群G/H是层空间(半层空间,κ半层空间,σ空间),则G也是层空间(半层空间, κ半层空间,σ空间),这肯定回答了Arhangel'skii A.V.和Uspenskij V.V.提出的一个问题.同时还讨论了弱拟第一可数的,不含Sω的闭拷贝的仿拓扑群.     

Lie理论中一类Poisson结构的构造

Poisson几何是Hamilton力学及辛流形紧化自然的研究框架.本文介绍了一类与Lie理论有关的Poisson流形.这类Poisson流形的构造来自于量子群,并与分次扩张Poisson代数有着紧密的联系.     

关于双参数量子群的注记(I)

借助于Euler型, 给出了一类(对应于半单Lie代数的)双参数量子群的更为简便的定义方式, 证明了所定义量子群的正部分在双参数满足适当条件下是互为2-上圈形变的, 并给出了该正部分 在Kashiwara意义下的斜微分算子实现.     

Block maps and Fourier analysis

We introduce block maps for subfactors and study their dynamic systems. We prove that the limit points of the dynamic system are positive multiples of biprojections and zero. For the Z_2 case, the asymptotic phenomenon of the block map coincides with that of the 2 D Ising model. The study of block maps requires a further development of our recent work on the Fourier analysis of subfactors. We generalize the notion of sum set estimates in additive combinatorics for subfactors and prove the exact inverse sum set theorem. Using this new method, we characterize the extremal pairs of Young's inequality for subfactors, as well as the extremal operators of the Hausdorff-Young inequality.     

Convolution semigroups of states

Convolution semigroups of states on a quantum group form the natural noncommutative analogue of convolution semigroups of probability measures on a locally compact group. Here we initiate a theory of weakly continuous convolution semigroups of functionals on a C*-bialgebra, the noncommutative counterpart of a locally compact semigroup. On locally compact quantum groups we obtain a bijective correspondence between such convolution semigroups and a class of C ₀-semigroups of maps which we characterise. On C*-bialgebras of discrete type we show that all weakly continuous convolution semigroups of states are automatically norm-continuous. As an application we deduce a known characterisation of continuous conditionally positive-definite Hermitian functions on a compact group.     

The emergence of time

Classically, one could imagine a completely static space, thus without time. As is known, this picture is unconceivable in quantum physics due to vacuum fluctuations. The fundamental difference between the two frameworks is that classical physics is commutative (simultaneous observables) while quantum physics is intrinsically noncommutative (Heisenberg uncertainty relations). In this sense, we may say that time is generated by noncommutativity; if this statement is correct, we should be able to derive time out of a noncommutative space. We know that a von Neumann algebra is a noncommutative space. About 50 years ago the Tomita–Takesaki modular theory revealed an intrinsic evolution associated with any given (faithful, normal) state of a von Neumann algebra, so a noncommutative space is intrinsically dynamical. This evolution is characterised by the Kubo–Martin–Schwinger thermal equilibrium condition in quantum statistical mechanics (Haag, Hugenholtz, Winnink), thus modular time is related to temperature. Indeed, positivity of temperature fixes a quantum-thermodynamical arrow of time. We shall sketch some aspects of our recent work extending the modular evolution to a quantum operation (completely positive map) level and how this gives a mathematically rigorous understanding of entropy bounds in physics and information theory. A key point is the relation with Jones’ index of subfactors. In the last part, we outline further recent entropy computations in relativistic quantum field theory models by operator algebraic methods, that can be read also within classical information theory. The information contained in a classical wave packet is defined by the modular theory of standard subspaces and related to the quantum null energy inequality.     

Spectral synthesis problems on locally compact groups

Spectral analysis and spectral synthesis problems are formulated on noncommutative locally compact groups and solved on compact groups.     

Extensions of locally compact quantum groups and the bicrossed product construction

In the framework of locally compact quantum groups, we study cocycle actions. We develop the cocycle bicrossed product construction, starting from a matched pair of locally compact quantum groups. We define exact sequences and establish a one-to-one correspondence between cocycle bicrossed products and cleft extensions. In this way, we obtain new examples of locally compact quantum groups.     

Uncertainty principles for locally compact quantum groups

In this paper, we prove the Donoho–Stark uncertainty principle for locally compact quantum groups and characterize the minimizer which are bi-shifts of group-like projections. We also prove the Hirschman–Beckner uncertainty principle for compact quantum groups and discrete quantum groups. Furthermore, we show Hardy's uncertainty principle for locally compact quantum groups in terms of bi-shifts of group-like projections.     

A simple definition for locally compact quantum groups

In this Note we propose a simple definition of a locally compact quantum group in reduced form. By the word “reduced” we mean that we suppose the Haar weight to be faithful, and hence we define in fact arbitrary locally compact quantum groups represented on the L²-space of the Haar weight. We construct the multiplicative unitary associated with our quantum group. We construct the antipode with its polar decomposition, and the modular element. We prove the unicity of the Haar weights, define the dual and prove a Pontryagin duality theorem.     

On the similarity problem for locally compact quantum groups

A well-known theorem of Day and Dixmier states that any uniformly bounded representation of an amenable locally compact group G on a Hilbert space is similar to a unitary representation. Within the category of locally compact quantum groups, the conjectural analogue of the Day–Dixmier theorem is that every completely bounded Hilbert space representation of the convolution algebra of an amenable locally compact quantum group should be similar to a ?-representation. We prove that this conjecture is false for a large class of non-Kac type compact quantum groups, including all q-deformations of compact simply connected semisimple Lie groups. On the other hand, within the Kac framework, we prove that the Day–Dixmier theorem does indeed hold for several new classes of examples, including amenable discrete quantum groups of Kac-type.     

On cocycle twisting of compact quantum groups

We provide a class of examples of compact quantum groups and unitary 2-cocycles on them, such that the twisted quantum groups are non-compact, but still locally compact quantum groups (in the sense of Kustermans and Vaes). This also gives examples of cocycle twists where the underlying C^∗-algebra of the quantum group changes.     

Measurable Kac cohomology for bicrossed products

We study the Kac cohomology for matched pairs of locally compact groups. This cohomology theory arises from the extension theory of locally compact quantum groups. We prove a measurable version of the Kac exact sequence and provide methods to compute the cohomology. We give explicit calculations in several examples using results of Moore and Wigner.