Logic and C*-algebras

逻辑和 C* 代数

• 批准号: RGPIN-2017-05650
• 负责人: Farah, Ilijas
• 金额: $ 2.7万
• 依托单位: York University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=686958
• 关键词: Logic; algebras

This is an interdisciplinary proposal at the interface between C*-algebras and logic. A C*-algebra is an algebra of bounded linear operators on a complex Hilbert space closed under the formation of adjoints and the norm topology. Hilbert space is the infinite-dimensional modification of our standard three-dimensional space. The study of C*-algebras began in the 1940s, and has since expanded to touch much of modern mathematics, including number theory, geometry, ergodic theory, mathematical physics, and topology.***Two areas of mathematical logic with connections to C*-algebras are set theory and model theory. Some well-known and long-standing open problems about C*-algebras were recently resolved using set theory and model theory. Moreover, in some cases it was proved that these problems have an inherent foundational aspect and that the use of logic in their solution was necessary. ***Most important questions that I will work on are the existence of a K-theory reversing automorphism of the Calkin algebra and Naimark's problem. The first question was asked by Brown, Douglas and Fillmore in 1977. I have proved that a negative answer is relatively consistent with the standard axioms of set theory, ZFC and (together with Phillips and Weaver) that a closely related problem of the existence of outer automorphisms of the Calkin algebra cannot be decided in ZFC. Naimark's problem asks whether every C*-algebra with a unique (up to conjugacy) irreducible representation is isomorphic to the algebra of compact operators on some Hilbert space. A negative answer to this problem was shown to be relatively consistent with the standard axioms of set theory by C. Akemann and N. Weaver in 2002. I conjecture that the positive answer to Naimark's problem is also relatively consistent with the standard axioms of set theory. A confirmation of this conjecture would be a first step in extending Glimm's dichotomy to the realm of nonseparable C*-algebras.***Model theory studies the definable sets in mathematical structures and their first-order properties. The methods of continuous model theory were adapted to operator algebras less than a decade ago and much progress was made in understanding structure theory of massive algebras, such as ultrapowers and relative commutants. The latter algebras are more important and less understood, and I propose to investigate the exact formal properties which make them such an important tool in the study of operator algebras. ***A resolution of, or even a substantial progress on, any of these problems would provide new insight into the structure of C*-algebras. Mathematical logic (and set theory in particular) was developed in the `commutative' context and noncommutative problems pose new challenges. Further progress in applications of logic to operator algebras will require refinement of the existing techniques and development of new ones.

这是一个跨学科的建议在C*-代数和逻辑之间的接口。一个C*-代数是复希尔伯特空间上的有界线性算子的代数，它们在伴随和范数拓扑的形成下是闭的。希尔伯特空间是我们标准三维空间的无限维修改。C*-代数的研究始于20世纪40年代，此后扩展到现代数学的大部分领域，包括数论、几何、遍历理论、数学物理和拓扑学。*与C*-代数有关的两个数理逻辑领域是集合论和模型论。近年来，关于C*-代数的一些著名的和长期存在的未解决的问题被用集合论和模型论解决了。此外，在某些情况下，事实证明，这些问题有一个内在的基础方面，在解决这些问题时使用逻辑是必要的。* 最重要的问题，我将工作是存在一个K理论扭转自同构的卡尔金代数和奈马克的问题。第一个问题是布朗、道格拉斯和菲尔莫尔在1977年提出的。我已经证明，一个否定的答案是相对一致的标准公理集理论，ZFC和（连同菲利普斯和韦弗），一个密切相关的问题的存在外自同构的卡尔金代数不能决定在ZFC。奈马克问题是问是否每个具有唯一（直到共轭）不可约表示的C*-代数都同构于某个希尔伯特空间上的紧算子代数。这个问题的一个否定的答案被证明与集合论的标准公理是相对一致的。Akemann和N. 2002年的韦弗。我猜想，奈马克问题的肯定答案也与集合论的标准公理相对一致。这个猜想的证实将是将Glimm二分法扩展到不可分C*-代数领域的第一步。模型论研究数学结构中的可定义集合及其一阶性质。连续模型理论的方法在不到十年前被应用于算子代数，在理解大量代数的结构理论方面取得了很大进展，如超幂和相对交换子。后者代数更重要，更少的理解，我建议调查的确切形式的属性，使他们这样一个重要的工具，在研究算子代数。* 任何这些问题的解决，甚至是实质性的进展，都将为C*-代数的结构提供新的见解。数理逻辑（特别是集合论）是在“交换”的背景下发展起来的，非交换问题提出了新的挑战。进一步的进展，在应用逻辑算子代数将需要完善现有的技术和发展新的。