Noncommutative Algebraic Topology

Lead Research Organisation: CARDIFF UNIVERSITY
Department Name: Sch of Mathematics

Abstract

Algebraic Topology is the study of spaces using algebraic methods. By a basic duality principle, spaces correspond to commutative algebras. In Noncommutative Geometry, one studies noncommutative spaces that underlie noncommutative algebras. Such algebras show up naturally in a plethora of situations, for instance, when one consider symmetries or deformations of spaces.The study of noncommutative spaces is not only interesting in itself, but also has important applications to various other branches of mathematical and physical sciences. For instance, analysis of the topological K-theory of noncommutative spaces underlying discrete groups allows one to deduce results in pure algebra, topology and geometry. Moreover, in some case, the best results are accessible only through noncommutative geometric methods. In mathematical physics, noncommutative (operator) algebras arise as algebra of observes. In fact, this is how noncommutative geometry was initiated by von Neumann in the first place. Some current research in theoretical physics focus on investigating the space-time as a noncommutative space.My proposal concerns the study of noncommutative algebraic topology, more precisely, the extension of algebraic topological methods to noncommutative geometry. This involves rewriting homotopy theory for noncommutative spaces in terms of modern algebraic topological machinery and making systematic use of various standard techniques such as completion and localization. More concretely, my research proposal consists of four interconnected projects that focus on homotopical algebra, algebraic and connective K-theories for noncommutative spaces and Banach KK-theory, respectively.The research fellowship is to be held at Cardiff University, because it has a strong tradition of Noncommutative Geometry and Mathematical Physics. Also Cardiff University is the largest partner of Wales Institute of Mathematical and Computational Sciences and leader of its Mathematical Physics cluster, whose members include the prestigious string theory group at Swansea and quantum control group at Aberystwyth. In order both to promote successful research and discuss future directions with experts in the relevant fields, I plan to make scientific trips to Muenster University and University of Sheffield.

Planned Impact

As a research in pure mathematics, my research will mostly have academic impact. As can be seen from how number theory is used in modern cryptography or how Fourier analysis is used in signal processing, research in pure mathematics could have profound social and economic impact. However, such applications depend on developments in the future and cannot be predicted. Therefore I will concentrate on the academic impact of my research. My research will advance the field of noncommutative geometry by adding new results and, maybe more importantly, new techniques, enhancing the knowledge economy. By making systematic use of algebraic topological methods, I hope to introduce fresh ideas and new perspectives to old problems in noncommutative geometry. At the same time, this will enable me to offer new and interesting problems to algebraic topologists, that are based on examples coming from operator algebras. Furthermore, new developments in noncommutative geometry should result in developments in topology and geometry, extending already known connections. Hence my proposed research should enhance the synergy between algebraic topology and noncommutative geometry, contributing towards the health of the disciplines.

Publications

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Katsura T (2014) On the invariant uniform Roe algebra in Journal of Operator Theory

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SHULMAN T (2019) APPROXIMATIONS OF SUBHOMOGENEOUS ALGEBRAS in Bulletin of the Australian Mathematical Society

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Uuye O (2016) $K$-Continuity Is Equivalent To $K$-Exactness in MATHEMATICA SCANDINAVICA

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Uuye O (2011) Multiplicativity of the JLO-character in Journal of Noncommutative Geometry

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Uuye O (2011) Restriction maps in equivariant KK -theory in Journal of K-Theory

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Uuye O (2014) Unsuspended connective $E$-theory English in Journal of Operator Theory

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Uuye O (2020) The Fubini Product and Its Applications in Bulletin of the Malaysian Mathematical Sciences Society

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Uuye O (2020) Correction to: The Fubini Product and Its Applications in Bulletin of the Malaysian Mathematical Sciences Society

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Uuye O (2013) Homotopical algebra for C*-algebras in Journal of Noncommutative Geometry

 
Description There is a fundamental duality between spaces and commutative algebras. Noncommutative topology extends this duality to noncommutative spaces and noncommutative algebras.
I studied algebraic topology of noncommutative spaces in my project.

K-theory is a basic tool in the study of noncommutative spaces. I developed a bivariant version of K-theory that is unsuspended and connective for noncommutative spaces. This is a matricial enrichment of noncommutative shape theory. As an application I extended and provided new proof of results of Dadarlat-Loring and T. Shulman.

I also studied extension and continuity properties of noncommutative spaces and noncommutative dynamical systems. I proved that a noncommutative dynamical system is (K)-exact if and only if it is (K)-continuous with respect to the minimal tensor product. A major ingredient in the proof is a simplification of a result of Dadarlat.

With T. Katsura, we studied the invariant translation approximation property of groups. An important object in the study of index theory of noncompact manifolds is the uniform Roe algebra of the space. We studied the invariant part of the uniform Roe algebra of a countable discrete group and showed that a group has the approximation property if and only if it is exact and has the strong invariant translation approximation property. This answers a question by J. Zacharias. It opened up important new questions which we are currently studying.
Exploitation Route My results can be used by mathematicians to further study noncommutative spaces. By connecting advanced algebraic topology to noncommutative topology, we opened up new methods for analysing noncommutative spaces. Some of my results can be used for advanced undergraduate and graduate courses.
Sectors Education