Dr Yemon ChoiLecturer in Pure Mathematics
The keyword version
Banach and operator algebras. Noncommutative harmonic analysis. Categorical and homological perspectives on functional analysis.
The longer version
I am interested in a range of topics and problems on the interface between algebra and functional analysis. This tends to be driven by particular families of examples, but my preference is for finding general frameworks that unify common features of these examples, once one has investigated individual examples in depth. "Hacking out lots of estimates and then trying to exploit functorial behaviour" is not the most accurate description, nor the most catchy one, but it gives some idea of what I spend my research time doing.In recent years I have worked intensively on various aspects of the Fourier algebras of locally compact groups: studying these objects involves a blend of (non-commutative) harmonic analysis and representation theory. Many of the developments over the last 20 years or so use the tools, or are guided by the philosophy, of the theory of operator spaces and completely bounded maps -- these may be thought of as enriched versions of Banach spaces and linear maps between them, where one allows matricial coefficients and not just scalar ones.
I am also interested in algebras of convolution operators arising from the canonical representation(s) of a group G on the Banach space Lp(G). When p=2 there is a rich theory available, from the world of C*-algebras and von Neumann algebras; for other values of p many basic structural questions remain unresolved, even for very explicit examples such as G=SLn(R) or SLn(Z).
Postgraduate Tutor for Research Students (Mathematics)
Departmental Academic Officer
Departmental Study Abroad Tutor (from Oct. 2018)
PhD Supervisions Completed
Mahmood Alaghmandan, 2013. (Supervised at the University of Saskatchewan, Canada, joint with E. Samei)
Jan. 2014 - present: Lecturer at Lancaster University, United Kingdom
Aug. 2010 - Jan. 2014: Assistant Professor (tenure-track), University of Saskatchewan, Canada
Aug. 2008 - Jul. 2010: Postdoctoral researcher, Universite Laval, Canada
Feb. 2007 - Jul. 2008: Postdoctoral fellow, University of Manitoba, Canada
Sept. 2002 - Jun. 2006: PhD student, University of Newcastle upon Tyne, United Kingdom
Sept. 2001 - Jun, 2002: Editorial assistant, National Extension College, United Kingdom.
B.A. in Mathematics (2000, Cambridge).
CASM (2001, Cambridge).
PhD in Pure Mathematics (2006, Newcastle-upon-Tyne)
PhD Supervision Interests
I am interested in hearing from suitable applicants wishing to start in 2019-20 or later.
Current ideas for PhD projects
Here are four possible areas in which I would currently be willing to supervise: each of these is not a specific PhD project, but a setting in which there are various possible research problems that a student could work on. I hope to add more details, or links to more details, in the near future: if you would like to know more then please feel free to get in touch.
- Algebras of convolution operators on Lp spaces
- Cohomological invariants for Fourier algebras
- Homological algebra for dual Banach algebras and their modules
- Classification problems for l1-semigroup algebras
Themes 1 and 2 are likely to require some prior exposure to the basic theory of C*-algebras. However, some of the necessary background can be learned in the initial stages of the PhD, and depending on the individual strengths of an applicant there may be particular projects that require less functional-analytic machinery; some questions may be suitable for those with solid basic analysis and interests in the representation theory of finite groups.
It is possible that you are reading this and have had some exposure to various structural properties of Banach algebras known as "approximate amenability", "character amenability", or "module amenability". I will not, for the foreseeable future, supervise on any of these three, nor on any hybrid of these.
("Connes-amenability", on the other hand, is related closely to Theme 3 above, but be warned that this is an area with some nasty traps for the novice, primarily because dual Banach algebras are in some sense still not really understood.)
Some results on direct finiteness of group algebras
CAP and ITAP for group von Neumann algebras
- Analysis and Probability