| Date: | Thursday, 5th February 2026 |
| Speaker: | Dr Anna Duwenig (University of New South Wales, Australia) |
| Title: | The Zappa–Szép product of groupoid twists |
| Abstract: | The Zappa–Szép (ZS) product of two groupoids is a generalisation of the semi-direct product: instead of encoding one groupoid action by homomorphisms, the ZS product groupoid encodes two (non-homomorphic, but "compatible") actions of the groupoids on each other. Together with my collaborator Boyu Li, I have been working on various ways of generalising this construction to the world of C*-algebras. In this talk, I will introduce you to our generalisation of the ZS product to two twists over groupoids and, if time permits, I will show how our construction ties in with Weyl twists from Cartan pairs arising from Kumjian–Renault theory. (Based on joint work with Boyu Li, New Mexico State University.) |
| — [No seminar on 12th February 2026.] — | |
| Date: | Thursday, 19th February 2026 |
| Speaker: | Dr Aleksa Vujičić (University of Waterloo, Canada) |
| Title: | The Fourier spine of Fell groups |
| Abstract: | For a locally compact group G, one can define the Fourier and Fourier–Stieltjes algebras A(G) and B(G), which in the abelian case are isomorphic to L1(Ĝ) and M(Ĝ) respectively. While there is no direct analogue in the general case, they do share similar properties, so typically A(G) is more "tractable" than B(G) and often easier to describe. The notable exception is when G is compact, in which case these algebras coincide. The Fell group, defined as G = Qp ⋊ Op* (where Qp and Op denote the p-adic numbers and integers respectively), has very compact-like behaviour in many regards. In particular, B(G) is small: it can be written as the direct sum B(G) = A(G) ⊕ A(Op*). The combination of all direct sums of this form is known as the "spine" of B(G), and the Fell group is one of a few known non-compact examples of a group where the spine of B(G) is B(G) itself. Based on joint work with Nico Spronk, we investigate the structure of B(G) for higher dimensional analogues of the Fell group. Although B(G) is larger than its spine in these groups, we find that this difference is rather small in some sense. |
| — [No seminar on 26th February 2026.] — | |
| — [No seminar on 5th or 12th March 2026 due to MATRIX Workshop.] — | |
| Date: | Thursday, 19th March 2026 |
| Speaker: | Dr Adam Dor-On (Haifa University, Israel) |
| Title: | Distance to commuting unitary matrices |
| Abstract: | TBA |
| Date: | Thursday, 26th March 2026 |
| Speaker: | Dr Adam Dor-On (Haifa University, Israel) |
| Title: | TBA |
| Abstract: | TBA |
| Date: | Thursday, 2nd April 2026 |
| Speaker: | Ryan Thompson (Victoria University of Wellington, New Zealand) |
| Title: | TBA |
| Abstract: | TBA |
| — [No seminar on 9th or 16th April 2026 due to Mid-Trimester Break.] — | |
| Date: | Thursday, 23rd April 2026 |
| Speaker: | TBA |
| Title: | TBA |
| Abstract: | TBA |
| Date: | Thursday, 30th April 2026 |
| Speaker: | TBA |
| Title: | TBA |
| Abstract: | TBA |
| Date: | Thursday, 7th May 2026 |
| Speaker: | TBA |
| Title: | TBA |
| Abstract: | TBA |
| Date: | Thursday, 14th May 2026 |
| Speaker: | TBA |
| Title: | TBA |
| Abstract: | TBA |
| Date: | Thursday, 21st May 2026 |
| Speaker: | TBA |
| Title: | TBA |
| Abstract: | TBA |
| Date: | Thursday, 28th May 2026 |
| Speaker: | TBA |
| Title: | TBA |
| Abstract: | TBA |