Thursday 22 October 2026 from 11 am, as part of the Al@Bicocca seminar cycle, Oussama Hamza e Zhizheng Yu (Harbin Institute of Technology) will hold the following talks
Speaker: Oussama Hamza
Title: Filtrations and Graph Products: Applications in Galois Theory and Arithmetic
Abstract: Graph products, filtrations, and cohomology rings provide useful tools for studying pro-p quotients of absolute Galois groups. I will first present my results, with Maire, Mináč, and Tân on formally real Pythagorean fields of finite type (RPF fields). In this work, a new class of groups, called Delta-Right Angled Artin groups, is introduced. This class provides a new necessary condition on pro-2 groups to be pro-2 maximal quotients of absolute Galois groups. I will then discuss pro-p extensions of number fields, when p is an odd prime, with restricted ramification and prescribed splitting. In the wild case (ramification containing places above p), joint work with Lim and Maire uses coproduct decompositions and Massey vanishing property to construct large unipotent extensions. In the tame case (ramification not containing places above p), analogously to knot theory, we have a notion of linking numbers for some of these extensions.
Joint work with Feuerpfeil and Lim answers a question of Labute on the realization of linking numbers and derive several cohomological consequences.
Speaker: Zhizheng Yu
Title: Commutator on Banach Spaces
Abstract: In this talk, we will review the historical development of research on commutators on Banach spaces, with a focus on characterizing whether a given Banach space is a Wintner space. Finally, we will demonstrate that Schatten p-spaces Cp, 1 ≤ p < ∞, are Wintner spaces. In particular, an operator T ∈ B(Cp) is a commutator in B(Cp) if and only if T − λI is is not Cp-strictly singular for every λ ≠ 0.
This talk is based onthe joint work with L. X. Cheng, J. H. Huang and F. Sukochev.
Information to attend
The seminar will be held in Room Alpha (DB1 Building, 3rd Floor | Deutsche Bank | Piazza del Calendario 3, Milano) and will also be available online by this link.
Those who wish to attend in person but are unable to access the DB1 building may contact the organisers at least 24 hours in advance at: albicocca@unimib.it
For more information, visit the website