North Atlantic Noncommutative Geometry Seminar

May 31, 2023, 5:15 p.m.
ROBERTO CONTI (Sapienza Università di Roma, Italy)
CLASSICAL SYMMETRIES OF NONCOMMUTATIVE SPACES: A GUIDED TOUR THROUGH THE CUNTZ ALGEBRA CASE
Multiplets of isometries with orthogonal ranges summing up to 1 were systematically used by Doplicher and Roberts in the early 70's  in their study of the superselection structure of Quantum Field Theory. Nowadays, the C*-algebra …

May 17, 2023, 5:15 p.m.
SOUMALYA JOARDAR (Indian Institute of Science Education and Research Kolkata, India)
EQUIVARIANT C*-CORRESPONDENCE
Let G be a compact quantum group. Then upon introducing the notion of a G-equivariant C*-correspondence and a G-C*-algebra, we shall show that a G-equivariant C*-correspondence makes the associated Pimsner algebra a G-C*-algebra. Moreover, for a Kac-type compact quantum group G, under …

May 10, 2023, 5:15 p.m.
DEVARSHI MUKHERJEE (Universidad de Buenos Aires, Argentina)
THE HOMOTOPY K-THEORY FOR NON-ARCHIMEDEAN BORNOLOGICAL ALGEBRAS
I will define non-Archimedean bivariant K-theory. This is the target of the universal functor on the category of complete, torsion free bornological Zp-algebras that satisfies homotopy invariance, stability and excision, and is a non-Archimedean analogue of …

April 26, 2023, 5:15 p.m.
JULIEN BICHON (Université Clermont Auvergne, France)
THE FAITHFUL FLATNESS OF HOPF ALGEBRAS OVER COIDEAL SUBALGEBRAS WITH CONDITIONAL EXPECTATION
Faithful flatness is an algebraic concept arising from algebraic geometry and closely related to the question of forming ''good'' quotients. Also, it plays a key role in the noncommutative world, especially in Hopf-algebra theory. After …

April 19, 2023, 5:15 p.m.
KONRAD AGUILAR (Pomona College, USA)
THE FELL TOPOLOGY AND THE MODULAR GROMOV-HAUSDORFF PROPINQUITY
Given a unital AF-algebra A equipped with a faithful tracial state, we endow each (norm-closed two-sided) ideal of A with a metrized quantum-vector-bundle structure. The ideals are canonically viewed as modules over A, in the sense of Latrémolière, using previous …

April 12, 2023, 5:15 p.m.
STEFAN WALDMANN (Universität Würzburg, Germany)
CONVERGENCE OF STAR PRODUCTS: OLD AND NEW
In this talk, I will explain the issue of convergence for formal star products. While the theory of formal deformation quantizations of general Poisson manifolds is well-understood and explored by many people, for physical applications, formal power series in h are …

April 5, 2023, 5:15 p.m.
SUTANU ROY (National Institute of Science Education and Research, India)
BRAIDED QUANTUM SYMMETRIES OF GRAPH C*-ALGEBRAS
In this talk, we will explain the existence of a universal braided compact quantum group acting on a graph C*-algebra in the twisted monoidal category of C*-algebras equipped with an action of the circle group. …

March 29, 2023, 5:15 p.m.
GILLES GONÇALVES DE CASTRO (Universidade Federal de Santa Catarina, Brazil)
INFINITE-SUM RELATIONS IN C*-ALGEBRAS
We build a universal C*-algebra using the strong operator topology to describe certain relations. In particular, this allows us to use infinite-sum relations. We show that these algebras have indeed a universal property, and then prove that …

March 22, 2023, 5:15 p.m.
JONATHAN M. ROSENBERG (University of Maryland, USA)
NONCOMMUTATIVE GEOMETRY AND DUALITY OF ORIENTIFOLD FIELD THEORIES
An important phenomenon in modern physics is that, often, very different field theories give rise to identical physical predictions. This is what physicists usually call “duality”, though it does not always agree with the mathematical …

March 15, 2023, 5:15 p.m.
ILYA SHAPIRO (University of Windsor, Canada)
CYCLIC HOMOLOGY, COEFFICIENTS, AND LIMITS
Classically, coefficients for Hopf-cyclic homology were defined as objects that are both a module and a comodule with a compatibility between the two structures. This definition has been generalized to different settings with various levels …

March 8, 2023, 5:15 p.m.
MAYUKO YAMASHITA (RIMS, Kyoto University, Japan)
TOPOLOGICAL MODULAR FORMS AND VANISHING OF HETEROTIC ANOMALY
In this talk, based on my work with Yuji Tachikawa, I will explain how to use algebraic topology to solve the physical problem of vanishing anomalies in heterotic string theories. We translate this physical problem …

March 1, 2023, 5:15 p.m.
ARUP KUMAR PAL (Indian Statistical Institute, Delhi Centre, India)
CRYSTALLIZATION OF THE C*-ALGEBRA C(SUq(n+1))
We will explain how to obtain the crystal limit of the C*-algebra of continuous functions on the quantum SU(n+1) group as a C*-algebra given by generators and relations. These relations are derived by looking at …

Feb. 22, 2023, 5:15 p.m.
TOMASZ MASZCZYK (University of Warsaw, Poland)
HOCHSCHILD COHOMOLOGY FOR ABSTRACT CONVEXITY AND SHANNON ENTROPY
The Shannon entropy was introduced as a statistical measure of information loss but appeared in other fields of mathematics as well. We plan to sketch its relations with polylogarithms and motives after Cathelineau, Dupont, Bloch, …

Jan. 25, 2023, 5:15 p.m.
Piotr M. Hajac (IMPAN)
THE COVARIANT FUNCTORIALITY OF GRAPH ALGEBRAS
In the standard category of directed graphs, morphisms respect the lengths of paths. However, this requirement is way too strong to present natural *-homomorphisms between graph C*-algebras as covariantly induced from morphisms of graphs, so …

Jan. 18, 2023, 5:15 p.m.
HUA WANG (IMPAN)
CONSTRUCTIONS OF QUANTUM GROUPS WITH THE RAPID DECAY PROPERTY
Starting with Haagerup's seminal work, the rapid decay (RD) property was systematically studied by Jolissaint for discrete groups, and later by Vergnioux, in the setting of discrete quantum groups. Through the work of many hands, …