North Atlantic Noncommutative Geometry Seminar

13 listopada 2024 17:15
JONAS SCHNITZER (Università di Pavia, Italy)
THE QUANTIZATION OF MOMENTUM MAPS AND ADAPTED FORMALITY MORPHISMS (THE QUANTIZATION OF MOMENTUM MAPS AND ADAPTED FORMALITY MORPHISMS)
If a Lie group acts on a Poisson manifold by Hamiltonian symmetries, there is a well-understood way to get rid of unnecessary degrees of freedom and pass to a Poisson manifold of a lower dimension. …

6 listopada 2024 17:15
RALF MEYER (Georg-August Universität Göttingen, Germany)
CORRESPONDENCES BETWEEN GRAPH C*-ALGEBRAS (CORRESPONDENCES BETWEEN GRAPH C*-ALGEBRAS)
We describe proper correspondences from graph C*-algebras to arbitrary C*-algebras by K-theoretic data. If the target C*-algebra is a graph C*-algebra as well, we may lift an isomorphism and its inverse on a certain invariant …

30 października 2024 17:15
JOHN QUIGG (Arizona State University, Tempe, USA)
THE LADDER (THE LADDER)
We present a new method of establishing a bijective correspondence - in fact, a lattice isomorphism - between invariant ideals of C*-algebras and their crossed products by a fixed locally compact group. It was already …

23 października 2024 17:15
SUGATO MUKHOPADHYAY (SISSA, Trieste, Italy)
ALGEBRAIC AND SPECTRAL TORSIONS ON THE ALMOST COMMUTATIVE GEOMETRY OF DOUBLED MANIFOLDS
I will present a construction of a noncommutative second order differential calculus on the algebra of smooth functions on the product of a manifold with the two-point space. This involves a modification of the standard …

16 października 2024 17:15
FRANCESCO D'ANDREA (Università di Napoli Federico II, Italy)
VAKSMAN-SOIBELMAN ODD QUANTUM SPHERES AND COMPLEX QUANTUM PROJECTIVE SPACES REVISITED
Odd-dimensional quantum spheres were introduced in 1990 by Vaksman and Soibelman as quantum homogeneous spaces of Woronowicz's quantum unitary groups. Since then, they have served as major examples for testing ideas about non-commutative spaces. In …

9 października 2024 17:15
RITA FIORESI (Università di Bologna, Italy)
REDUCTIONS OF QUANTUM PRINCIPAL BUNDLES
We develop the theory of reductions of quantum principal bundles over projective bases. We show how the sheaf-theoretic approach can be effectively applied to certain relevant examples such as the Klein model for the projective …

2 października 2024 17:15
CRISTIAN IVANESCU (MacEwan University, Edmonton, Canada)
THE CUNTZ SEMIGROUP AND THE STRUCTURE OF C*-ALGEBRAS
The Cuntz semigroup, introduced over 40 years ago by J. Cuntz, has become a valuable tool for understanding the structure of C*-algebras. Building on A. Toms’ pioneering work in the early 2000s, which produced the …

12 czerwca 2024 17:15
VALERIO PROIETTI (Universitetet i Oslo, Norway)
GROUPOIDS WITH TORSION-FREE ISOTROPY AND THEIR INVARIANTS
I will introduce groupoids with torsion-free isotropy and several (topological) dynamical systems of interest which give rise to groupoids in this class. We will apply methods from homotopy theory to study the K-theory of the …

5 czerwca 2024 17:15
PAULA S. E. MOREIRA (Universidade Federal de Santa Catarina, Florianópolis, Brazil)
THE IDEAL STRUCTURE OF PARTIAL SKEW GROUPOID RINGS WITH APPLICATIONS TO TOPOLOGICAL DYNAMICS AND ULTRAGRAPH ALGEBRAS
Given a partial action α of a groupoid G on a ring R, we study the associated partial skew groupoid ring with its natural G-grading. In this talk, we will characterize primeness, simplicity, and the …

29 maja 2024 17:15
GENNADI KASPAROV (Vanderbilt University, Nashville, USA)
ORBITAL AND TRANSVERSE INDEX THEORY FOR A PROPER LIE-GROUP ACTION
For the index theory of elliptic operators on a compact manifold X, the standard choice of a symbol algebra for (scalar) operators of negative order is C0(TX). The zero-order symbols are bounded multipliers of this …

22 maja 2024 17:15
ARKADIUSZ BOCHNIAK (Max Planck Institut für Quantenoptik, Garching, Germany)
FROM THE MYCIELSKI CONSTRUCTION TO QUANTUM TWINS
Graph theory is not only of great importance in mathematics, but also has an enormous number of applications in other branches of science. In particular, it is a key ingredient in modeling noisy communication channels. …

15 maja 2024 17:15
ALISTAIR MILLER (Syddansk Universitet, Odense, Denmark)
CORRESPONDENCES, HOMOLOGY AND K-THEORY FOR ÉTALE GROUPOIDS
One approach to understanding the K-theory of an étale groupoid C*-algebra is to approximate it with the groupoid homology. I will describe the functoriality of the K-theory, the homology and the approximation with respect to …

8 maja 2024 17:15
STEFAN WAGNER (Blekinge Tekniska Högskola, Karlskrona, Sweden)
FACTOR SYSTEMS AS A COMPUTATIONAL FRAMEWORK FOR NONCOMMUTATIVE PRINCIPAL BUNDLES
Free actions in the sense of Ellwood provide a natural framework for C*-algebraic noncommutative principal bundles, which are becoming increasingly prevalent in various applications to noncommutative geometry and mathematical physics. One of the key features …

24 kwietnia 2024 17:15
LUCAS HALL (University of Haifa, Israel)
TOPOLOGICAL CLASSIFICATION OF SKEW PRODUCTS FOR QUIVER C*-ALGEBRAS
I will present a topological version of the combinatorial skew product for graphs, show how this designs a natural coaction on the C*-algebra associated to a topological quiver, and show natural criteria for identifying an …

17 kwietnia 2024 17:15
TOMASZ BRZEZIŃSKI (Prifysgol Abertawe, Cymru)
HOPF HEAPS AND HOPF ALGEBRAS OF TRANSLATIONS
Grunspan and Schauenburg have proven that quantum torsors (introduced by the former) are closely connected with Hopf-Galois objects. In this talk, I will present, in part, the dualisation of this connection and, in part, a …