Семинар на МЦМН
2025-06-03 14:00 - 15:30, 2025-06-06 14:00 - 15:30, 2025-06-10 14:00 - 15:30 (Europe/Sofia) | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
Семинарът на МЦМН продължава със серия от четири лекции на д-р Петър Далаков, както следва:
Дати: 3, 6, 10, 13-ти юни, 14:00 часа
Място: стая 403, ИМИ-БАН
Лектор: Петър Далаков (ИМИ и АУБГ)
Тема: Special Kaehler Geometry and some applications
Резюме: In this short sequence of lectures we will discuss the notion of special Kaehler structure and some of its links to complex algebraic geometry, in particular, complex Lagrangians, variations of Hodge structures and algebraic integrable systems. The sequence will conclude with examples related to various moduli spaces of Higgs bundles on curves.
Повече информация можете да намерите на страницата на семинара:
https://icms.bg/category/icms-seminar/

Семинар на МЦМН
2025-06-06 14:00 - 17:00
The ICMS Seminar will meet this Friday, June 6-th, at 14:00, with three lectures by
Peter Dalakov, Lyudmil Katzarkov and Ernesto Lupercio from IMI-BAS.
The schedule is the following.
June 6-th. Room 403 IMI-BAS.
14:00 – 14:50. Peter Dalakov
Special Kaehler Geometry and some applications (Part II)
15:00 – 15:50. Lyudmil Katzarkov
Atoms and Minimal Model Program
16:00 – 16:50. Ernesto Lupercio
Elliptic genus and applications
Abstracts and more information can be found at
https://icms.bg/category/icms-seminar/

Семинар на МЦМН
2025-06-13 14:00 - 17:00
Семинарът на МЦМН продължава със серия от четири лекции на д-р Петър Далаков, както следва:
Дата: 13-ти юни
Място: стая 403, ИМИ-БАН
14:00 – 15:30. Peter Dalakov
Special Kaehler geometry and some applications (Part IV)
16:00 – 17:00. Ernesto Lupercio
Elliptic genera and the geometry of loop spaces and applications
Резюмета и допълнителна информация можете да намерите на страницата на семинара:
https://icms.bg/category/icms-seminar/

Семинар на МЦМН
2025-06-20 15:30 - 18:00
Следващото заседание на семинара на МЦМН ще се състои в петък, с доклади на Алексанър Стоколос и Ернесто Луперсио.
ICMS Seminar
Friday, June 20-th. Room 403 IMI-BAS.
15:30 – 16:30. Alexander Stokolos (Georgia Southern University)
On extremal polynomials
Abstract: I will present known and new polynomials emerging from the extremal problems of geometric complex analysis.
16:45 – 17:45. Ernesto Lupercio (IMI-BAS and Cinvestav IPN México)
Analysis in Loop Spaces and Genera
Abstract: Analysis on loop spaces, motivated by ideas from conformal field theory, leads naturally to the construction of elliptic genera—topological invariants with deep modular and representation-theoretic properties.
Мore information can be found at the seminar’s website
https://icms.bg/category/icms-seminar/

Семинар на МЦМН
2025-11-04 13:00 - 14:30
Семинар на МЦМН
Вторник, 4.11.2025, 13:00 ч., Зала 403, ИМИ – БАН
Лектор: Leonardo Cavenaghi (МЦМН, ИМИ – БАН)
Тема на доклада: Exotic phenomena in topology and geometry

Резюме: This talk, aimed at a general audience of mathematicians, discusses very geometric models of exotic spheres.
Exotic spheres are manifolds homeomorphic to classical spheres but not diffeomorphic to them. We will outline some constructions via group actions and discuss their admissible geometries. For instance, until this day, it is not known whether an exotic sphere admits a metric of positive sectional curvature, but some do not even admit positive scalar curvature.
In this talk, we also outline how one can indirectly study their geometries, aiming to gain a better understanding of their admissible geometries, for example, regarding the existence of Lorentzian metrics and the spectral problem.

Съвместно заседание на Семинара по особености и Семинара на МЦМН
2025-11-18 13:00 - 15:30
Joint meeting of the Seminar on Singularities and the ICMS Seminar, with a lecture by Pablo Cuadrado. The program is as follows.

Tuesday, November 18, room 403, IMI-BAS.

13:00 — Giovane Galindo (ICMS, IMI-BAS)
Bundle-type sub-Riemannian structures on holonomy bundles

14:00 — Pablo Portilla Cuadrado (Universidad Politécnica de Madrid)
The medial axis of the Milnor fiber

Abstract (Galindo): In this talk we present the notion of Gromov-Hausdorff distance, a novel field of study that aims to understand the topology of the moduli space of Riemannian metrics on a given manifold. We will then present new results on the subject concerning the collapse of principal bundles onto reductive homogeneous spaces.

Abstract (Cuadrado): Let f(x,y) define an isolated singularity at the origin. In this talk we explore a new flat metric induced on the Milnor fiber of f by the associated complex Hamiltonian vector field. With the help of this metric we can define a spine on each Milnor fiber via the classical method of the medial axis. This spine depends on the choice of boundary for the Milnor fiber. It is subanalytic and comes equipped with a retraction from the boundary onto it. We hope to understand the geometry of the versal unfolding space via these spines. This ongoing joint work with Norbert A’Campo.

Семинар на МЦМН
2025-11-25 13:00 - 14:30
Вторник, 25 ноември 2025 г., 13:00, room 403, IMI-BAS.

Deepanshu Prasad (МЦМН, ИМИ – БАН)
An Extension of Sato-Kimura Theorem for Semi-invariant rings

Резюме: We give an analog of a result of Sato-Kimura in the context of a semi-invariant ring for a finite dimensional algebra over an algebraically closed field K of characteristics 0. Then, we examine the case of finite dimensional hereditary algebras over K. This is joint work with Charles Paquette and David Wehlau.

An Extension of Sato-Kimura Theorem for Semi-invariant rings, ICMS seminar talk by Deepanshu Prasad

Съвместно заседание на семинара на МЦМН и семинара на секция МОИ
2025-11-26 16:00 - 17:30
26 ноември 2025 г., сряда, от 16:00 ч. в Зала 403 на ИМИ – БАН.
Съвместно заседание на Семинара на МЦМН и Семинара на секция Математически основи на информатиката
Frank Vallentin (Universität zu Köln)
Least distortion Euclidean embeddings of flat tori
Резюме: In the emerging field of bi-Lipschitz invariant theory, one studies embeddings of orbit spaces H/G (H a Hilbert space, G a subgroup of its automorphisms) into simpler Hilbert spaces via distance-preserving maps up to a constant factor.

In this talk, I present an infinite-dimensional semidefinite program that computes least-distortion embeddings of flat tori Rn/L, where L is an n-dimensional lattice, into Hilbert spaces. Using symmetry reduction techniques, this infinite-dimensional semidefinite program reduces to an infinite-dimensional linear program.
Even with this simplification, solving the program remains challenging. By combining this approach with the linear programming bound for spherical designs, combined with brute-force methods, we finally are able to determine the least-distortion embeddings of Rn/Zn, R2/A2, and R8/E8.
(Based on joint work with Arne Heimendahl, Moritz Lücke, Philippe Moustrou, and Marc Christian Zimmermann)

Least distortion Euclidean embeddings of flat tori, ICMS seminar talk by Frank Vallentin

Семинар на МЦМН и съвместно заседание със семинара АГТ
2025-12-02 13:00 - 16:00
Следващото заседание на семинара на МЦМН ще се състои във вторник, 2 декември 2025 г. Доклади ще изнесат Рой Маген от МЦМН и Ливиу Орнеа от Букурещския университет, като вторият доклад е в рамките на съвместно заседание със семинара на секция “Анализ, Геометрия и Топология”. Програмата е следната.

ICMS Seminar and AGT Seminar

Tuesday, December 2nd, room 403 IMI-BAS.

13:00 — Roy Magen (ICMS, IMI-BAS)

Flavours of homotopy theory

14:00 — Liviu Ornea (University of Bucarest)

Distinguished non-Kähler metrics on compact complex manifolds

Abstract (Magen):
In this talk we will consider different flavours of homotopy theory for different types of geometric contexts. First we will recall the usual definitions of the homotopy category, and equivariant homotopy categories, and we will show how we can think of these in terms of (equivariant) smooth manifolds. This will give us a suitable framework with which to adapt the notion of homotopy theory to different geometries.
We first use this framework to give a brief overview of the story in algebraic geometry, which produces motivic homotopy theory. Next, we will use our framework to discuss notions of homotopy theories parametrized by a geometric object, and discuss some consequences.
Depending on time constraints and interest, we will end either by discussing work relating this homotopical framework to 6-functor formalisms, by going over a version of this story in the complex analytic setting, or by introducing C∞-schemes and discussing possibilities for an extension of the story for manifolds to this setting.
Abstract (Ornea):

I shall review the definitions of LCK, pluriclosed and balanced metrics and discuss their incompatibility on the same compact complex manifold.

Семинар на МЦМН
2026-01-20 13:00 - 14:30
Дата и място: Вторник, 20.01.2026 г., 13:00 ч., Зала 403, ИМИ – БАН
Докладчик: Bogdan Đorđević (Serbian Academy of Arts and Sciences)
Заглавие: Applications of Banach algebras and Banach modules to some contemporary analysis problems
Abstract:
In recent years applied mathematics has experienced a historical progress, blurring the lines between the previously clear research paths and directions. Accordingly, contemporary mathematical analysis is at the verge of unifying seemingly different research areas and topics. With this in mind, I’d like to talk about my humble contribution to this cause: my lecture will concern how Banach algebras and modules, combined with spectral theory, functional calculus, and generalized inverses, help in various problems that emerge in applied mathematics in general: from solving operator and matrix equations, to evaluating sums of some Banach-space-valued series, to analyzing some unstable abstract Cauchy problems, and finally to approximating solutions to functional stochastic differential equations.
Допълнителна информация можете да намерите на сайта на семинара:
https://icms.bg/category/icms-seminar/

Семинар на МЦМН
2026-01-27 13:00 - 14:30
Дата и място: Вторник, 27.01.2026 г., 13:00 ч., Зала 403, ИМИ – БАН
Докладчик: Jean-Pierre Gazeau (Université Paris Cité, CNRS, and University of Białystok)
Заглавие: Spectral and angular variables for open qudit dynamics
Abstract: In this talk, I introduce a parametrization of finite-dimensional quantum states that is particularly adapted to the study of open qudit dynamics. Any generic density matrix in Cn can be described by separating spectral variables, which encode the eigenvalue content, from angular variables associated with the unitary degrees of freedom. These angular variables naturally live on the coset space SU(n)/T, in the spirit of the Tilma–Sudarshan construction.
A key outcome of this parametrization is a partial decoupling of the GKLS evolution: while the angular variables are driven by both the Hamiltonian and the dissipative contributions, the spectral variables evolve under the dissipative part only. This separation provides a transparent geometric picture of decoherence and dissipation. Simple examples for qubits and qutrits are discussed, together with an alternative, geometrically motivated notion of purity expressed solely in terms of the spectral variables in a linear way.
Допълнителна информация можете да намерите на сайта на семинара:
https://icms.bg/category/icms-seminar/

Семинар на МЦМН
2026-03-10 13:00 - 14:30, 2026-03-17 13:00 - 14:30
Two lectures by Milen Yakimov,
chair of the group on Cluster Algebras and Quantum Groups at the ICMS, IMI-BAS.

Tuesday, March 10, at 13:00 in room 403, IMI-BAS.
Cluster structures on quantum groups and the full Berenstein-Zelevinsky conjecture

Tuesday, March 17, at 13:00 in room 403, IMI-BAS.
Reflective centres of module categories and quantum K-matrices

Abstracts:
March 10: Cluster Algebras were invented by Fomin and Zelevinsky in the early 2000s and quickly turned into an indispensable tool in many areas of mathematics. In this talk, we will provide a gentle introduction to the subject. From the early days of the theory of cluster algebras, one of the desired constructions was to turn the quantized coordinate rings of complex simple Lie groups into quantum cluster algebras. This remained elusive. We will present a resolution of this conjecture and of the Berenstein-Zelevinsky conjecture on cluster structures on quantum double Bruhat cells. This is a joint work with Fan Qin and Hironori Oya.

March 17: Braided monoidal categories have applications in various situations. In particular, their universal R-matrices give solutions of the quantum Yang-Baxter equation and representations of braid groups of type A. There are powerful methods for constructing them: Drinfeld doubles of Hopf algebras and Drinfeld centres of monoidal categories. On the other hand, universal K-matrices, leading to solutions of the reflection equation and representations of braid groups of type B are much less well understood and there are no general constructions for them. We will describe a construction of reflective centers of module categories. It gives rise to a quantum double construction for universal K-matrices, which can be viewed as a type B analog of Drinfeld’s double construction. This is a joint work with Robert Laugwitz and Chelsea Walton.

More information can be found on the seminar’s web-page:
https://icms.bg/category/icms-seminar/

Семинар на МЦМН
2026-05-12 13:00 - 14:30
Дата и място: Tuesday, May 12-th, 13:00, room 403 IMI-BAS.
Лектор: Ina Petkova (Darmouth College)
Заглавие: Khovanov homology and Lagrangian cobordisms
Резюме: We provide a partial answer to a question of Ekholm, Honda, and Kalman about the relationship between Khovanov homology and decomposable Lagrangian cobordisms. We also utilize previously defined filtered invariants to give a family of obstructions to decomposable Lagrangian cobordisms from Khovanov homology. Joint with Gage Martin and Zachary Winkeler.

За допълнителна информация:
https://icms.bg/khovanov-homology-and-lagrangian-cobordisms-icms-seminar-talk-by-ina-petkova/
https://icms.bg/category/icms-seminar/

Съвместен семинар на МЦМН и секция АГТ
2026-06-02 13:00 - 14:30
Date and time: Tuesday, June 2-nd, 2026, 13:00, room 403 IMI-BAS
Lecturer: Bogdan Djordjevic, (Serbian Academy of Arts and Sciences, visitor at ICMS, IMI-BAS)
Title: Application of the Laplace transform for evaluating sums of hyperharmonic-like series in Banach algebras and modules
Abstract: In this talk it will be shown how the Laplace transform (in respective Banach spaces) can be utilized for evaluating sums of Banach-space-valued series. We demonstrate the technique on various abstract generalizations of the numerical hyperharmonic series, including noncommutative setting and non-invertible setting. As an application, we obtain new necessary consistency condition for the Sylvester equation ()ax-xb=c[latex].

Семинар на МЦМН
2026-06-09 13:00 - 14:30
Дата и място: вторник, 9 юни 2026 г., 13:00, зала 403, ИМИ-БАН.
Лектор: Azur Đonlagić (Université Paris-Saclay
Заглавие: Brauer-Manin Obstructions for Homogeneous Spaces
Резюме: In this talk, we introduce Brauer-Manin obstructions to the Hasse principle and to weak/strong approximation of adelic points on varieties over a global field. We also define variants of these obstructions well-suited for the study of rational points on homogeneous spaces of affine algebraic groups.
We then state the main questions considered in this theory and give an account of some developments, including the speaker’s recent work. Finally, we present briefly the main tools and ideas used in the theory, such as arithmetic duality theorems, highlighting the difficulties which appear in positive characteristic.

За допълнителна информация:
https://icms.bg/brauer-manin-obstructions-for-homogeneous-spaces/
https://icms.bg/category/icms-seminar/
