Institute of Mathematics and Informatics

Общ семинар на секция "Анализ, геометрия и топология" и МЦМН
2025-07-15 13:00 - 14:30 (Europe/Sofia) | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
На 15 юли 2025 г. от 13:00 часа в зала 403 на ИМИ-БАН ще се проведе съвместно заседание на Общия семинар на секция “Анализ, геометрия и топология” и Международния център по математически науки (ICMS-Sofia).
Доклад на тема:
Weak Metric Structures on Generalized Riemannian Manifolds
ще изнесе Milan Zlatanovic, University of Niš, Serbia.
Резюме. Linear connections with torsion are important in the study of generalized Riemannian manifolds ((M), (G=g+F)), where the symmetric part (g) of (G) is a non-degenerate (0,2)-tensor and (F) is the skew-symmetric part. Some space-time models in theoretical physics are based on ((M, G=g+F)), where (F) is defined using a complex structure. In the lecture, we will show more general models, where (F) has constant rank and is based on weak metric structures (introduced by the V. Rovenski and R. Wolak), which generalize almost contact and (f)-contact structures. We consider metric connections (i.e., preserving (G)) with totally skew-symmetric torsion tensor. For (mbox{rank}(F)= mbox{dim} M) and non-conformal tensor (A^2), where (A) is a skew-symmetric (1,1)-tensor adjoint to (F), we apply weak almost Hermitian structures to fundamental results (by S. Ivanov and M. Zlatanovic) on generalized Riemannian manifolds and prove that the manifold is a weighted product of several nearly Kahler manifolds corresponding to eigen-distributions of (A^2). For (mbox{rank}(F)< mbox{dim} M) we apply weak (f)-structures and obtain splitting results for generalized Riemannian manifolds.
(This is joint work with Vladimir Rovenski, Department of Mathematics, University of Haifa).
Посещението на лектора е финансирано по Научна програма “Повишаване на изследователския капацитет в областта на математическите науки (ПИКОМ)”, № ДО1-67/05.05.2022.

Семинар по геометрия на МЦМН
2025-07-09 16:00 - 17:30 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
Следващата сбирка на Семинара по геометрия на МЦМН ще се състои в сряда, 9 юли, от 16:00 ч. в зала 403 и онлайн в Zoom:

https://icms.bg/around-combinatorial-viros-patchworking-geometry-seminar-talk-by-arthur-renaudineau/

Zoom link:
https://us02web.zoom.us/j/86186281353?pwd=[REDACTED]

Семинар "Математически основи на информатиката"
2025-07-03 14:30 - 16:00 | Великотърновски университет, ул. "Теодосий Търновски" № 2, Велико Търново, 5005, Bulgaria
Семинарът по
МАТЕМАТИЧЕСКИ ОСНОВИ НА ИНФОРМАТИКАТА
организиран от
Секция „Математически основи на информатиката“ към ИМИ – БАН и
Факултет „Математика и информатика“ – ВТУ,
Ви кани на поредната сбирка на 3 юли 2025 г. от 14:30 часа в зала 508 на учебен корпус 4 на ВТУ, на която
Светослава Минкова
магистърска програма
„Математически структури в информационната сигурност“
ФМИ, Великотърновски университет
ще изнесе доклад на тема:
Weisfeiler-Leman алгоритъм и инварианти за изоморфизъм на графи

Защита на дисертация за ОНС "доктор" на Светозар Станков
2025-06-24 14:00 - 16:00 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
Институтът по математика и информатика при БАН и Научното жури за присъждане на образователна и научна степен “доктор” съобщават, че
на 24 юни 2025 г. от 14:00 ч., в зала 256 на ИМИ-БАН и в Zoom ще се проведе открито заседание на Научното жури по защита на дисертационен труд на тема:
Симетрия и метрична геометрия в банахови пространства
на
Светозар Станков
в област на висше образование: 4. Природни науки, математика и информатика; професионално направление:
4.5. Математика; докторска програма: „Математически анализ“
Научен ръководител:
проф. дмн Денка Куцарова
Председател на Научното жури:
акад. Юлиан Ревалски
Членове на Научното жури:

акад. Станимир Троянски
проф. дмн Михаил Кръстанов
проф. д-р Людмила Николова
доц. д-р Милен Иванов
Материалите по защитата са на разположение в библиотеката на ИМИ-БАН и са публикувани на интернет страницата на ИМИ:
http://www.math.bas.bg/omi/IMIdocs/ZRASRB/degrees_phd_current.php
Zoom link към заседанието за защитата:
https://us02web.zoom.us/j/81066909246?pwd=[REDACTED]

Семинар на МЦМН
2025-06-20 15:30 - 18:00 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
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/

International Conference BIOMATH 2025
2025-06-15 - 2025-06-20 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
BIOMATH 2025
International Conference on Mathematical Methods and Models in Biosciences and a School for Young Scientists,
15 – 20 June 2025, Sofia, Bulgaria
The annual international conference on Mathematical Methods and Models in Biosciences (Biomath) will take place from 15 to 20 June 2025 at the campus of the Bulgarian Academy of Sciences in the Institute of Mathematics and Informatics (IMI) and the Institute of Mechanics. Biomath 2025 is devoted to recent research in life sciences based on applications of mathematics as well as mathematics applied to or motivated by biological studies. It is a multidisciplinary meeting forum for researchers who develop and apply mathematical and computational tools to the study of phenomena in the broad fields of biology, ecology, medicine, biophysics, biochemistry, pharmacokinetics, chemoinformatics, biotechnology, bioengineering, environmental science, etc.
The conference continues a tradition of scientific meetings on Biomathematics since 1995 (see Biomath Conference Series). It is supported by several research units of the Bulgarian Academy of Sciences (such as the Institutes of Mathematics and Informatics, Information and Communication Technologies, Microbiology, Molecular Biology, Mechanics, Neurobiology, Biodiversity and Ecosystem Research, etc.) and several Universities (Sofia University “Kl. Ohridski”, Plovdiv University “Paisii Hilendarski”, South-West University “N. Rilski”), as well as the Union of the Bulgarian Mathematicians and the Biomath Forum. International partners of the Biomath series of conferences are the Department of Mathematics and Applied Mathematics and the DST/NRF SARChI Chair on Mathematical Models and Methods in Bioengineering and Biosciences at the University of Pretoria, and the Institute of Applied Mathematics at the University of Warsaw.
Biomath School for Young Scientists
The school comprises plenary lectures and sessions for contributed talks. The lectures at the school are of more introductory nature giving foundations and insight into the respective topic rather then focusing on new results and are presented by some of the keynote speakers of the conference. A central event for the school is the Hot Topics Workshop. Several scholars act as moderators, presenting “hot areas” and related open problems. All PhD students and young scientists participating in the conference are considered members of the school.
Detailed information can be found on the conference website: https://www.biomath.bg/2025/

Семинар на МЦМН
2025-06-13 14:00 - 17:00 | 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:
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
2025-06-10 14:00 - 15:30, 2025-06-06 14:00 - 15:30, 2025-06-03 14:00 - 15:30 | 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/

Международна конференция ``Singularities in Plovdiv"
2025-06-08 - 2025-06-13 | Пловдив
От 8 до 13 юни 2025 г.
в Пловдив ще се проведе
международна конференция “Singularities in Plovdiv”,
на която ще изнесат доклади водещи специалисти в теория на особеностите на теми свързани с нискоразмерна топология, теория на нормиранията, разрешаване на особености, теория на деформациите, динамични системи и др.
Конференцията се организира от Международния център по математически науки – София с подкрепата на Програма ПИКОМ, Фондация Саймънс, Швейцарска национална научна фондация, Математическия институт ,,Жусийо” – Париж.
Повече за конференцията можете да научите тук:
https://icms.bg/singularities-in-plovdiv-2025/

Семинар на МЦМН
2025-06-06 14:00 - 17:00 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
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 "Алгебра и логика"
2025-06-06 12:30 - 14:00 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
На 6 юни 2025 г. (петък) от 12:30 часа в зала 578 на ИМИ
и онлайн чрез платформата zoom ще се проведе хибридно заседание на семинара по „Алгебра и логика”.
Доклад на тема:
Holographic probe branes and artificial neural networks
ще изнесе
Веселин Филев (ИМИ-БАН).
Резюме: In holography, flavour probe branes are used to introduce fundamental matter to the AdS/CFT correspondence. At a technical level, the probes are described by extremizing the DBI action and solving the Lagrange–Euler equations of motion. I will report on applications of artificial neural networks that allow direct minimization of the regularized DBI action (interpreted as a free energy) without the need to derive and solve the equations of motion. I will consider, as examples, magnetic catalysis of chiral symmetry breaking and the meson melting phase transition in the D3/D7 holographic set-up.

Линк към zoom-стаята на семинара:
Https://us02web.zoom.us/j/85137375021?pwd=[REDACTED]
Поканват се всички желаещи да присъстват.
От секция „Алгебра и логика” на ИМИ – БАН
http://www.math.bas.bg/algebra/seminarAiL/
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Семинар по Приложна математика
2025-06-03 15:00 - 16:30 | Zoom
Следващата сбирка на Семинара по приложна математика ще се проведе на 03.06.2025 г. от 15:00 в онлайн среда:
Join Zoom Meeting
https://us02web.zoom.us/j/87588684853?pwd=[REDACTED]
Meeting ID: 875 8868 4853
Passcode: [REDACTED]
A generalization of Meijer’s G function motivated by probability
Докладчик: Dmitrii Karp
Резюме: Meijer’s G function appeared in probability in 1930-ies even before Meijer’s work as the density of the product of independent beta variables and as the density of the likelihood ratio test for samples drawn from many classical probability distributions. It is defined by a contour integral of the appropriate ratio of gamma products (sometimes reducible to the inverse Mellin transform). Replacing the Euler gamma function by the Barnes double gamma function in this contour integral, we introduce a new family of special functions which we call Mellin-Barnes’ K function. It is a quite general family which contains Meijer’s G function (thus also all classical hypergeometric functions pFq), as well as several new functions that appeared recently in the study of random processes and the fractional fenomena. For example, the running supremum of an alpha-stable Levy process has density expressible by K function as well as does the exponential functionals of the hypergeometric process. In the talk, we will discuss the definition of the new function, its basic analytic and transformation properties and relations to the functions found in the literature. We further define a generalization of the Kilbas-Saigo function introduced earlier to solve in closed form certain classes of integral and differential equations of fractional order and observe that both the original and the generalized Kilbas-Saigo functions are special cases of our new function.
The talk is based on a joint work with Alexey Kuznetsov (York University, Toronto, Canada).

"Защо да станете изследовател?" – срещи на френски математици с ученици и студенти
2025-06-02 16:30 - 2025-06-05 18:30 | Българска академия на науките, ул. „15 ноември“ №1, София, София-град, 1040, Bulgaria
От 2 до 5 юни 2025 г. в зала “Проф. Марин Дринов” на Българската академия на науките ще се проведат серия от срещи на изткнати френски математици с български ученици и студенти.

Лекциите ще се провеждат всеки ден (от понеделник до четвъртък) от 16:30 до 18:30 часа. Целта на тези беседи е да се популяризира кариерата на учен математик сред български ученици и студенти с подчертан интерес към математиката.

Лектори са:

Седрик Вилани, Филдсов медалист, член на Френската академия на науките, професор в Университета Клод Бернар-Лион 1.
Бернар Тесие, Математически институт “Жусийо”, Университет на Париж.
Патрик Попеску-Пампу, Университет на Лил.

Събитието се провежда под патронажа на Посолството на Франция в България и Френския институт в България и с подкрепата на НП “Образование с наука”. Организатори на събитието са ИМИ-БАН, СМБ, Ученическия институт на БАН и Френския институт в България.

Семинар "Дидактическо моделиране"
2025-06-02 14:35 - 16:00 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
Поредната сбирка на семинара
Дидактическо моделиране
ще се проведе на 02.06.2025 г. от 14:35 ч. в зала 278 на ИМИ.
Доклад на тема
Факториели на полиноми – ученическо изследване с обширна съвкупност от концепции в теория на числата
ще изнесe
Мирослав Маринов.

Семинар "Алгебра и логика"
2025-05-16 13:00 - 14:00 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
На 16 май 2025 г. (петък) от 13:00 часа в зала 503 на ИМИ
и онлайн чрез платформата zoom ще се проведе хибридно заседание на семинара по „Алгебра и логика”.
Доклад на тема:
Grätzer-Schmidt Theorem in arithmetical transfinite recursion
ще изнесе
Soowhan Yoon
(American University in Bulgaria).
Abstract: We assess the reverse mathematical strength of the Grätzer-Schmidt theorem (GS) as a principle in second order arithmetic. The theorem GS was studied in an article by Katie Brodhead, Mushfeq Khan, Bjørn Kjos-Hanssen, William A. Lampe, Paul Kim Long V. Nguyen, and Richard A. Shore, where they establish the provability of GS in Π11 Comprehension (Π11-CA0) and its restrictive variant GSD in arithmetical comprehension (ACA0). It will be shown that the arithmetical transfinite recursion (ATR0) is sufficient to prove GS. Additionally, other variants of GS will be explored as well. Some will be proved in ACA0, while others will be shown equivalent to ATR0 over ACA0. Then, we will discuss these results in the context of “Almost Theorems of Hyperarithmetic Analysis” (ATHA) by Shore in 2023.

Линк към zoom-стаята на семинара:
Https://us02web.zoom.us/j/85137375021?pwd=[REDACTED]
Поканват се всички желаещи да присъстват.
От секция „Алгебра и логика” на ИМИ – БАН
http://www.math.bas.bg/algebra/seminarAiL/
============================== =====================

Семинар на секция "Изследване на операциите, вероятности и статистика"
2025-05-14 15:00 - 16:30 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
На 14 май (сряда) от 15:00 ч. в зала 503 на ИМИ
ще се състои сбирка на Семинара на секция ИОВС. Доклад на тема:
Busy Beaver за n=5, или колко сложни са простите програми
ще изнесе д-р Георги Георгиев от ФМИ на СУ.
Резюме. Колко дълго може да работи машина на Тюринг с 5 състояния и азбука {0,1}, преди да спре?
В началото лентата е запълнена с нули.
Известна под името „Busy Beaver за n=5“ или BB(5), задачата е разбираема за всеки ученик, който се интересува от програмиране.
Решаването ѝ продължи 40 години и демонстрира колко сложен е семантичният анализ дори на микроскопични програми.
Историята бе разказана увлекателно преди година в списанието Quanta Magazine:
https://www.quantamagazine.org/amateur-mathematicians-find-fifth-busy-beaver-turing-machine-20240702/.
Ще разкажа за моето участие в решаването на задачата и за връзката ѝ с фундаменталните ограничения на методите за математическо и научно изследване.

Встъпителна лекция на доц. Михаил Школников
2025-05-13 15:15 - 16:30 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
Встъпителната лекция на доцент Михаил Школников в секция Анализ, геометрия и топология на ИМИ-БАН ще се проведе на 13.05.2025 г. (вторник) от 15:15 ч. в зала 403 на ИМИ – БАН.
Докладчик: Михаил Школников (ИМИ – БАН)
Доклад: Introduction to amoebas and tropicalization
Резюме: We will start by reviewing the most classical aspects of the theory of amoebas deeply rooted in complex analysis and geometry. Next, we will pass to the notion of a tropical limit of amoebas, and will see how restoring the phase allows to recover topology and deduce intersection-theoretic results. After that, we will discuss some results (and their limitations) obtained with Grigory Mikhalkin in the context of non-commutative versions of amoebas of surfaces and tropical limits of curves inside the special matrix group SL(2,C). I will conclude by sketching a proof of the complete description of possible tropicalizations of families of analytic surfaces in SL(2,C) recently obtained with Peter Petrov, in particular, motivating our ongoing project on the non-commutative phase tropicalization, a few words about which will be said if time permits.

Семинар на МЦМН
2025-05-13 14:00 - 15:15 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
Сбирка на семинара на МЦМН ще се проведе на 13.05.2025 г. (вторник) от 14:00 ч. в зала 403 на ИМИ – БАН.
Докладчик: Milan Zlatanovic (University of Niš)
Доклад: Non-symmetric gravitational theorys
Резюме: We will consider a connection with totally skew-symmetric torsion on non-symmetric (semi-) Riemann manifolds that satisfy Einstein’s metric condition (EMC). We proved that an almost Hermitian manifold is a non-symmetric Riemann manifold that satisfies EMC if and only if it is a Nearly Kahler manifold. We will also show what happens in the case of para Hermitian manifold, contact, and para-contact manifolds that satisfy EMC. We show that a connection with skew symmetric torsion satisfying EMC exists on an almost contact metric manifolds when it is D-homothetic to a cosymplectic manifold. We proved the structure theorem for the new class of almost contact metric manifold and special attention we have focused on dimension 5. As a natural continuation of this research, we dealt with the case of Lorentzian manifolds.
This is joint work with Stefan Ivanov and Nikola Stanchev.
Допълнителна информация: https://icms.bg/category/icms-seminar/

Семинар по геометрия на МЦМН
2025-05-07 16:00 - 17:30 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
Следващата сбирка на Семинара по геометрия на МЦМН
ще се проведе в сряда, 7 май 2025 г. от 16:00 ч. в зала 403 и онлайн в Zoom:
Доклад на тема
Binary Quadratic Forms and Conway’s Topographs (Lecture 2 of 3)

ще изнесе Nikita Kalinin, Guangdong Technion Israel Institute of Technology.

Следващата лекция ще бъде на 14.05.2025 от 16:00 ч.

Abstract: Binary quadratic forms are as elementary as they are mysterious—much like prime numbers. In 1997, John Conway introduced topographs, a powerful geometric tool that provides a geometric visualization of binary quadratic forms and their values. These lectures will explore how topographs, combined with telescoping summation techniques, yield elegant formulas — some with intuitive geometric interpretations. For instance, consider the following result:
Let
(A = big{ (x, y) mid x,yin mathbb{Z}_{geq 0}^2, det(x y) = 1 big},)
the set of pairs of lattice vectors in the first quadrant spanning a parallelogram of oriented area 1. Then,
(4 displaystylesum_{(x,y) in A} frac{1}{|x|^2 cdot |y|^2 cdot |x+y|^2} = pi.)
Lecture Outline
1. Introduction to Binary Quadratic Forms and Conway’s Topographs
We will begin with the basics of binary quadratic forms and their classification, followed by an introduction to Conway’s topographs—a visual and geometric framework for understanding them.
2. Class Number Formula and Summation over Topographs
Building on the first lecture, we will explore the class number formula and how summation identities arise naturally from the structure of topographs.
3. Evaluation of Lattice Sums via Telescoping over Topographs
The final lecture will focus on telescoping techniques, demonstrating how they can be used to evaluate intricate lattice sums—such as the one above—with geometric meaning.

Zoom link:
https://us02web.zoom.us/j/86186281353?pwd=[REDACTED]

Видеозапис и презентация на първата лекция:

https://youtu.be/z7Pz33JyCuA?si=rQ2L4yXJHMdiDkpe
https://kilin-math.github.io/assets/numbers/telescopic_presentation1.pdf

Семинар по геометрия на МЦМН
2025-04-30 16:00 - 17:30 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
Следващата сбирка на Семинара по геометрия на МЦМН
ще се проведе в сряда, 30 април 2025 г. от 16:00 ч. в зала 403 и онлайн в Zoom:
Доклад на тема
Binary Quadratic Forms and Conway’s Topographs (Lecture 1 of 3)

ще изнесе Nikita Kalinin, Guangdong Technion Israel Institute of Technology.

Следващите две лекции ще бъдат на 07.05.2025 и 14.05.2025 от 16:00 ч.

Abstract: Binary quadratic forms are as elementary as they are mysterious—much like prime numbers. In 1997, John Conway introduced topographs, a powerful geometric tool that provides a geometric visualization of binary quadratic forms and their values. These lectures will explore how topographs, combined with telescoping summation techniques, yield elegant formulas — some with intuitive geometric interpretations. For instance, consider the following result:
Let
(A = big{ (x, y) mid x,yin mathbb{Z}_{geq 0}^2, det(x y) = 1 big},)
the set of pairs of lattice vectors in the first quadrant spanning a parallelogram of oriented area 1. Then,
(4 displaystylesum_{(x,y) in A} frac{1}{|x|^2 cdot |y|^2 cdot |x+y|^2} = pi.)
Lecture Outline
1. Introduction to Binary Quadratic Forms and Conway’s Topographs
We will begin with the basics of binary quadratic forms and their classification, followed by an introduction to Conway’s topographs—a visual and geometric framework for understanding them.
2. Class Number Formula and Summation over Topographs
Building on the first lecture, we will explore the class number formula and how summation identities arise naturally from the structure of topographs.
3. Evaluation of Lattice Sums via Telescoping over Topographs
The final lecture will focus on telescoping techniques, demonstrating how they can be used to evaluate intricate lattice sums—such as the one above—with geometric meaning.

Zoom link:
https://us02web.zoom.us/j/86186281353?pwd=[REDACTED]

Съвместна сбирка на семинара на МЦМН и семинара "Алгебра и Логика"
2025-04-29 14:00 - 15:30 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
Съвместна сбирка на семинара на МЦМН и семинара “Алгебра и Логика” в ИМИ, София, ще се проведе идния вторник, с доклад на Георги Томанов, както следва.

Вторник, 29-ти април, 14:00 часа, зала 403 на ИМИ-БАН.
Георги Томанов, Université Claude Bernard, Lyon 1.
Group action on homogeneous spaces and applications in number theory

Abstract: Many longstanding conjectures and problems in number theory can be reformulated in terms of group actions on homogeneous spaces. This reformulation allows them to be tackled using, alongside deep methods from algebra and algebraic geometry, powerful tools from ergodic theory and dynamical systems. An example of the effectiveness of this approach is Margulis’s groundbreaking proof of the Oppenheim conjecture (formulated in 1929) concerning the values of quadratic forms at integer points.
In this talk, aimed at a general audience, we will describe recent results on the characterization of norm forms—a classical object in algebraic number theory—in terms of their values at integer points. These results answer natural questions and are related to still-open conjectures of Littlewood (from 1930) and of Cassels and Swinnerton-Dyer (from 1955). The proofs rely on studying the actions of maximal tori of algebraic groups on homogeneous spaces of arithmetic origin.

Повече информация можете да намерите на страницата на семинара:
https://icms.bg/category/icms-seminar/

Семинар "Алгебра и логика"
2025-04-25 13:00 - 14:00 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
На 25 април 2025 г. (петък) от 13:00 часа в зала 578 на ИМИ
ще се проведе заседание на семинара по „Алгебра и логика”.
Доклад на тема:
Hilbert scheme of smooth projective curves and some easy examples
ще изнесе
Changho Keem
(Seoul National University, South Korea).
Abstract: Hilbert scheme is a parameter space for a family of projective algebraic varieties sharing a given fixed Hilbert polynomial. In this talk, we will discuss the following topics concerning the Hilbert scheme of smooth projective algebraic curves.
1. Irreducibility problem of the restricted Hilbert scheme of curves.
2. Some easy examples of reducible Hilbert schemes inside or outside the Brill-Noether range.
3. The existence of more than expected dimensional components whose image under the moduli map has small codimension inside the moduli space of curves of genus g.

Поканват се всички желаещи да присъстват.
От секция „Алгебра и логика” на ИМИ – БАН
http://www.math.bas.bg/algebra/seminarAiL/
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Семинар "Математическо моделиране и числен анализ"
2025-04-23 14:00 - 15:30 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
Поредната сбирка на СЕМИНАРА на секция
“Математическо моделиране и числен анализ”
ще се състои на 23.04.2025 г. (сряда) от 14:00 часа в зала 478 на ИМИ – БАН.
Доклад на тема:
Multiscale Leading Edge and Bulk Dynamics for Tumour Invasion in Fibrous Environment
ще изнесе Dr. Dumitru Trucu (University of Dundee, Шотландия).
Резюме: Despite all recent in vivo, in vitro, and in silico advances, the understanding of the genuine biologically multiscale process of solid tumour invasion remains one of the greatest open questions for scientific community. In this talk we present novel mathematical multiscale moving boundary modelling and structural analytical approaches for tumour invasion. Specifically, we focus on characterising mathematically key aspects of the dynamic interactions that the migratory cancer cells population and the accompanying matrix degrading enzymes (MDEs) have with the extracellular matrix (ECM) components, and in particular with the ECM fibres. These are complex interactions enabled by a series of integrated multiscale systems, which are at least two-scale in nature and share (and contribute to) the same tumour macro-dynamics (i.e., tissue-scale dynamics) but have independent-in-nature micro-dynamics (i.e., cell-scale dynamics). For instance, on the bulk of the tumour, of major interest is the dynamics of fibres degradation and structural realignment occurring at micro-scale as well as the immediate impact that this continuously changing field of oriented ECM fibres has over the tumour macro-dynamics. On the other hand, the cell-scale proteolytic micro-dynamics occurring at the tumour invasive edge interacts with the peritumoural ECM fibres through the molecular fluxes of MDEs. This interfacial cell-scale interaction not only results in changes in the micro-scale structural distribution of peritumoural ECM fibres but also influences directly the changes of the overall tumour morphology.
The new mathematical multiscale modelling framework presented here aims to address the precise biological multiscale nature of these interactions between the cancer cell population and the surrounding fibrous environment during solid tumour invasion. This involves an appropriately derived novel 2D & 3D multiscale moving boundary modelling framework as well as state-of-the-art multiscale computational approaches. Furthermore, this research paves the way for new multiscale analysis research avenues that builds on the novel concept of three-scale convergence that I established and introduced a while ago.

Семинар на МЦМН
2025-04-11 16:00 - 17:30 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
Дата: 11.04.2025 г., 16:00 ч.
Място: Зала 403, ИМИ – БАН
Докладчик: Felipe Espreafico Guelerman, Sorbonne Université – Paris
Доклад: On Motivic and Arithmetic Donaldson-Thomas invariants
Допълнителна информация: https://icms.bg/category/icms-seminar/
Резюме. Aiming to understand the relation to other “refined invariants”, and especially their possible interpretation in quantum theory, we explain how to obtain a quadratic, A1-version of Donaldson-Thomas invariants from the motivic refinements first introduced in Kontsevich-Soibelman. Following ideas from Behrend, Bryan and Szendroi, we provide predictions for these invariants in a few simple examples, mainly the computation of DT invariants of A3. Our main goal is to draw relationships with the literature, including works of Levine, Denef and Loser, Azouri, Pepin-Lehaulleur, Srinivas among others. We begin with a brief introduction to A1-enumerative geometry and in the end, we pose some further questions on possible extensions of our definitions. This is joint work with Johannes Walcher. We also comment on joint work in progress with Ran Azouri.

Семинар "Алгебра и логика"
2025-03-28 13:00 - 14:30 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
На 28 март 2025 г. (петък) от 13:00 часа в зала 578 на ИМИ
и онлайн чрез Zoom ще се проведе хибридно заседание на семинара по „Алгебра и логика”.
Доклад на тема:
Graded algebras that are the sum of two homogeneous subalgebras
ще изнесе
Пламен Кошлуков (State University of Campinas, Brazil).
Абстракт. Let A be an algebra over a field F, graded by a group G, and let B and C be two homogeneous subalgebras of A such that A=B+C. We study the following problem: If B and C satisfy graded identities, does the same also hold for A?
The analogous problem for algebras without any grading was proposed in 1994 by Beidar and Mikhalev; in implicit form it appeared in a paper by O. Kegel, in 1963. Several particular cases were considered in a series of papers by various authors. In 2016, Kępczyk gave an affirmative answer to this problem (without grading).
We show that if B and C satisfy graded identities, and also B is a (one-sided) ideal of A then A=B+C also satisfies graded identities. We also study the situation where A satisfies specific graded semi-identities. In this case, if C satisfies some graded identity in neutral variables, we show that A satisfies graded identities. We also find upper bounds for the degrees of such identities. Here we use methods that go back to the classical Regev theorem on the growth of the codimensions of an associative algebra.
Finally we exhibit an example that shows that the graded version of the Kępczyk theorem is no longer valid.
This is a joint work with P. S. Fagundes.

Линк към zoom-стаята на семинара:

Https://us02web.zoom.us/j/85137375021?pwd=[REDACTED]
Поканват се всички желаещи да присъстват.
От секция „Алгебра и логика” на ИМИ – БАН
http://www.math.bas.bg/algebra/seminarAiL/
============================== =====================

Семинар на МЦМН
2025-03-27 16:00 - 17:30 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
Дата: 27.03.2025 г., 16:00 ч.
Място: Зала 403, ИМИ – БАН
Докладчик: Luis Ugarte, University of Zaragoza, Spain
Доклад: Complex structures on Lie algebras and its application to the Hull-Strominger system
Допълнителна информация: https://icms.bg/category/icms-seminar/
Резюме. In this talk we will explain the role that the Lie algebras play in the construction of 6-dimensional compact quotient spaces M=G/Γ, where Γ is a lattice, endowed with an invariant complex structure with holomorphically trivial canonical bundle.We will use the approach of stable forms in six dimensions to provide a classification of unimodular Lie algebras admitting a complex structure with non-zero closed (3,0)-form. Some of these spaces can be equipped with balanced Hermitian metrics and they provide invariant solutions of the Hull-Strominger system, even with non-flat connection on the tangent bundle satisfying the Hermitian-Yang-Mills condition.

Семинар по Приложна математика
2025-03-27 14:00 - 15:30 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
About m-ary Gray codes
Докладчик: д-р Мария Пашинска, ИМИ – БАН
Дата: 27.03.2025 г.
Час: 14:00 ч.
Място: зала 503
Резюме: We present several systemized implementations of the Gray code over an alphabet with m ≥ 2 elements. Gray codes are widely used in digital communications and effective generation of combinatorial objects. We consider two variants – reflected and modular m-ary Gray codes. We present algorithms for their generation and other important functions such as ranking and unranking and functions for generation of a maximal set of non-proportional vectors of length n over the given alphabet. Some applications of the m-ary Gray codes are also considered.
This talk is based on joined work with Stefka Bouyuklieva , Iliya Bouyukliev and Valentin Bakoev.

Семинар на МЦМН
2025-03-25 14:00 - 15:30 | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
Дата: 25.03.2025 г., 14:00 ч.
Място: Зала 403, ИМИ – БАН
Докладчик: Михаил Школников, ИМИ – БАН
Доклад: Affine distance function
Допълнителна информация: https://icms.bg/category/icms-seminar/
Резюме. Affine geometry is sometimes described as “what remains of Euclidean geometry when distances are forgotten”. In this talk, I will report on a very recent discovery of an affine-invariant notion, which may be viewed as a distance from a point inside a convex domain to its boundary. This new concept stems from a suggestion of Conan Leung, who proposed to average the canonical tropical series, a fundamental notion of tropical optics, over the manifold of all tropical structures of fixed covolume on the given affine space. Very little of what we (Nikita Kalinin, Ernesto Lupercio and me) currently know, as well as necessary preliminaries, some observations and precise conjectures, will be covered during the talk, which mainly serves as an invitation to participate in developing this exciting new topic.
