Institute of Mathematics and Informatics

Годишна отчетна сесия на секция "Математическа лингвистика"
2023-12-22 10:00 - 13:00 (Europe/Sofia) | Институт по математика и информатика – БАН, Block 8, 1113 БАН IV км., София, Bulgaria
Годишна отчетна сесия
на секция „Математическа лингвистика“ при ИМИ-БАН
22.12.2023 г., 10:00 ч.
10:00 – 10:15 Иван Держански, Олена Сирук,от
Българските неопределителни местоимения с елемента си и съответствията им в украински език
10:15 – 10:30 Александра Николова,
Интерактивно обучение и сериозни игри
10:30 – 10:45 Иван Крачанов,
Игровизиран краудсорсинг в помощ на семантичната трансформация на дигиталните библиотеки
10:45 – 11:00 Галина Богданова, Тодор Тодоров, Николай Ноев,
Дигитална достъпност за хора със специални потребности: проучвания, концепции и модели
11:00 – 11:15 Евгения Николова,
Стандарти за дигитализация на културно-историческото наследство и тяхната роля в правната сигурност
11:15 – 11:30 Емануела Митрева,
Подходи за персонализация при изучаване на културното наследство
11:30 – 11:45 Десислава Панева-Маринова, Максим Гойнов, Радослав Павлов, Детелин Лучев,
CultIS: софтуерна платформа за интелигентно цифрово управление и представяне на големи масиви от данни и знания от областта на културата, хуманитаристиката и социалните науки – разработка и внедрявания
11:45 – 12:00 Константин Рангочев, Максим Гойнов, Детелин Лучев,
Енциклопедия Slavica Sanctorum – нови наблюдения
12:00 – 12:15 Мария Монова-Желева, Янислав Желев,
Подпомагане на прехода към зелено бъдеще чрез университетски курсове за микроквалификации в областта на Европейски и международни зелени секторни/индустриални стандарти

Отчетна сесия на секция ДУМФ
2023-12-20 14:00 - 15:30
На 20.12.2023г. в зала 478 на ИМИ ще се проведе
ОТЧЕТНА СЕСИЯ
на секция ДУМФ
14:00 – 14:15 Чл.-кор. дфн Стойчо Язаджиев:
Black hole no-hair theorem for self-gravitating time-dependent spherically symmetric multiple scalar fields
14:14 – 14:30 Доц. д-р Тихомир Вълчев
Квазирационални решения на едно интегруемо обобщение на уравнението за феромагнетика на Хайзенберг
14:40 – 14:45 Доц. д-р Александър Стефанов:
New type of dNLS equations related to Kac-Moody algebra A2(1)
14:45 – 15:00 Мат. д-р Милен Иванов:
contact defects / анализ на данни за американските консули 1776-1865
15:00 – 15:15 Доц. д-р Георги Бояджиев:
Пространствено-зависим SEIR модел в епидемиологията.

Годишна отчетна сесия на секция "Изследване на операциите, вероятности и статистика"
2023-12-19 10:00 - 16:00
Годишната отчетна сесия на секция
Изследване на операците, вероятности и статистика
ще се проведе на 19 декември 2023 г. (вторник) от 10:00 ч. в зала 503 на ИМИ-БАН.
ПРОГРАМА
Първа част
10:00 – 10:20 Драгомир Неделчев
Exploiting the gap between real-world and risk-neutral probability measures
10:20 – 10:40 Христо Сариев
Different characterizations of exchangeable measure-valued Pólya urn sequences
10:40 – 11:00 Михаил Кръстанов, Надежда Рибарска
Необходими условия за оптималност, използващи мерки за некомпактност
11:00 – 11:20 Цветелин Заевски
Относно някои композитни Американски опции
11:20 – 11:40 Марусия Божкова, Николай Янев
Многотипни разклоняващи се процеси с нехомогенна имиграция
11:40 – 12:00 Младен Савов
Факторизация на Винер-Хопф
Втора част
13:00 – 13:20 Пенка Майстер, Асен Чорбаджиев
Total progeny of the Negative-Binomial reproduction of particles described by the Wright function
13:20 – 13:40 Цветомир Цачев
Optimal control of COVID-19 spread
13:40 – 14:00 Огнян Кунчев
Приложения на тензорите в съвременния Анализ на данни
14:00 – 14:20 Боян Стефанов
A Sufficient Optimality Condition for a Discrete-Time Optimal Control Problem
14:20 – 14:40 Детелина Камбурова
Long orbit or empty value principle in premetric spaces
14:40 – 15:00 Златогор Минчев
Future of Smart Cities Security Transcendents Modelling & Identification
15:00 – 15:20 Евгения Стоименова
Състоятелност на статистически критерии основани на статистики на превъзхождане
15:20 – 15:40 Николай Китанов
Схеми за усредняване при импулсни управляеми системи

Годишна отчетна сесия на секция ОМИ
2023-12-18 13:00 - 17:00
Годишната отчетна научна сесия на секция
Образование по математика и информатика
ще се проведе на 18 декември 2023 г. от 13:00 ч.
в зала 478 на Института по математика и информатика на БАН.
ПРОГРАМА

Четвърта международна конференция Women in Mathematics in South-Eastern Europe
2023-12-18 09:00 - 2023-12-20 18:00
International Center for Mathematical Sciences – Sofia (ICMS-Sofia)
и
Institute of the Mathematical Sciences of the Americas at the University of Miami (IMSA)
организират
Четвърта международна конференция
Women in Mathematics in
South-Eastern Europe

Една от основните цели, които си поставят организаторите на конференцията, е да създадат нови дългосрочни сътрудничества между учените в Югоизточна Европа. Очаква се със своето участие жените математици да привлекат вниманието на млади изследователи и на изследователи от по-слабо развити страни.
Информация за всички участници, както и заглавия и абстракти на техните доклади, може да намерите тук https://icms.bg/fourth-international-conference-women-in-mathematics-in-south-eastern-europe/

Годишна отчетна сесия на МЦМН
2023-12-15 13:00 - 17:00
Oтчетната сесия на Международния център по математически науки (МЦМН) ще се проведе на 15.12. 2023 г. от 13:00 часа в зала 403 на ИМИ-БАН.

Програма

13:00-13:15 Oleg Mushkarov, Opening remarks
13:15-13:30 Valdemar Tsanov, On nonconvexity of momentum maps
13:30-13:45 Mikhail Shkolnikov, Exact solutions in harmonic sandpile dynamics
13:45–14:00 Break
14:00-14:15 Andrei Bengus-Lasnier, Computing Milчетна чnor numbers with multiplicities for curves
14:15-14:30 Antoni Rangachev, Flat families of curves
14:30-14:45 Jiachang Xu, Aspects of non-Archimedean geometry
14:45-15:00 Break
15:00-15:15 Maryam Bajalan, Polycyclic and multivariable codes over finite rings
15:15-15:30 Hamed Pejhan, Wigner’s elementary systems in de Sitter spacetime and their holographic interpretation
15:30-15:45 Break
15:45–16:00 Yingdi Qin, Atiyah sequence and Connection on Lie groupoid
16:00-16:15 Dimitar Kodjabachev, Picard groups, Galois descent and TMF

Годишна отчетна сесия на секция "Алгебра и логика"
2023-12-15 09:55 - 14:30
Отчетната сесия на секция “Алгебра и логика” за 2023 година
ще се проведе на 15 декември от 9:55 часа в зала 578 на ИМИ-БАН
и онлайн чрез платформата zoom.
Линк към zoom-стаята на сесията:
https://us02web.zoom.us/j/88421224798?pwd=[REDACTED]
ПРОГРАМА
9:55 – 10:00 Opening
10:00 – 10:30 Ivan Chipchakov: Diophantine and cohomological dimensions of fields
10:30 – 10:50 Elitza Hristova: Some new results on the GL(n)-module structure of relatively free algebras and applications to noncommutative invariant theory
10:50 – 11:00 Break
11:00 – 11:30 Hristo Iliev: On the Tschirnhausen module of multiple coverings and some applications
11:30 – 11:50 Veselin Filev: A Sampling Approach for Tackling Large-Scale Linear Optimization Problems
11:50 – 11:55 Break
11:55 – 12:15 Marin Genov: Some Aspects of Holomorphy over Finite-Dimensional Commutative Algebras
12:15 – 12:35 Yacine Barhoumi-Andreani: Max-independence structures in random partitions of an integer
12:35 – 13:30 Lunch Break
13:30 – 13:50 Petar Iliev: There are no Sahlqvist formulae containing at most a logarithmic number of variables that define the n-density or the n-width of Kripke frames
13:50 – 14:10 Tatyana Ivanova: The fragment of elementary plane Euclidean geometry based on perpendicularity alone – a complete axiomatization
14:10 – 14:25 Vilislav Boutchaktchiev: Methods for estimation of the Inferred Loss Given Default of credit portfolios

Годишна отчетна сесия на секция "Математическо моделиране и числен анализ"
2023-12-14 10:00 - 13:00
Годишната отчетна сесия на секция “Математическо моделиране и числен анализ”
ще се проведе на 14.12.2023 – четвъртък, в зала 503 от 10:00 часа.
Посвещава се на паметта на проф. дмн Светослав Марков (1943-2023)

Програма

10:00 -10:20 Михаил Кръстанов, Маргарита Николова, “A sufficient condition for small-time local controllability”
10:20 -10:40 Петър Рашков, Владимира Суванджиева, “Модел на НЕТоза в ранния стадий на Systhemic Lupus Ertyhematosus”
10:40 -11:00 Ирина Георгиева, Clemens Hofreither, “Computation of polynomial and rational approximations in complex domains”
11:00-11:20 Кафе пауза
11:20- 11:40 Евгения Попова, “Chemical reaction networks in terms of proper and directed intervals”
11:40- 12:00 Иван Бажлеков, “Fractional derivatives in the mathematical modelling II.”
12:00- 12:20 Невена Илиева-Литова, “Моделиране на зарядовата зависимост на биологичната активност на линейни антимикробни пептиди”
12:20-12:40 Милен Борисов, Станислав Харизанов, “Application of the Least-Squares Method to semiautomatic orientation of 3D objects”
12:40-13:00 Евгения Сендова, “За Свети с усмивка през сълзи”

Семинар по геометрия на МЦМН
2023-12-13 16:00 - 17:30
Следващата сбирка на Семинара по геометрия на МЦМН
ще се проведе в сряда, 13 декември 2023 г. от 16:00 ч. в зала 403 и онлайн в Zoom:
Доклад на тема

Valuations of Higher Rank
ще изнесе Андрей Бенгуш-Ласние, Международен център по математически науки (МЦМН – София).

Zoom link:

https://us02web.zoom.us/j/83740034721?pwd=[REDACTED]

Семинар по геометрия на МЦМН
2023-12-06 16:00 - 17:30
Следващата сбирка на Семинара по геометрия на МЦМН
ще се проведе в сряда, 6 декември 2023 г. от 16:00 ч. в зала 403 и онлайн в Zoom:
Доклад на тема

Introduction to tropical modifications (II)
ще изнесе Никита Калинин, Международен център по математически науки (МЦМН – София).

Zoom link:

https://us02web.zoom.us/j/83740034721?pwd=[REDACTED]

Национален семинар по стохастика
2023-12-06 14:00 - 15:30
Поредната сбирка на
Националния семинар по стохастика
ще се проведе на 6 декември 2023 г. (сряда) от 14:00 часа в зала 503 на ИМИ – БАН.
Доклад на тема
Brownian Motion Conditioned to Spend Limited Time Outside a Bounded Interval – An Extreme Example of Entropic Repulsion
ще изнесе
Dominic Т. Schickentanz (TU Darmstadt).
Абстракт. We condition a Brownian motion on (mathbb{R}_{ge 0}) on spending a total of at most (s>0) time units outside a bounded interval. We describe the resulting process in terms of an SDE and discuss the surprising result in the context of entropic repulsion. Moreover, we explicitly determine the exact asymptotic behavior of the probability that a Brownian motion on ([0,T]) spends limited time outside a bounded interval, as (Tto infty).
This is joint work with Frank Aurzada (TU Darmstadt) and Martin Kolb (Paderborn Uni)

Семинар на МЦМН
2023-12-05 14:00 - 15:30
Дата: 05.12.2023 г., 14:00 ч.
Място: Зала 403, ИМИ – БАН
Докладчик: Богдан Станков, ИМИ – БАН
Доклад: Recent developments in the study of Følner functions
Допълнителна информация: https://icms.bg/recent-developments-in-the-study-of-folner-functions-talk-by-bogdan-stankov/

Годишна отчетна сесия на секция "Анализ, геометрия и топология"
2023-12-04 13:00 - 16:30
Годишната отчетна сесия на секция „Анализ, геометрия и топология“
ще се проведе на 4 декември (понеделник) от 13:00 ч. в зала 478 на ИМИ-БАН.
ПРОГРАМА

Семинар "Алгебра и логика"
2023-12-01 13:00 - 14:30
На 1 декември 2023 г. (петък) от 13:00 часа ще се проведе хибридно заседание (присъствено в зала 578 на ИМИ-БАН и онлайн чрез платформата zoom) на семинара по „Алгебра и логика”.
Доклад на тема:
Characterization of Ideals of Q-algebras Related to its G-part
ще изнесе
доц. Йорг Копиц, ИМИ – БАН.
Абстракт. In this presentation, we study the (G)-part of (Q)-algebras (X), i.e. the set (G(X)={xin X:0x=x}). We show that (G(X)) is an abelian group, whenever (G(X)) is an ideal and characterize all (Q)-algebras (X) such that (G(X)) is an ideal of (X). Moreover, we show that, up to isomorphism, there is only one (Q)-algebra (X) with (G(X)=X), which is only possible if (|X|=2^{k}) ((kin mathbb{N})).
Линк към Zoom-стаята на семинара:
https://us02web.zoom.us/j/85137375021?pwd=[REDACTED]

От секция „Алгебра и логика” на ИМИ – БАН
http://www.math.bas.bg/algebra/seminarAiL/
============================== =====================

Научен семинар на ВНЗ "Информационно моделиране"
2023-11-28 14:00 - 15:30
На 28 ноември (вторник), от 14 ч., в зала 578 на ИМИ-БАН,
ще се проведе научен семинар на ВНЗ “Информационно моделиране”.
Доклад ще изнесе редовният докторант Светослав Хаджииванов на тема:
Revolutionizing .NET with the Actor Model: The End of Traditional Encapsulation?
Abstract: The actor model is revolutionizing the way we build applications by moving past the traditional idea of encapsulation in object-oriented programming. This model is perfect for today’s computers with multiple CPU cores, where old-school methods fall short, leading to race conditions and other concurrency issues. In this seminar, we’ll introduce you to the basics of this effective approach. Proto.Actor, our toolkit of choice, blends the strength of both new and time-tested practices, making it a solid fit for industries from banking to healthcare. We’ll dig into the actor model’s origins and its capacity for running many tasks smoothly and efficiently, ensuring our systems are reliable even when some parts fail.
За дистанционно включване:
Join Zoom Meeting
https://us02web.zoom.us/j/87619474903?pwd=[REDACTED]
Meeting ID: 876 1947 4903
Passcode: [REDACTED]

Семинар "Математическо моделиране и числен анализ"
2023-11-28 14:00 - 15:30
Семинарът на секция “Математическо моделиране и числен анализ” ще продължи своята работа.
Дата: 28.11.2023 г., 14:00 ч.
Място: Заседателната зала на ИМИ – БАН
Тема: Приложение на математически и статистически модели и методи в областта на мониторинга на горите и земеделските земи с използване на данни от дистанционни изследвания
Докладчици: Проф. д-р Лъчезар Филчев,
гл. ас. д-р Десислава Ганева,
гл. ас. д-р Илина Каменова и
гл. ас. д-р Златомир Димитров
от ИКИТ-БАН
Резюме: Темата изследва как да се използват математически и статистически модели и методи за мониторинг на горите и земеделските земи с данни от дистанционни изследвания. Тя цели да се подобри управлението на екосистемите и хранителната сигурност чрез оценка на рисковете и възможностите, свързани с тези области. Тя има много приложения в областта на картографията, биометрията, агрономията и природозащитата.

Семинар "Алгебра и логика"
2023-11-24 13:00 - 15:00
На 24 ноември 2023 г. (петък) от 13:00 часа ще се проведе дистанционно заседание на семинара по „Алгебра и логика”, на който ще бъдат изнесени два доклада.
От 13:00 ч. Димитринка Владева (ИМИ-БАН) ще изнесе доклад на тема
Catalan numbers and additively idempotent semirings
От 14:00 ч. Русанка Луканова (ИМИ-БАН) ще изнесе доклад на тема
Semantics of Propositional Attitudes in Type-Theory of Algorithms

Заглавие: Catalan numbers and additively idempotent semirings
Абстракт. The purpose of the present talk is to provide new applications of remarkable Catalan numbers. In Richard Stanley’s book Enumerative Combinatorics, Volume II (Cambridge University Press) there are many combinatorial objects that are counted by the Catalan numbers as well as applications in graph theory, Young diagrams, lattice theory, real matrices, real polynomials and so on. We show applications of Catalan numbers in some additively idempotent semirings which appeared in my results in 5 papers published between 2011 and 2023.
The set of nilpotent endomorphisms in the endomorphism semiring of a finite chain is a semiring of order (n – 1)th Catalan number and is an ideal in another semiring of order n th Catalan number. The semiring of k th nilpotent endomorphisms, where 0 ≤ k ≤ n – 1 is of order a product of two Catalan numbers. By complex products of Catalan numbers we describe the roots of arbitrary idempotent of the endomorphism semiring of a finite chain.
In an additively idempotent semiring which is a generalization of the endomorphism semiring of a finite chain considered as a simplex we prove that the subsimplex of nilpotent elements is of order (n – 1) th Catalan number and it is closed under derivations which are projections of the simplex to some simplices.
In the last paper, 2023, we prove that an additively idempotent semiring which is an S0-semialgebra, where S0 is a commutative additively idempotent semiring, and with a finite basis of a special type is isomorphic to a matrix semiring. As a consequence we obtain two different semirings of upper triangular matrices over the Boolean semiring, which are of order (n + 1) th Catalan number.

Заглавие: Semantics of Propositional Attitudes in Type-Theory of Algorithms
Абстракт. Natural language (NL) is notorious for various kinds of ambiguities. Among the most difficult ones, for computational handling of NL, are expressions with multiple occurrences of quantifiers, which contribute to quantifier scope ambiguities. Far more difficult for computational linguistics are NL expressions having occurrences of so-called attitude components designating knowledge, believes, statements, and similar semantic information.
Often, the syntactic complement of an attitude lexeme is a sentential expression. The sentential complement may have subexpressions that designate semantic information belonging to varying scopes. Depending on context, some components can be semantic parts of the attitudinal information, which is in the scope of the propositional attitude, or external to it.
The first formal representation of NL attitudes was by Montague, 1973, along with the quantifier scope ambiguities, by the notions of extension and intension, and using extra-syntactic disambiguation of NL expressions. That approach, while unsatisfactory in important aspects, was adopted and adapted by some variants of Montague grammars, for specific purposes. The problem has been largely open, due to its purely semantic nature and computational difficulties, without direct syntactic appearance.
The semantic phenomena of attitudes include statements in natural language, including in the domains of mathematical texts and proofs.
In this presentation of a recent paper, I extend the type-theory of algorithms, to cover algorithmic semantics of some of the major attitude expressions and their semantic underspecification. I provide reduction calculus for deriving semantic specifications in contexts.

Линк към Zoom-стаята на семинара:
https://us02web.zoom.us/j/85137375021?pwd=[REDACTED]

От секция „Алгебра и логика” на ИМИ – БАН
http://www.math.bas.bg/algebra/seminarAiL/
============================== =====================

Семинар на МЦМН
2023-11-23 14:00 - 15:30
Дата: 23.11.2023 г., 14:00 ч.
Място: Зала 403, ИМИ – БАН
Докладчик: Валдемар Цанов, ИМИ – БАН
Курс: Invariant theory, homogeneous projective varieties, and momentum maps
Резюме: Let (f:Kto U(V)) be a unitary representation of a compact Lie group (K) with Lie algebra (mathfrak k). This series of talks will be devoted to some recent developments based on relations between the following three classical notions.

The ring of -invariant polynomials (mathbb C[V]^K) is finitely generated by homogeneous elements, by a theorem of Hilbert, but the proof is notoriously nonconstructive. The degrees of a minimal set of generators are canonically determined by (f), and will be the focus of the discussion.
The (K)-equivariant momentum map (mu:mathbb P(V)to mathfrak k^*) associated to the Fubini-Study form encodes in its image properties of the invariant ring (mathbb C[V]^K) and the (K)-module structure of the entire polynomial ring (mathbb C[V]), due to theorems of Mumford and Brion. While many general properties of momentum images have been established, explicit descriptions remain unknown in many cases south for in physics and quantum information theory.
Projective geometry of complex (K)-orbits in (mathbb P(V)); their fundamental forms, osculating varieties and secant varieties.

General relations between the first two topics are well established, even in a more general context. There are also well known relations between invariant theory and projective geometry, but secant varieties have only recently been brought to the discussion and are subject of current interest.
After introducing the basic notions, I will derive some properties of momentum images related to fundamental forms and osculating varieties, as well as a lower bound on the minimal positive degree of a homogeneous invariant, derived using secant varieties. At the end I will present a class of homogeneous projective varieties, characterized by a special property of their secant varieties, where the relations between the above three concepts take a particularly pristine form.

Invariant theory, homogeneous projective varieties, and momentum maps, course by Valdemar Tsanov

Семинар по геометрия на МЦМН
2023-11-22 16:00 - 17:30
Следващата сбирка на Семинара по геометрия на МЦМН
ще се проведе в сряда, 22 ноември 2023 г. от 16:00 ч. в зала 403 и онлайн в Zoom:

Topics in non-archimedean analytic geometry (II)

by Jiachang Xu – International Center for Mathematical Sciences (ICMS – Sofia)

Zoom link:

https://us02web.zoom.us/j/83740034721?pwd=[REDACTED]

Семинар на МЦМН
2023-11-21 14:00 - 15:30
Дата: 21.11.2023 г., 14:00 ч.
Място: Зала 403, ИМИ – БАН
Докладчик: Валдемар Цанов, ИМИ – БАН
Курс: Invariant theory, homogeneous projective varieties, and momentum maps
Резюме: Let (f:Kto U(V)) be a unitary representation of a compact Lie group (K) with Lie algebra (mathfrak k). This series of talks will be devoted to some recent developments based on relations between the following three classical notions.

The ring of -invariant polynomials (mathbb C[V]^K) is finitely generated by homogeneous elements, by a theorem of Hilbert, but the proof is notoriously nonconstructive. The degrees of a minimal set of generators are canonically determined by (f), and will be the focus of the discussion.
The (K)-equivariant momentum map (mu:mathbb P(V)to mathfrak k^*) associated to the Fubini-Study form encodes in its image properties of the invariant ring (mathbb C[V]^K) and the (K)-module structure of the entire polynomial ring (mathbb C[V]), due to theorems of Mumford and Brion. While many general properties of momentum images have been established, explicit descriptions remain unknown in many cases south for in physics and quantum information theory.
Projective geometry of complex (K)-orbits in (mathbb P(V)); their fundamental forms, osculating varieties and secant varieties.

General relations between the first two topics are well established, even in a more general context. There are also well known relations between invariant theory and projective geometry, but secant varieties have only recently been brought to the discussion and are subject of current interest.
After introducing the basic notions, I will derive some properties of momentum images related to fundamental forms and osculating varieties, as well as a lower bound on the minimal positive degree of a homogeneous invariant, derived using secant varieties. At the end I will present a class of homogeneous projective varieties, characterized by a special property of their secant varieties, where the relations between the above three concepts take a particularly pristine form.

Invariant theory, homogeneous projective varieties, and momentum maps, course by Valdemar Tsanov

Семинар "Дидактическо моделиране"
2023-11-20 14:30 - 16:00
Поредната сбирка на семинара
Дидактическо моделиране
ще се проведе на 20.11.2023 г. от 14:30 ч. в зала 278 на ИМИ.
Доклад на тема
Точкуване на задачи и използване на скàли при стандартизирани оценявания
ще изнесe
проф. Кирил Банков.

Семинар "Алгебра и логика"
2023-11-17 13:00 - 14:30
На 17 ноември 2023 г. (петък) от 13:00 часа ще се проведе хибридно заседание (присъствено в зала 578 на ИМИ-БАН и онлайн чрез платформата zoom) на семинара по „Алгебра и логика”.
Доклад на тема:
Noncommutative invariants of dihedral groups
ще изнесе
Боян Костадинов, ИМИ – БАН.
Абстракт. We consider the 2-generated free metabelian associative and Lie algebras over the complex field and the invariants of the dihedral groups of finite order acting on these algebras. In the associative case we find a finite set of generators of the algebra of invariants. In the Lie case, when the algebra of invariants is not finitely generated, we give a minimal system of generators of the invariants in the commutator ideal as a module of the algebra of the invariants in the polynomial algebra in two variables. In both associative and Lie cases we compute the Hilbert series of the algebras of invariants.
The results are obtained jointly with Vesselin Drensky.
Линк към Zoom-стаята на семинара:
https://us02web.zoom.us/j/85137375021?pwd=[REDACTED]

От секция „Алгебра и логика” на ИМИ – БАН
http://www.math.bas.bg/algebra/seminarAiL/
============================== =====================

Семинар на МЦМН
2023-11-16 14:00 - 15:30
Дата: 16.11.2023 г., 14:00 ч.
Място: Зала 403, ИМИ – БАН
Докладчик: Валдемар Цанов, ИМИ – БАН
Курс: Invariant theory, homogeneous projective varieties, and momentum maps
Резюме: Let (f:Kto U(V)) be a unitary representation of a compact Lie group (K) with Lie algebra (mathfrak k). This series of talks will be devoted to some recent developments based on relations between the following three classical notions.

The ring of -invariant polynomials (mathbb C[V]^K) is finitely generated by homogeneous elements, by a theorem of Hilbert, but the proof is notoriously nonconstructive. The degrees of a minimal set of generators are canonically determined by (f), and will be the focus of the discussion.
The (K)-equivariant momentum map (mu:mathbb P(V)to mathfrak k^*) associated to the Fubini-Study form encodes in its image properties of the invariant ring (mathbb C[V]^K) and the (K)-module structure of the entire polynomial ring (mathbb C[V]), due to theorems of Mumford and Brion. While many general properties of momentum images have been established, explicit descriptions remain unknown in many cases south for in physics and quantum information theory.
Projective geometry of complex (K)-orbits in (mathbb P(V)); their fundamental forms, osculating varieties and secant varieties.

General relations between the first two topics are well established, even in a more general context. There are also well known relations between invariant theory and projective geometry, but secant varieties have only recently been brought to the discussion and are subject of current interest.
After introducing the basic notions, I will derive some properties of momentum images related to fundamental forms and osculating varieties, as well as a lower bound on the minimal positive degree of a homogeneous invariant, derived using secant varieties. At the end I will present a class of homogeneous projective varieties, characterized by a special property of their secant varieties, where the relations between the above three concepts take a particularly pristine form.

Invariant theory, homogeneous projective varieties, and momentum maps, course by Valdemar Tsanov

Семинар по геометрия на МЦМН
2023-11-15 16:00 - 17:30
Следващата сбирка на Семинара по геометрия на МЦМН
ще се проведе в сряда, 15 ноември 2023 г. от 16:00 ч. в зала 403 и онлайн в Zoom:

Topics in non-archimedean analytic geometry (I),
by Jiachang Xu – International Center for Mathematical Sciences (ICMS – Sofia)

Zoom link:

https://us02web.zoom.us/j/83740034721?pwd=[REDACTED]

Национален колоквиум по математика
2023-11-14 16:15 - 17:30
СЪЮЗ НА МАТЕМАТИЦИТЕ В БЪЛГАРИЯ

ИНСТИТУТ ПО МАТЕМАТИКА И ИНФОРМАТИКА – БАН

НАЦИОНАЛЕН КОЛОКВИУМ ПО МАТЕМАТИКА

​Поредната сбирка на Колоквиума ще се състои на 14 ноември 2023 г. (вторник) от 16:15 часа в Заседателната зала на ИМИ – БАН. Доклад на тема:

Arcs of High Divisibility and Their Applications to Coding Theory
ще изнесе проф. дмн Иван Ланджев,
Институт по матем​атика и информатика, Българска академия на науките.

​Резюме

Семинар по Приложна математика
2023-11-14 14:00 - 15:30
How log-concavity fought lottery frauds in Florida and what it did after winning
Докладчик: Дмитри Карп
Дата: 14.11.2023 г.
Час: 14:00 ч.
Място: Зала 503 на ИМИ-БАН
Резюме: In the talk I will first discuss the log-concavity in parameters of the normalized beta function (which represents the cumulative distribution function of beta distributed random variable) that has been used recently in an investigation of lottery frauds in Florida. I will then present some related properties of incomplete beta function and proceed to general log-concavity problems and their particular cases motivated by various problems in statistics, probability and analysis.
Фейсбук страница на семинара: Семинар по Приложна математика

Семинар на МЦМН
2023-11-14 14:00 - 15:30
Дата: 14.11.2023 г., 14:00 ч.
Място: Зала 403, ИМИ – БАН
Докладчик: Валдемар Цанов, ИМИ – БАН
Курс: Invariant theory, homogeneous projective varieties, and momentum maps
Резюме: Let (f:Kto U(V)) be a unitary representation of a compact Lie group (K) with Lie algebra (mathfrak k). This series of talks will be devoted to some recent developments based on relations between the following three classical notions.

The ring of -invariant polynomials (mathbb C[V]^K) is finitely generated by homogeneous elements, by a theorem of Hilbert, but the proof is notoriously nonconstructive. The degrees of a minimal set of generators are canonically determined by (f), and will be the focus of the discussion.
The (K)-equivariant momentum map (mu:mathbb P(V)to mathfrak k^*) associated to the Fubini-Study form encodes in its image properties of the invariant ring (mathbb C[V]^K) and the (K)-module structure of the entire polynomial ring (mathbb C[V]), due to theorems of Mumford and Brion. While many general properties of momentum images have been established, explicit descriptions remain unknown in many cases south for in physics and quantum information theory.
Projective geometry of complex (K)-orbits in (mathbb P(V)); their fundamental forms, osculating varieties and secant varieties.

General relations between the first two topics are well established, even in a more general context. There are also well known relations between invariant theory and projective geometry, but secant varieties have only recently been brought to the discussion and are subject of current interest.
After introducing the basic notions, I will derive some properties of momentum images related to fundamental forms and osculating varieties, as well as a lower bound on the minimal positive degree of a homogeneous invariant, derived using secant varieties. At the end I will present a class of homogeneous projective varieties, characterized by a special property of their secant varieties, where the relations between the above three concepts take a particularly pristine form.

Invariant theory, homogeneous projective varieties, and momentum maps, course by Valdemar Tsanov

Семинар на секция "Математически основи на информатиката"
2023-11-10 14:00 - 15:30
На 10 ноември 2023 г. (вторник) от 14:00 часа в зала 478 на ИМИ-БАН
ще се проведе заседание на семинара на секция
„Математически основи на информатиката”.
Доклад на тема
On induced (C_4)-free graphs with high average degree
ще изнесе Антонио Жирао.
Абстракт. A long-standing conjecture of Thomassen from the 80’s states that every graph with sufficiently high average degree contains a subgraph with high girth and still preserving large enough average degree. This conjecture has only been resolved in the early 2000’s by Kühn and Osthus in the first non-trivial case i.e. they showed that for every (k), there is (f(k)) such the every graph with average degree at least (f(k)) contains a subgraph which is (C_4)-free with average degree (k).
We will talk about a recent result which strengthens this result of Kühn and Osthus in two ways. First, we prove an analogous induced version and secondly we give much better bounds for the function f allowing us obtain few non-trivial results as simple corollaries. Finally, we use these methods to confirm a conjecture Bonamy et al.
Антонио Жирао e пост-докторант в Оксфордския Университет под ръководството на проф. Алекс Скот. Преди да заеме тази позиция, Антонио работи като пост-докторант в Хайделбергския Университет под ръководството на проф. Феликс Йоос и в Университета в Бирмингам под ръководството на проф. Даниела Кюн и проф. Дерек Остюс. Защитава докторантурата в Университета в Кеймбридж под ръководството на проф. Бела Болобаш през 2018 г.

Семинар "Алгебра и логика"
2023-11-10 13:00 - 14:30
На 10 ноември 2023 г. (петък) от 13:00 часа ще се проведе хибридно заседание (присъствено в зала 578 на ИМИ-БАН и онлайн чрез платформата zoom) на семинара по „Алгебра и логика”.
Доклад на тема:
Transfinite version of the Mittag-Leffler condition for the vanishing of the derived limit
ще изнесе
Mishel Carelli (Technion – Israel Institute of Technology, Israel).
Абстракт. We give a necessary and sufficient condition for an inverse sequence S0 ← S1 ← . . . indexed by natural numbers to have lim¹S = 0. This condition can be treated as a transfinite version of the Mittag-Leffler condition. We consider inverse sequences in the category of abelian groups. We also show that the class of inverse sequences S such that lim S = lim¹S = 0 is the least class of inverse sequences containing the trivial inverse sequence and closed with respect to small limits and a certain type of extensions.
Линк към Zoom-стаята на семинара:
https://us02web.zoom.us/j/85137375021?pwd=[REDACTED]

От секция „Алгебра и логика” на ИМИ – БАН
http://www.math.bas.bg/algebra/seminarAiL/
============================== =====================

Семинар по геометрия на МЦМН
2023-11-08 16:00 - 17:30
Следващото заседание на семинара по геометрия на МЦМН ще се проведе на
8 ноември 2023 г., сряда, от 16:00 ч. в зала 403 и онлайн. Доклад на тема
Tropicalizations II
ще изнесе Михаил Школников, ИМИ – БАН.
Абстракт: I will start by briefly recalling the two approaches to tropicalizing subvarieties of algebraic tori. We then transition to the compactified version, substituting the torus with a toric variety, and formalizing the concept of embedded tropical varieties together with a notion of their smoothness. Notably, not all such varieties can be realized as tropicalizations of classical varieties, and different embeddings of classical varieties yield combinatorially distinct tropicalizations, which we equate through so-called modifications. We will conclude by addressing the question of recovering information about classical varieties from their tropicalizations, exemplified by the phase tropical limit having the same topology as corresponding complex hypersurfaces provided that the usual tropicalization is smooth.

Tropicalizations II, a talk by M. Shkolnikov

Zoom link:
https://us02web.zoom.us/j/83740034721?pwd=[REDACTED]
