На 31 октомври 2023 г. (вторник) от 16:00 часа в зала 578 на ИМИ-БАН ще се проведе заседание на семинара на секция „Математически основи на информатиката". Доклад ще изнесе д-р Константин Воробьов (ИМИ - БАН). Абстракт. In this work, we consider the problem of determining the exact value of A_2(n, {d, d+2}) defined as the maximal cardinality of a binary code of length n with two possible distances d and d+2 . We prove that for fixed even d and n big enough, an optimal code must be a constant-weight code of weight d/2+1 with possibly no more than one additional codeword of a different weight. We also find exact values A_2(n, {4, 6}) and A_2(n, {6, 8}) [...]

Дата: 02.11.2023 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: Петър Далаков, ИМИ - БАН Курс: Introduction to Projective Structures and Opers Резюме: A complex projective structure on a Riemann surface is determined by an atlas, whose transition functions are Moebius (fractional-linear) transformations. There are multiple   descriptions of these structures: as certain flat PGL_2-bundles, as Sturm-Liouville operators, as holomorphic connections on the (first) jet bundle of the dual of a theta-characteristic, etc. This mini-course is an introduction to the fundamentals of projective structures, accessible to students and non-specialists. We will also explore links to some classical geometric objects (such as quadratic differentials and Schwarzian derivatives), as well as some generalisations (G-opers) introduced by Beilinson and Drinfeld. https://icms.bg/introduction-to-projective-structures-and-opers/    

На 3 ноември 2023 г. (петък) от 13:00 часа ще се проведе дистанционно заседание на семинара по „Алгебра и логика”. Доклад на тема: A Reduction of Temporary Coalitions in Infinite Multiplayer Games ще изнесе Димитър Гелев. Абстракт. We propose a transformation of Concurrent Game Models which enables the reduction of infinite multiplayer games where players can form temporary coalitions to games with no coalitions by extending moves to include the negotiation steps that lead to the formation of coalitions. We adopt conditional promises as the building blocks of negotiation. Temporary coalitions and their agendas arise as the logical consequences of mutual promises. The transformation enables the use of established solution concepts about games with no coalitions for the analysis of games with temporary coalitions. [...]

Дата: 06.11.2023 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: Петър Далаков, ИМИ - БАН Курс: Introduction to Projective Structures and Opers Резюме: A complex projective structure on a Riemann surface is determined by an atlas, whose transition functions are Moebius (fractional-linear) transformations. There are multiple   descriptions of these structures: as certain flat PGL_2-bundles, as Sturm-Liouville operators, as holomorphic connections on the (first) jet bundle of the dual of a theta-characteristic, etc. This mini-course is an introduction to the fundamentals of projective structures, accessible to students and non-specialists. We will also explore links to some classical geometric objects (such as quadratic differentials and Schwarzian derivatives), as well as some generalisations (G-opers) introduced by Beilinson and Drinfeld. https://icms.bg/introduction-to-projective-structures-and-opers/    

Поредното заседание на Общия семинар на секция "Анализ, геометрия и топология" ще се проведе на 7 ноември 2023 г. от 14:00 часа в зала 478 на ИМИ - БАН. Доклад на тема: New and little known properties of the Fox and Fox-Wright functions ще изнесе Dmitrii Karp, Holon Institute of Technology, Holon, Israel. Поканват се всички интересуващи се. Резюме. In the talk, I will introduce the functions H of Fox and W of Wright (its general case known as Fox-Wright function) and some motivation behind them. Then, I will discuss the extension of Gauss' expansion and summation formulas for the hypergeometric function to the case of general Fox-Wright function and Norlund's expansion for the Meijer's G function to the case of Fox's H function. [...]

Поредната сбирка на Националния семинар по стохастика ще се проведе на 8 ноември 2023 г. (сряда) от 14:00 часа в зала 503 на ИМИ - БАН. Доклад на тема Hamiltonicity of randomly perturbed graphs ще изнесе Alberto Espuny Díaz (Postdoctoral researcher at Universität Heidelberg, Germany). Абстракт: In parallel to the development of smoothed analysis of algorithms, the study of randomly perturbed graphs has thrived in the combinatorics community. The setup is the following: one considers a dense graph $H$ which fails to satisfy some increasing property and then sprinkles edges randomly until the property appears. A main goal in the area is to understand how many random edges are needed, and which graphs $H$ are "worst" for this problem. In this talk I will survey [...]

Поредната сбирка на Националния семинар по стохастика ще се проведе на 15 ноември 2023 г. (сряда) от 14:00 часа в зала 503 на ИМИ - БАН. Доклад на тема Anti-concentration of Rademacher sums and Tomaszewski's counterpart problem ще изнесе Julien Portier, University of Cambridge. Абстракт  

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 [...]

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 = [...]

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 [...]

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:K\to 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 K -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 [...]

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

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

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=VnBtcVpGUktscHQ4a09jZkNZTURyZz09

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:K\to 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 K -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 [...]

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 [...]

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.

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:K\to 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 K -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 [...]

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=VnBtcVpGUktscHQ4a09jZkNZTURyZz09

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:K\to 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 K -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 [...]

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. [...]

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, [...]

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. [...]

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)=\{x\in 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 [...]

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/

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, [...]

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=VnBtcVpGUktscHQ4a09jZkNZTURyZz09

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=VnBtcVpGUktscHQ4a09jZkNZTURyZz09

На 8 януари 2024 г. (понеделник) от 13:00 часа в зала 578 на ИМИ-БАН и онлайн чрез платформата zoom ще се проведе хибридно заседание на семинара по „Алгебра и логика”. Доклад на тема: On the exceptional series and its siblings ще изнесе Bruce Westbury (retired from University of Warwick, UK). Абстракт. The exceptional series is the following series of eight simple Lie algebras: A1, A2, G2, D4, F4, E6, E7, E8 Consider each Lie algebra, g, as a representation of the group Aut(g). Then the centraliser algebras of the first five tensor powers of g have common structure. First, they have the same branching rules. We introduce a parameter so that the exceptional series is a set of eight points on a line. Then the [...]

Дата: 09.01.2024 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: д-р Антони Рангачев, ИМИ - БАН Доклад: Stratified Morse theory and the critical locus of a linear functional Допълнителна информация: https://icms.bg/stratified-morse-theory-and-the-critical-locus-of-a-linear-functional-talk-by-antony-rangachev/ Резюме. In this talk I will use stratified Morse theory to relate the number of critical points of a generic linear functional on a complex analytic manifold M to the Euler characteristics of M and a generic hyperplane slice of M.

Дата: 11.01.2024 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: д-р Антони Рангачев, ИМИ - БАН Доклад: The Milnor number of a smoothable curve Допълнителна информация: https://icms.bg/the-milnor-number-of-a-smoothable-curve-talk-by-antony-rangachev/ Резюме. In this talk I will derive an algebraic formula for the Milnor number of a smoothable complex analytic curve singularity X by relating it to the Euler characteristic of its smoothing, which in turn I will relate to the multiplicity of the Jacobian ideal of X and and the multiplicity of X at its singular point. If time permits I will discuss generalizations to higher dimensions. This is a report on a joint work with Gaffney and Bengus-Lasnier.  

Поредната сбирка на семинара Дидактическо моделиране ще се проведе на 15.01.2024 г. от 14:30 ч. в зала 278 на ИМИ. Доклад на тема Методиката на Бхаскара "Гледай!" ще изнесe проф. Иван Тонов.

Дата: 16.01.2024 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: Carlos Varea (Universidade Tecnológica  Federal do Paraná - Campus Cornélio Procópio, Brazil) Доклад: The H-flux on flag manifolds generated by infinitesimal T-duality Допълнителна информация: https://icms.bg/the-h-flux-on-flag-manifolds-generated-by-infinitesimal-t-duality-talk-by-carlos-varea/ Резюме. In this talk we present a new correspondence for pairs (\mathbb{F},H) formed by a flag manifold \mathbb{F} together with an $H$-flux on \mathbb{F} . Given its role within our correspondence, infinitesimal T -duality may be viewed as a source of H -flux, in the sense that it contributes towards taking fluxless pairs (\mathbb{F},0) to pairs (\mathbb{F}^\vee, H^\vee) carrying nontrivial flux H^\vee\neq 0 . We also illustrate how our correspondence exchanges complex structures with symplectic ones up to B -transformations. This is a joint [...]

Сбирка на семинара "Математически основи на информатиката" ще се проведе във Велико Търново на 17 януари (сряда) от 16 часа в зала 502 на ФМИ - ВТУ. Доклад на тема Build your own digital device, even a multicore and multithreaded  icrocontroller with FPGA ще изнесе Душан Биков, Университет „Гоце Делчев“ – Щип. Резюме: The use of Field-Programmable Gate Arrays (FPGAs) plays an essential role in providing flexibility for digital design. We then delve into practical insights on utilizing and constructing Intellectual Property (IP) cores within the FPGA framework. In addition to this, a new type of multithreaded and multicore microcontroller will be presented. The aim is to provide more computing power for embedded applications. Through parallelism, the microcontroller can run multiple tasks, either independently [...]

На 18 януари 2024 г. (четвъртък) от 13:00 часа в зала 403 на ИМИ-БАН и онлайн чрез платформата zoom ще се проведе съвместно заседание на Семинара на секция „Алгебра и логика” и Семинара на Международния център по математически науки към ИМИ-БАН. Доклад на тема Nilpotent algebras, groups and beyond ще изнесе Yuri Bahturin (Memorial University of Newfoundland, Canada) (joint work with Alexander Olshanskii). Абстракт: We study various correspondences between finite-dimensional nilpotent algebras and (quasi)groups similar to those given by the circle product in the case of associative algebras or by the Baker-Campbell-Hausdorff formulas in the the case of Lie algebras or their generalizations. In the particular case of Malcev's correspondence, we obtain some new results about groups using Lie algebras and vice versa. Линк към [...]

Поредното заседание на Общия семинар на секция "Анализ, геометрия и топология" ще се проведе на 23 януари 2024 г. от 14:00 часа в зала 478 на ИМИ - БАН. Доклад на тема: Complex Dirac structures on flag manifolds ще изнесе Carlos Augusto Bassani Varea, Universidade Tecnológica Federal do Paraná, Brazil. Поканват се всички интересуващи се. Резюме. In this talk we present a description of the invariant complex Dirac structures with constant real index on a maximal flag manifold in terms of the roots of the Lie algebra which defines the flag manifold. As a particular case, when the real index is zero, we have the description of all invariant generalized complex structures on a maximal flag manifold. We also present a classification of the [...]

Поредната сбирка на Националния семинар по стохастика ще се проведе на 24 януари 2024 г. (сряда) от 14:00 часа в зала 503 на ИМИ - БАН. Доклад на тема Wave field source localization using antenna arrays as a statistical problem of multidimensional linear system parameter estimation ще изнесе Alexander Varypaev (Национален институт по геофизика, геодезия и география, БАН). Абстракт. The problem of statistical estimation of the coordinates of wave field sources from observations masked by additive random noise is considered. A likelihood-based estimate of source parameters is proposed for an unknown deterministic source function and additive noise correlated in time and space. The property of this estimate to suppress spatially correlated noise is mathematically justified. A statistical justification for the currently popular and robust [...]

Следващата сбирка на Семинара по геометрия на МЦМН ще се проведе в сряда, 24 януари 2024 г. от 16:00 ч. в зала 403 и онлайн в Zoom: Доклад на тема Introduction to Derived Algebraic Geometry and deformation theory ще изнесе Инди Чин, ИМИ - БАН. Zoom link: https://us02web.zoom.us/j/83740034721?pwd=VnBtcVpGUktscHQ4a09jZkNZTURyZz09

Поредната сбирка на семинара Дидактическо моделиране ще се проведе на 29.01.2024 г. от 14:30 ч. в зала 278 на ИМИ. Доклад на тема Любопитно за конструирането на „вечни календари“ ще изнесe доц. Валентин Христов.

Дата: 30.01.2024 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: Владимир Митанкин, ИМИ - БАН Доклад: Density of Hasse failures for diagonal affine cubic surfaces Допълнителна информация: https://icms.bg/density-of-hasse-failures-for-diagonal-affine-cubic-surfaces-a-talk-by-vladimir-mitankin/ Резюме. А question of Mordell asks which integers are the sum of three cubes provided that there are no local obstructions to that. While Mordell’s question seems out of reach with the current machinery, it is widely believed that every integer not congruent to 4 or 5 mod 9 is a sum of three integral cubes. If, instead of the sum of three cubes, a general ternary cubic is considered, local conditions no longer suffice for solubility, i.e. the integral Hasse principle may fail. In this talk we shall apply the integral version of the [...]

Temporal networks, Tensors, and applications to ML Докладчик: проф. Огнян Кунчев, ИМИ - БАН Дата: 31.01.2024 г. Час: 15:00 ч. Място: ... Резюме: Recently, temporal networks got an increasing interest, related to their numerous applications in real-life data analysis. The temporal networks (more mathematically, “graphs depending on time”) are a typical example of a Tensor – the adjacency matrix depends on several parameters and is a tensor (in the mathematical sense of the word). We present some recent results about the structure of the spectrum of the normalized Laplacian in the case of “slowly varying temporal networks”. The detailed structure of the spectrum gives rise of the notion of “constant block Jacobi model”, which has closed-form solution for the spectrum and the eigenfunctions. This [...]

Следващата сбирка на Семинара по геометрия на МЦМН ще се проведе в сряда, 31 януари 2024 г. от 16:00 ч. в зала 403 и онлайн в Zoom: Доклад на тема Derived Deformation Theory and Formal Moduli Problem ще изнесе Инди Чин, МЦМН и ИМИ - БАН. Zoom link: https://us02web.zoom.us/j/83740034721?pwd=VnBtcVpGUktscHQ4a09jZkNZTURyZz09 Abstract: Derived deformation theory studies the formal neighborhoods of moduli spaces. The classical work of Kodaira-Spencer on deformation of complex manifolds tells that the dg Lie algebra A^(0,*)(X,TX) controls the deformations of the complex manifold. The example illustrates the following general principle: A dg Lie algebra gives rise to a deformation functor by considering the  Maurer-Cartan elements of the dg Lie algebra tensoring with the maximal ideal of an Artin local ring. This idea is explored by [...]

Дата: 06.02.2024 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: Paul Horja, University of Miami, USA Доклад: A categorical view of singularity theory I Допълнителна информация: https://icms.bg/a-categorical-view-of-singularity-theory-i-and-ii-talks-by-paul-horja/ Резюме. The mirror symmetry phenomenon was discovered by string theorists more than thirty years ago as an equivalence of two physical theories associated with very different geometries. The categorical point of view on this remarkable conjecture was famously introduced by M. Kontsevich in his 1994 ICM talk. As it became clear over time, homological mirror symmetry provides new approaches to many topics in symplectic and algebraic geometry. In these two talks, I will present a brief overview of the conjecture as well as some results inspired by mirror symmetry and obtained in joint work with [...]

Следващата сбирка на Семинара по геометрия на МЦМН ще се проведе в сряда, 7 февруари 2024 г. от 16:00 ч. в зала 403 и онлайн в Zoom: Доклад на тема Introduction to curve counting ще изнесе Михаил Школников, ИМИ - БАН. Zoom link: https://us02web.zoom.us/j/83740034721?pwd=VnBtcVpGUktscHQ4a09jZkNZTURyZz09 Abstract: This talk is intended as a very gentle introduction to the classical subject of enumerative geometry concerned with problems of counting algebraic curves with prescribed properties. In the realm of classical planimetry, we know that there exists a single circle passing through a collection of three points, provided that these points are generic. Here “generic” simply means that the points are not collinear, i.e. don’t belong to the same line but could refer to some other open condition in [...]

Дата: 08.02.2024 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: Paul Horja, University of Miami, USA Доклад: A categorical view of singularity theory II Допълнителна информация: https://icms.bg/a-categorical-view-of-singularity-theory-i-and-ii-talks-by-paul-horja/ Резюме. The mirror symmetry phenomenon was discovered by string theorists more than thirty years ago as an equivalence of two physical theories associated with very different geometries. The categorical point of view on this remarkable conjecture was famously introduced by M. Kontsevich in his 1994 ICM talk. As it became clear over time, homological mirror symmetry provides new approaches to many topics in symplectic and algebraic geometry. In these two talks, I will present a brief overview of the conjecture as well as some results inspired by mirror symmetry and obtained in joint work with [...]

На 8 февруари 2024 г. (четвъртък) от 15:00 часа в зала 256 на ИМИ-БАН ще се проведе заседание на семинара на секция „Математически основи на информатиката". Доклад на тема  Extremal problems in Euclidean combinatorial geometry ще изнесе доц. д-р Данила Черкашин Абстракт.  I will talk about several problems in the intersection of extremal combinatorics and Euclidean geometry. Recent results on the Steiner tree problem, Gilbert-Steiner problem, and Nelson-Hadwiger problem will be presented. Семинарът може да бъде проследен и на https://meet.jit.si/IMI-MOI-14400

Дата: 13.02.2024 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: Jean-Pierre Gazeau (APC, Université Paris - Cité) Доклад: Quantum circuit complexity for light polarisation or complexity with no complex numbers Допълнителна информация: https://icms.bg/quantum-circuit-complexity-for-light-polarisation-or-complexity-with-no-complex-number-talk-by-jean-pierre-gazeau/ Резюме. I will present a form of quantum circuit complexity that extends to open systems. To illustrate the methodology, I focus on a basic model where the Hilbert space of states is represented by the Euclidean plane. Specifically, the investigation is about the dynamics of mixed quantum states as they undergo interactions with a sequence of gates. The approach involves the analysis of sequences of density matrices. Each density matrix evolves within the framework of a Gorini-Kossakowski-Lindblad-Sudarshan (GKLS) process during the time interval between consecutive gates. Notably, when considering [...]

Поредната сбирка на Националния семинар по стохастика ще се проведе на 14 февруари 2024 г. (сряда) от 14:00 часа в зала 503 на ИМИ - БАН. Доклад на тема Computable inference for generalised Wright-Fisher processes ще изнесе Nathan Judd (University of Warwick, UK). Абстракт.In this talk, we will introduce a class of [0,1]-valued Markov processes with jumps that, as signals in hidden Markov models, admits a computable (exact) filter. By computable filter we mean that each filtering distribution, i.e., the law of the signal at a time t given the data up to time t, is explicitly and exactly available as a finite mixture of Dirichlet distributions. We exploit the tractability of the Wright-Fisher diffusion, in particular, its infinite-sum transition function and its dual process, [...]

Следващата сбирка на Семинара по геометрия на МЦМН ще се проведе в сряда, 14 февруари 2024 г. от 16:00 ч. в зала 403 и онлайн в Zoom: Доклад на тема Refined curve counting ще изнесе Михаил Школников, ИМИ - БАН. Zoom link: https://us02web.zoom.us/j/83740034721?pwd=VnBtcVpGUktscHQ4a09jZkNZTURyZz09 Abstract: Refining an enumerative problem upgrades the numerical solution to a polynomial so that its specialization gives the original number. A prototypical example of such refinement arises in the tropical curve counting from replacing Mikhalkin multiplicities, corresponding to counting complex curves, with Block-Goettsche multiplicities. I will speak about the invariance of this count and its various interpretations.

На 22 февруари (четвъртък), от 14 ч., в зала 503 на ИМИ-БАН, ще се проведе научен семинар на ВНЗ "Информационно моделиране". Доклад на тема: Интегриране на релационни данни и неструктурирани големи данни с подобен на SQL функционален език ще изнесе гл. ас. д-р Боян Колев. Резюме: Polystore systems have been proposed to provide integrated access to multiple, heterogeneous data stores through a single query engine. In particular, much attention is being paid on the integration of relational data with unstructured big data typically stored in HDFS. One typical legacy solution is to use a relational query engine that allows SQL-like queries to retrieve data from HDFS, which requires the system to provide a relational view of the unstructured data and hence is not always [...]

На 23 февруари 2024 г. (петък) от 13:00 часа ще се проведе дистанционно заседание на семинара по „Алгебра и логика”. Доклад на тема: Invariant subalgebras of the rational Cherednik algebra ще изнесе Niall Hird (University of Glasgow, UK). Абстракт. The rational Cherednik algebra is a degeneration of the double affine Hecke algebra and an object of interest to many representation theorists, it also has strong connections to integrable systems. In my talk I will discuss two subalgebras that arise from considering the invariants of the action of reductive subgroups of the special linear group. In particular we will examine the centres of these invariant subalgebras and compare with the algebra of invariants of the centre of the entire rational Cherednik algebra under the same [...]

Следващата сбирка на Семинара по геометрия на МЦМН ще се проведе в сряда, 28 февруари 2024 г. от 16:00 ч. в зала 403 и онлайн в Zoom: Доклад на тема Linear embeddings of complex Grassmannians ще изнесе Иван Пенков, Constructor University Bremen. Zoom link: https://us02web.zoom.us/j/83740034721?pwd=VnBtcVpGUktscHQ4a09jZkNZTURyZz09 Abstract: A linear embedding of Grassmannians, one of which could possibly be isotropic, is an embedding which respects the generators of Picard groups. Several years ago A.S. Tikhomirov and I classified such embeddings when both Grassmannians are simultaneously usual Grassmannians or isotropic Grassmannians of the same type(orthogonal or symplectic). In this talk I will discuss also the mixed case. A classification as above has an application to the classification of infinite-dimensional linear ind-Grassmannians, and I shall  briefly explain this [...]

Дата: 12.03.2024 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: Morgan Brown  (University of Miami) Доклад: The Cox ring perspective on birational geometry Допълнителна информация: https://icms.bg/the-cox-ring-perspective-in-birational-geometry-talk-by-morgan-brown/ Резюме. The Mori program for birational classification of algebraic varieties attempts to classify algebraic varieties by producing canonical models, polarized by the canonical class. This is accomplished through a series of algebraic surgery operations, such as flips, flops, and divisorial contractions. A complementary viewpoint is that of the total coordinate ring or Cox ring. Here birational maps are understood by looking at the totality of all linear series on the variety, endowed with a ring structure directly analogous to that of the homogeneous coordinate ring of a projective variety. I will give an overview of how [...]

Дата: 14.03.2024 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: Morgan Brown  (University of Miami) Доклад: Cox rings and characterization of toric varieties Допълнителна информация: https://icms.bg/the-cox-ring-perspective-in-birational-geometry-talk-by-morgan-brown/ Резюме. Recently Moraga and Svaldi proved a conjecture of Shokoruv, characterizing in the relative case toroidal morphisms as those which admit divisors with many components relative to the Picard rank. I will discuss the global version, proved in previous joint work with McKernan, Svaldi and Zong. The proof relies on characterizing the singularity type of the Cox ring, giving another example of the use of these invariants in birational geometry.

Сбирка на семинара "Математически основи на информатиката" ще се проведе във Велико Търново на 18 март (понеделник) от 16:30 часа в зала 401 на корпус 4 на ВТУ. Доклад на тема LCD Codes over Mixed Alphabets ще изнесе Maryam Bajalan, ИМИ - БАН. Резюме: In this presentation, we describe the structural properties of (Galois) linear complementary dual codes over mixed alphabets arising from finite chain rings. Our focus centres on providing a comprehensive characterization, outlining the conditions under which a given code falls into this category and it is Galois invariant. This leads to the study of the Gray image of FpFp[θ]-linear codes, where p ∈ {2,3} and θ ≠ θ2 = 0 , that provides Fp-linear complementary dual codes. Join Zoom Meeting https://us05web.zoom.us/j/87139062405?pwd=OytyS4AVwUy9U0Ok9hbW9tivGfFauR.1 [...]

Дата и час: 19.03.2024 г., сряда, 16:00 ч. Място: изцяло в Zoom Лектор: Веселин Петков (Université Bordeaux) Доклад: Dynamical zeta function for billiard flow Абстракт: We will present briefly the connection between Riemann zeta function, Ruellle zeta function and dynamical zeta function. The last one is related to the billiard flow for the union D \subset R^d of a finite collection of pairwise disjoint strictly convex compact obstacles. Let \mu_j \in C , \Im \mu_j > 0 be the resonances of the Laplacian in the exterior of D with Neumann or Dirichlet boundary condition on \partial D . For d odd, u(t) = \sum_j e^{i |t| \mu_j} is a distribution in \mathcal{D}'(R \setminus \{0\}) and the Laplace [...]

Следващата сбирка на Семинара по геометрия на МЦМН ще се проведе в сряда, 20 март 2024 г. от 16:00 ч. в зала 403: Доклад на тема Ellipsoid superpotentials: obstructing symplectic embeddings by singular algebraic curves ще изнесе Григори Михалкин, Женевски университет. Abstract: How singular can be a local branch of a plane algebraic curve of a given degree d? A remarkable series of real algebraic curves was constructed by Stepan Orevkov. It is based on even-indexed numbers in the Fibonacci series: a degree 5 curve with a 13/2 cusp, a degree 13 curve with a 34/5-cusp, and so on. We discuss this and other series of algebraic curves in the context of the problem of symplectic packing of an ellipsoid into a ball, with [...]

На 22 март 2024 г. (петък) от 13:00 часа ще се проведе дистанционно заседание на семинара по „Алгебра и логика”. Доклад на тема: On the uniqueness of maximal solvable extensions of nilpotent Lie algebras ще изнесе Bakhrom A. Omirov (Harbin Institute of Technologies, Harbin, China and Romanovskiy Institute of Mathematics, Uzbekistan Academy of Sciences, Uzbekistan). Абстракт. During the talk it will be shown that under certain condition an arbitrary complex finite-dimensional maximal extension of a nilpotent Lie algebra N is isomorphic to the semidirect sum of N and its maximal torus. A criterion of the completeness for a finite-dimensional solvable Lie algebra is established. Comparisons with some existing results will also be discussed. Линк към Zoom-стаята на семинара: https://us02web.zoom.us/j/85137375021?pwd=RE5QczdFTE1xL1R6MnI2b1lkcGczQT09 От секция „Алгебра и логика” на [...]

On constructions of spherical codes Докладчик: д-р Константин Воробьов, ИМИ - БАН Дата: 27.03.2024 г. Час: 16:00 ч. Място: зала 503 Резюме: In this talk, we review various approaches to construct spherical codes with a given coding distance. We also propose a new approach that allows us to find new codes on spheres in small dimensions. In particular, we find a previously unknown kissing arrangement of 40 spheres in R^5.  

Следващата сбирка на Семинара по геометрия на МЦМН ще се проведе в сряда, 27 март 2024 г. от 16:00 ч. в зала 403: Доклад на тема Reading seminar of geometric Lubin-Tate theory ще изнесе Jiachang Xu, ИМИ - БАН. Abstract: This is reading seminar of geometry of Lubin-Tate theory, our goal is to understand the papers “M. J. Hopkins and B. H. Gross, Equivariant vector bundles on the Lubin-Tate moduli space” and “Ramero, Lorenzo On a class of étale analytic sheaves”. The first seminar we plan to go over the basis of deformation theory, formal group and necessary rigid geometry. Zoom link: https://us02web.zoom.us/j/83740034721?pwd=VnBtcVpGUktscHQ4a09jZkNZTURyZz09

На 29 март 2024 г. (петък) от 13:00 часа ще се проведе дистанционно заседание на семинара по „Алгебра и логика”. Доклад на тема: Generalized Definability of Discrete Time Interval-based Temporal Connectives ще изнесе Димитър Гелев, ИМИ - БАН. Абстракт. In Linear Temporal Logic with past (PLTL), expressive completeness implies that any first-order definable connective is also definable in the temporal language based on the Since and Until temporal operators. This is not the case about discrete time interval-based temporal logics with state-based semantics for the propositional variables. In this talk I prove the next best thing about the extension ITLNL of Moszkowski's discrete time propositional Interval Temporal Logic (ITL) by the neighbourhood modalities: given an interval-based connective # which admits a first-order definition, a star-free ITLNL defining formula for #(A1,...,Am) can be produced that [...]

На 10.04.2024 г. от 14:15 в зала 478 на ИМИ ще се състои поредната сбирка на семинара по Диференциални уравнения и математическа физика. Доклад на тема CHEMICAL COMPOSITION OF THE SUN DISK AND OF THE STARS’ DISKS. EVOLUTION OF THE STARS. BINARY SYSTEMS. GEOMAGNETIC STORMS. SATELLITES. SOLAR-TERRESTIAL INVESTIGATION AND SOLAR WIND. AIRPLANES AND HELICOPTERS ще изнесе Емилиан Атанасов. Всички интересуващи се са добре дошли

На 12 април 2024 г. (петък) от 13:00 часа ще се проведе дистанционно заседание на семинара по „Алгебра и логика”. Доклад на тема: On an Aspect of Second Quantum Revolution ще изнесе Валентин Илиев, ИМИ - БАН. Абстракт. The 2022 Nobel Prize in Physics has been awarded to Alain Aspect, John Clauser, and Anton Zeilinger for their work in Quantum Theory. Mass media called this event part of second quantum revolution which includes mainly quantum computing and other super-technologies. Here we discuss Alain Aspect's version of Einstein-Podolsky-Rosen thought experiment and show that there exists an internal dependence of the simultaneous measurements made by the two pairs of linear polarizers operated in each leg of the apparatus during this experiment. The corresponding Shannon-Kolmogorov information flow [...]

Поредната сбирка на Националния семинар по стохастика ще се проведе на 16 април 2024 г. (сряда) от 14:00 часа в зала 503 на ИМИ - БАН. Доклад на тема Convergence Rate for Order 1 Markov Random Walks ще изнесе Петър Гайдаров. Абстракт. We examine the limiting behaviour of an order 1 Markov random walk in R2, i.e. a walk that remembers its previous step. Provided a certain symmetry of the Markovian condition, under relatively mild conditions we prove convergence to a Brownian motion and bound the rate of convergence. Therefore, an order 1 Markov condition is insufficient to alter the limiting behaviour of a random walk.  

Следващата сбирка на Семинара по геометрия на МЦМН ще се проведе в сряда, 24 април 2024 г. от 16:00 ч. в зала 403: Доклад на тема Generalised Plucker formula ще изнесе Андрей Бенгуш-Ласние, МЦМН. Abstract: In order to classify objects in singularity theory and algebraic geometry, we define invariants associated to varieties or germs of singularities and hope to have enough tools to compute them easily. From classical projective duality, for any variety X , we can define a dual variety X∗ and we call the class of X the degree of X∗ . Plücker’s formula allows one to compute this class for plane curves with a certain set of nodes, cusps and tacnodes. We will start our talk by recalling the [...]

Поредната сбирка на семинара Дидактическо моделиране ще се проведе на 29.04.2024 г. от 14:30 ч. в зала 278 на ИМИ. Доклад на тема Дидактически моменти от последните десетилетия ще изнесe проф. Борислав Лазаров.

Следващата сбирка на Семинара по геометрия на МЦМН ще се проведе в сряда, 15 май 2024 г. от 16:00 ч. в зала 403 и онлайн в Zoom: Доклад на тема Hyperbolic amoebas ще изнесе Михаил Школников, ИМИ - БАН. Abstract: Classical amoebas serve as a tool to study algebraic varieties and as one of the entry points to tropical geometry. The original definition involves a logarithmic projection of a subvariety of a complex algebraic torus, which can be interpreted as forgetting the phase, i.e. the arguments of complex numbers. In group-theoretic terms, this projection map may be thought of as passing to the quotient by the maximal compact subgroup. Suppose one replaces the algebraic torus with a complex three-dimensional matrix group. In that case, [...]

На 16 май (четвъртък) от 16:15 часа в зала 502 на ФМИ, ВТУ предстои поредната сбирка на семинара Математически основи на информатиката. Доклад на тема Lee distance in analyzing and modeling rank data ще изнесе Николай И. Николов, главен асистент в секция ИОВС на ИМИ. Резюме: Distances on permutations are commonly used in rank data analysis and are an efficient tool for constructing probability models for rankings. In this talk, we consider some probabilistic applications of the Lee distance, which was originally developed as a generalization of the Hamming distance for error correction coding in modulation. In particular, we study the “K-means” clustering procedure based on Lee distance and approximate the normalizing constant needed for assessing the number of clusters. Furthermore, several asymptotic properties of the random [...]

Поредната сбирка на семинара Дидактическо моделиране ще се проведе на 20.05.2024 г. от 14:30 ч. в зала 278 на ИМИ. Доклад на тема Аксиоматика и построяване на планиметрията на векторна основа ще изнесe доц. Бойко Банчев.

An efficient approach for searching three-body periodic orbits passing through Euler configuration Докладчик: Иван Христов (ФМИ-СУ) Дата: 28.05.2024 г. Час: 15:00 ч. Място: зала 503 Резюме: The classic gravitational three-body problem is considered. The motion of the bodies is determined by Newton’s second law and Newton’s law of universal gravitation. We are interested in a special case of planar periodic orbits – those that pass through Euler configuration. In this talk a new efficient approach for searching three-body periodic equal-mass collisionless orbits passing through Euler configuration is presented [1]. The approach is based on a symmetry property of the solutions at the half period. Depending on two previously established symmetry types on the shape sphere, each solution is presented by one or two distinct initial [...]

Поредната сбирка на Националния семинар по стохастика ще се проведе на 4 юни 2024 г. (сряда) от 14:00 часа в зала 503 на ИМИ - БАН. Доклад на тема Comparison of parameter estimation methods for a Beta-Uniform mixture model ще изнесе Николай И. Николов (ИМИ-БАН). Абстракт. The Benjamini-Hochberg (B-H) method is a procedure for controlling the false discovery rate in the problem of multiple comparisons and is one of the most cited scientific works. In this talk, a Beta-Uniform mixture is considered for approximating the distribution of the p-values before the B-H adjustment. Expectation-maximization algorithms are derived for finding the maximum-likelihood and the maximum product of spacings estimations of the parameters in the suggested model. In addition, the method of moments is also applied for [...]

На 7 юни 2024 г. (петък) от 12:30 часа в зала 503 на ИМИ ще се проведе присъствено заседание на семинара по „Алгебра и логика”. Доклад на тема: Some Properties and Applications of Kloosterman Sums on Finite Fields ще изнесе Любомир Борисов, ИМИ - БАН. Абстракт Поканват се всички желаещи да присъстват. От секция „Алгебра и логика” на ИМИ – БАН http://www.math.bas.bg/algebra/seminarAiL/ ============================== =====================

В петък (07.06) от 14:00 часа в зала 403 на ИМИ ще се състои съвместна сбирка на семинарите на МЦМН и секция МОИ. Доклад на тема: Multivariate P- and Q-polynomial association schemes ще изнесе  Eiichi Bannai (Kyushu University). https://icms.bg/multivariate-p-and-q-polynomial-association-schemes-talk-by-eiichi-bannai/

На 11-ти юни (вторник) от 14:00 ч. в зала 503 на ИМИ ще се състои сбирка на Семинара по Изследване на операциите. Доклад на тема Mathematical modelling of torque-velocity and torque-angle relationships ще изнесе проф. Петър Миланов, ИМИ-БАН и ЮЗУ.