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/ ============================== =====================

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.

На 18-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 - part 2: numerical results ще изнесе проф. Петър Миланов, ИМИ-БАН и ЮЗУ.

СЪЮЗ НА МАТЕМАТИЦИТЕ В БЪЛГАРИЯ ИНСТИТУТ ПО МАТЕМАТИКА И ИНФОРМАТИКА – БАН НАЦИОНАЛЕН КОЛОКВИУМ ПО МАТЕМАТИКА ​Поредната сбирка на Колоквиума ще се състои на 26 юни 2024 г. (сряда)  от 16:15 часа в Заседателната зала на ИМИ - БАН. Доклад на тема: Устойчивост на нелинейни вълни ще изнесе проф. дмн Севджан Хаккъев, Институт по матем​атика и информатика, Българска академия на науките. ​Резюме

На 01.07.2024 г. от 14:00 ч. в стая 578 на ИМИ и онлайн в Zoom ще се състои поредната сбирка на семинара по Диференциални уравнения и математическа физика. Доклад на тема p-Adic Numbers, Neural Networks, Deep Learning, and Statistical Field Theories ще изнесе Prof. W. A. Zuniga-Galindo from University of Texas Rio Grande Valley. АБСТРАКТ The talk aims to glimpse our recent research work on the mathematical foundations of hierarchical neural networks.  I plan to cover the following topics: (1) the non-Archimedean Wilson-Cowan Model; (2) p-adic Cellular Neural Networks; (3) p-Adic Statistical Field Theory and Deep Boltzmann Machines. In the first part of the talk, I present a hierarchical version of the Wilson-Cowan model, one of the most relevant models in theoretical neuroscience (see [...]

На 2-ри юли (вторник) от 14:00 ч. в зала 503 на ИМИ ще се състои сбирка на Семинара по Изследване на операциите. Доклад на тема On some contemporary mathematical methods for data analysis ще изнесе проф. Пандо Георгиев, ИМИ-БАН. Абстракт: We will review some selected methods and algorithms for data analysis: A) Latent component analysis - reveals hidden features of composite data. Particularly, we will describe some     Signal Separation Methods: based on statistical independence - Independent Component Analysis based on sparsity. - Sparse Component Analysis based on non-negativity - Non-Negative Matrix and Tensor Factorization B) New approach to multiclass learning problems and applications to some problems in machine learning, as: nonlinear least square problems subspace clustering and non-linear skeletons reconstruction of several [...]

На 03.07.2024 г. от 14:00 ч. в зала 478 на ИМИ и дистанционно в Zoom ще се състои поредната сбирка на семинара по Диференциални уравнения и математическа физика. Доклад на тема МЕТОД НА ТОЧНА ДИАГОНАЛИЗАЦИЯ В ОБЛАСТТА НА МОЛЕКУЛНИЯ МАГНЕТИЗЪМ ще изнесе д-р Мирослав Георгиев. Абстракт. Малко след възникването на наномагнетизма, като самостоятелна подобласт на магнетизма, стремежът към синтезирането на молекулни магнити с подходящи за приложение в сферата на нанотехнологиите магнитни свойства заема основно място сред изследванията в областта [1-3]. Това поражда необходимостта от по-задълбочено познаване на микроскопичната динамика стояща в основата на магнитните свойства на тези системи. Ето защо прилагането на първопринципни теоретични изследвания, включващи математични методи като матрица на плътността, точна диагонализация и квантова теория на пертурбациите, насочени в това направление се радват на [...]

Поредната сбирка на Националния семинар по стохастика ще се проведе на 3 юли 2024 г. (сряда) от 14:00 часа в зала 503 на ИМИ - БАН. Доклад на тема Control Problems for Queuing Systems with Moving Servers ще изнесе Asaf Hajiyev (Azerbaijan National Academy of Sciences, Institute of Control systems). Абстракт. For queuing systems with moving servers, the control policy which means delays of a beginning service is introduced. In the capacity of efficiency index of systems is taken a customer’s average waiting time before service. Although it seems that it is a paradoxical idea to delay the beginning of service, it has been proved that for some systems it gives a gain in a customer’s average waiting time before service. The class of [...]

На 9 юли 2024 г. (вторник) 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 Linear and polycyclic codes over some affine algebra rings ще изнесе Edgar Martìnez-Morо, University of Valladolid, Castilla, Spain Проф. Едгар Мартинез-Моро гостува в София в рамките на Научна програма "Повишаване на изследователския капацитет в областта на математическите науки" (ПИКОМ). Абстракт и кратка биографична справка за проф. Моро може да прочетете тук.

На 10 юли 2024 г. (сряда) 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 A Bollobás-type problem: from root systems to Erdős–Ko–Rado ще изнесе Qendrim Gashi, Department of Mathematics, University of Prishtina   Абстракт може да прочетете тук.

Дата: 06.08.2024 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: проф. Младен Димитров (Университет на Лил) Доклад: P-adic L-functions and the geometry of the Eigencurve Допълнителна информация: https://icms.bg/p-adic-l-functions-and-the-geometry-of-the-eigencurve-talk-by-mladen-dimitrov/ Резюме. For centuries, understanding special values of L-functions has been a significant research topic in number theory. Their study has been central to many celebrated pieces of mathematics, from Dirichlet’s theorem on primes in arithmetic progressions and the class number formula to the Riemann hypothesis and the Birch and Swinnerton-Dyer (BSD) conjecture, two of the famous millennium problems. The BSD conjecture predicts that the Mordell–Weil rank of an elliptic curve is given by the order of vanishing of its L-function the central point. Iwasawa theory, in turn, seeks to relate the arithmetic over the p-adic [...]

About maximal distance minimizers. What is it and why they are so good? Докладчик: Яна Теплицкая Дата: 03.09.2024 г. Час: 14:00 ч. Място: зала 256 Резюме  

Дата: 10.09.2024 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: Боаз Моерман (Утрехтски университет) Доклад: Generalized integral points and strong approximation Допълнителна информация: https://icms.bg/generalized-integral-points-and-strong-approximation-talk-by-boaz-moerman/ Резюме. The Chinese remainder theorem states that given coprime integers p_1, …, p_n and integers a_1, …, a_n , we can always find an integer m such that m \equiv a_i \mbox{ mod } p_i for all i . Similarly given distinct numbers x_1,…, x_n and y_1, …, y_n we can find a polynomial f such that f(x_i)=y_i . These statements are two instances of strong approximation for the affine line (over the integers \mathbb{Z} and the polynomials k[x] over a field k ). In this talk we will consider [...]

Subdiffusion-reaction systems: from microscopic random walk to the mesoscopic fractional PDE's Докладчик: проф. Сергей Федотов, ръководител на групата по приложна математика в университета на Манчестър Дата: 11.09.2024 г. Час: 14:00 ч. Място: зала 403 Резюме: An interesting feature of subdiffusion-reaction systems is the lack of a universal model for reactions in subdiffusive media. Consequently, the coarse-grained fractional subdiffusion-reaction equations depend on the specific details of the underlying microscopic random walk models. This complexity arises from the memory effects inherent in subdiffusive transport systems. Simply adding a reaction term to the transport equation can be physically inconsistent. Due to the memory effect, the subdiffusion process depends on the entire history of the system’s evolution making the diffusion and reaction processes inseparable.  

На 11.09.2024 г. от 14:00 ч. в зала 478 на ИМИ и онлайн в Zoom ще се състои поредната сбирка на семинара по Диференциални уравнения и математическа физика. Доклад на тема Wigner’s elementary systems in de Sitter spacetime ще изнесе Хамед Педжан. Абстракт. Quantum elementary systems are associated with (projective) unitary irreducible representations (UIRs) of the relativity group (or one of its covering groups). This foundational perspective was first introduced by Wigner in his seminal 1939 paper, within the framework of Einstein-Poincaré relativity. In this talk, building on Wigner's approach, we will briefly introduce the de Sitter relativity group, its representations, and outline the basics of constructing elementary systems within the global structure of de Sitter spacetime. Линка към Зуум стаята: Join Zoom Meeting [...]

Поредната сбирка на СЕМИНАРА на секция "Математическо моделиране и числен анализ" ще се състои на  18.09.2024 (сряда), от 14:00 часа в зала 478 на Института по математика и информатика. Доклад на тема: Singular perturbation theory in epidemic modelling ще изнесе Sara Sottile (University of Bologna, Italy). Резюме: In real world scenarios, the natural phenomena usually evolve on time scales differing by various orders of magnitude. Such separation in time-scales can be found, for example, in the field of chemical oscillations [1], neuroscience [2], ecology [3] or opinion/information spreading [4]. In this context, Geometric Singular Perturbation Theory (GSPT) is a powerful analytical technique which fully exploits the underlying time-scale separation. Epidemiological models also provide a natural fit for these dynamics. Consider, for instance, models that [...]

Поредната сбирка на семинара Дидактическо моделиране ще се проведе на 30.09.2024 г. от 14:30 ч. в зала 278 на ИМИ. Доклад на тема Подготовка на България за Младежката Балканска олимпиада по математика - материали и препоръки за ученици, учители и ръководители ще изнесe ас. Мирослав Маринов.

На 1 октомври (вторник) от 14:00 ч. в зала 503 на ИМИ ще се състои сбирка на Семинара по Изследване на операциите. Доклад на тема Graphs as an universal modeling tool ще изнесе проф. Никола Янев, ИМИ-БАН. Абстракт: For a series of practical optimization problems, we show that formulating them as graph optimization problems enables the development of competitive algorithms. The problems considered are known as: protein threading problem, contact map overlap, HP folding, a new scheduling theory problem, classification problem and the biclustering problem. The focus is on formulating them as graph optimization problems, which are solved by using Integer programming techniques.

На 2 октомври 2024 г. (сряда) от 14:00 часа в зала 478 на ИМИ-БАН ще се състои поредната сбирка на семинара на секция „Математически основи на информатиката". Доклад на тема Lipschitz Permutations on Certain Graphs ще изнесе Драгомир Грозев. Абстракт

На 9 октомври (сряда) от 14:00 ч. в зала 503 на ИМИ ще се състои сбирка на Семинара по Изследване на операциите. Доклад на тема Graphs as an universal modeling tool, част 2 ще изнесе проф. Никола Янев, ИМИ-БАН. Абстракт: For a series of practical optimization problems, we show that formulating them as graph optimization problems enables the development of competitive algorithms. The problems considered are known as: protein threading problem, contact map overlap, HP folding, a new scheduling theory problem, classification problem and the biclustering problem. The focus is on formulating them as graph optimization problems, which are solved by using Integer programming techniques.

Поредната сбирка на семинара Дидактическо моделиране ще се проведе на 14.10.2024 г. от 14:30 ч. в зала 278 на ИМИ. Доклад на тема Състезателни задачи с покриващи оцветявания в СтруниМа ще изнесe д-р Младен Вълков.

Поредното заседание на Общия семинар на секция "Анализ, геометрия и топология" ще се проведе на 15 октомври 2024 г. от 14:00 часа в зала 478 на ИМИ - БАН. Доклад на тема: Unimodality Preservation by Ratios of Functional Series and Integral Transforms ще изнесе Dmitrii Karp, Holon Institute of Technology, Holon, Israel. Поканват се всички интересуващи се. Резюме. Elementary, but very useful lemma due to Biernacki and Krzyz (1955) asserts that the ratio of two power series inherits monotonicity from that of the sequence of ratios of their corresponding coefficients. Over the last two decades it has been realized that, under some additional assumptions, similar claims hold for more general series ratios and integral transforms as well as for unimodality in place of monotonicity. [...]

На 15 октомври (вторник) от 14:00 ч. в зала 503 на ИМИ ще се състои сбирка на Семинара по Изследване на операциите. Доклад на тема Asymptotic covariance matrix of Capon’s Maximum likelihood estimator and application of steered response power phase alignment algorithm in seismic array data processing ще изнесе Александр Варипаев от секция ИОСВ. Абстракт: Capon’s estimator was originally developed for frequency-wavenumber power spectral density analysis. Theoretically, it can be treated as maximum likelihood estimator of unknown vector parameter of multidimensional linear system (MLS) model with one input and m outputs.  Practically important and non-trivial case is considered, when the number of nuisance parameters, which are values of input deterministic signal, tends to infinity. Under assumptions that MLS output signals distorted by random Gaussian stationary  [...]

Поредното заседание на Общия семинар на секция "Анализ, геометрия и топология" ще се проведе на 22 октомври 2024 г. от 14:00 часа в зала 478 на ИМИ - БАН. Доклад на тема: Higher order estimates for Monge-Ampere type equations motivated by quaternionic geometry ще изнесе Marcin Sroka, Jagiellonian University, Kraków, Poland. Поканват се всички интересуващи се. Резюме. In the talk I will discuss obstacles for obtaining higher order a priori estimates for equation introduced by Alesker and Verbitsky in 2010 on HKT manifolds in relation to Calabi type conjecture on those manifolds (and similar type PDEs studied since on hypercomplex manifolds). After presenting the state of art, I will focus on the key second order estimate. For the real Monge-Ampere equation on Riemannian manifolds [...]

На 22 октомври (вторник) от 14:00 ч. в зала 503 на ИМИ ще се състои сбирка на Семинара по Изследване на операциите. Доклад на тема Asymptotic covariance matrix of Capon’s Maximum likelihood estimator and application of steered response power phase alignment algorithm in seismic array data processing - част 2 ще изнесе Александр Варипаев от секция ИОСВ. Абстракт: Capon’s estimator was originally developed for frequency-wavenumber power spectral density analysis. Theoretically, it can be treated as maximum likelihood estimator of unknown vector parameter of multidimensional linear system (MLS) model with one input and m outputs.  Practically important and non-trivial case is considered, when the number of nuisance parameters, which are values of input deterministic signal, tends to infinity. Under assumptions that MLS output signals distorted by [...]

Поредната сбирка на семинара Дидактическо моделиране ще се проведе на 28.10.2024 г. от 14:30 ч. в зала 278 на ИМИ. Доклад на тема Старият (не)познат Logo: примери, идеи, пропускани възможности ще изнесe доц. Бойко Банчев.

На 22 ноември 2024 г. (петък) от 13:00 часа в зала 578 на ИМИ ще се проведе присъствено заседание на семинара по „Алгебра и логика”. Доклад на тема: On Köthe’s normality question for locally finite-dimensional central division algebras ще изнесе Иван Чипчаков, ИМИ - БАН. Абстракт. This talk considers Köthe's question of whether every associative locally finite-dimensional (abbr., LFD) central division algebra R over a field K is a normally locally finite (abbr., NLF) algebra over K, that is, whether every nonempty finite subset Y of R is contained in a finite-dimensional central K-subalgebra RY of R. It shows that the answer to the posed question is negative if K is a purely transcendental extension of infinite transcendence degree over an algebraically closed field k. On the other hand, central [...]

Поредната сбирка на семинара Дидактическо моделиране ще се проведе на 25.11.2024 г. от 14:30 ч. в зала 278 на ИМИ. Доклад на тема Анализ на резултатите от Есенния математически турнир ще изнесe Невена Събева-Колева.

Следващата сбирка на Семинара по геометрия на МЦМН ще се проведе в сряда, 27 ноември 2024 г. от 16:00 ч. в зала 403 и онлайн в Zoom: Доклад на тема Tropical compactifications of moduli spaces ще изнесе Лайънъл Ланг, Международен център по математически науки (МЦМН - София). Abstract: In this talk I will describe various tropical compactifications of the moduli spaces of curves. I will discuss some motivations and applications coming from tropical geometry (joint with M. Melo, J. Rau and F. Viviani). Zoom link: https://us02web.zoom.us/j/83740034721?pwd=VnBtcVpGUktscHQ4a09jZkNZTURyZz09

Следващата сбирка на Семинара по геометрия на МЦМН ще се проведе в сряда, 4 ДЕКЕМВРИ 2024 г. от 16:00 ч. в зала 403 и онлайн в Zoom: Доклад на тема Tropical compactifications of moduli spaces - Part 2 ще изнесе Лайънъл Ланг, Международен център по математически науки (МЦМН - София). Abstract: In this talk I will describe various tropical compactifications of the moduli spaces of curves. I will discuss some motivations and applications coming from tropical geometry (joint with M. Melo, J. Rau and F. Viviani). Zoom link: https://us02web.zoom.us/j/83740034721?pwd=VnBtcVpGUktscHQ4a09jZkNZTURyZz09

На 5 декември 2024 г. (четвъртък) от 15:30 ч. в зала 478 на ИМИ-БАН, в рамките на семинара на секция „Анализ, геометрия и топология“, проф. Емилия Бажлекова ще изнесе встъпителна академична лекция на тема: Приложения на дробното смятане в моделирането на процеси с памет Резюме: През последните години значителен научен интерес се проявява към така нареченото дробно смятане, което позволява интегриране и диференциране от произволен ред, не непременно целочислен. До голяма степен това се дължи на приложенията на дробното смятане в математическото моделиране на различни процеси с памет,  като например аномална дифузия и разпространение на вълни във вискоеластични среди. Започвайки от класическото уравнение на Ward-Tordai, в лекцията се дискутират редица дробни еволюционни уравнения, които описват процеси с памет. Основният фокус е върху изследването на [...]

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 8 януари 2025 г. от 17:00 часа в зала 401 на корпус 4 на ВТУ, на която Prof. Ferruh Özbudak Sabancı University Faculty of Engineering and Natural Sciences, İstanbul - Turkiye ще изнесе доклад на тема: Generalizing the Bierbrauer—Friedman bound to mixed-level orthogonal arrays (joint work with Denis Krotov and Vladimir Potapov) Abstract: We characterize mixed-level orthogonal arrays it terms of algebraic designs in a special multigraph. We prove a mixed-level analog of the Bierbrauer--Friedman (BF) bound for pure-level orthogonal arrays and show that arrays attaining it are radius-1 completely regular codes (equivalently, intriguing sets, [...]

Дата: 14.01.2025 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: Jean-Pierre Gazeau от Université Paris-Cité Доклад: Regularized Quantum Motion in a Bounded Set: Hilbertian Aspects Допълнителна информация: https://icms.bg/regularized-quantum-motion-in-a-bounded-set-hilbertian-aspects-talk-by-jean-pierre-gazeau/ Резюме. It is well known that the momentum operator canonically conjugated to the position operator for a particle confined within a bounded interval of the line (with Dirichlet boundary conditions) is not essentially self-adjoint, as it possesses a continuum of self-adjoint extensions. In this talk, we demonstrate that essential self-adjointness can be restored by symmetrically weighting the momentum operator with a positive bounded function that approximates the indicator function of the given interval. This weighted momentum operator arises naturally from a similarly weighted classical momentum through the Weyl-Heisenberg covariant integral quantization of functions or distributions. Reference: [...]

Поредната сбирка на СЕМИНАРА на секция "Математическо моделиране и числен анализ" ще се състои на  30.01.2025 г. (четвъртък) от 14:00 часа по Zoom. Доклад на тема: Some mathematical aspects of simulation modeling of physiological processes in plants ще изнесе Dr. Alex Topaj (Bureau Hyperborea Ltd). Резюме: The contribution presents the author's experience of using mathematical methods to describe plant physiology processes in applied crop models. In contrast to the simplified data-based empirical approach, the mechanistic description of plant vital processes in theory allows us to obtain new knowledge and to develop the universal crop models with parameters having physical meaning. Such explanatory models, in addition to the traditional cause-and-effect method (the flow-balance approach, leading to systems of differential or difference equations), can also successfully apply [...]

Дата: 04.02.2025 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: Мирослав Георгиев, Институт по математика и информатика, Българска академия на науките Доклад: Yukawa regulators in electrodynamics: Exact approach to the self-energy and anomalous g-factor Допълнителна информация: https://icms.bg/yukawa-regulators-in-electrodynamics-exact-approach-to-the-self-energy-and-anomalous-g-factor-icms-seminar-talk-by-miroslav-georgiev/ Резюме. In the present talk, we will discuss the prospect of electrodynamics in quantifying the self-interaction of a non-composite charged particle. We will demonstrate that under the consideration of unique to the particle Yukawa cut-offs the radial singularity in corresponding electromagnetic field potentials’ is removed allowing the classical theory to admit exact solutions for the particle’s self-energy and anomalous g-factor. Highly accurate results for the electron’s and muon’s anomalous g-factor will be presented, with calculated values matching the most recent measurements reported in the literature [...]

Дата: 11.02.2025 г., 14:00 ч. Място: Зала 403, ИМИ - БАН Докладчик: Sergey Favorov, Department of Pure Mathematics, Kharkov National University, Ukraine Доклад: Fourier quasicrystals and their generalizations, zeros of Dirichlet series, other almost periodic objects Допълнителна информация: https://icms.bg/fourier-quasicrystals-and-their-generalizations-zeros-of-dirichlet-series-other-almost-periodic-objects-icms-seminar-talk-by-sergey-favorov/ Резюме. A complex measure \mu on a d -dimensional Euclidean space is a crystalline measure (CM) if it is the temperate distribution, its distributional Fourier transform \hat\mu is also a measure, and supports of \mu and \hat\mu are discrete (locally finite); \mu is a Fourier quasicrystal (FQ) if, in addition, |\mu| and |\hat\mu| are also temperate distributions. For example, if \mu_0 is the sum of the unit masses at all points with integer coordinates, then by Poisson’s [...]

На 21 февруари 2025 г. (петък) от 13:00 часа в зала 578 на ИМИ ще се проведе присъствено заседание на семинара по „Алгебра и логика”. Доклад на тема: Classification of C*-algebras through the lens of Cartan subalgebras ще изнесе Ali Raad (Американски университет в България). Абстракт. C*-algebras were introduced in the last century following various attempts to mathematically formalize the foundations of quantum mechanics. As such they encapsulate the study of noncommutative topology, as every C*-algebra is an algebra of bounded operators on some Hilbert space. Over the years there has been a significant attempt to classify C*-algebras by an invariant consisting of K-theoretic and tracial data. A recent breakthrough result has shown that every classifiable C*-algebra has a distinguished Abelian subalgebra called a Cartan [...]

На 14 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: Protection Against Noise for a Type of Quantum Computation ще изнесе Валентин Илиев (ИМИ-БАН). Абстракт. In this presentation we establish necessary and sufficient conditions for some pairs of quantum logic gates which operate on one qubit to be protected against crosstalk. More precisely, it is devoted to the protection against noise for measurement-based quantum computation. We use the notions of (in)dependence of two events in an appropriate classical probability space and the related informational (in)dependence.   Линк към zoom-стаята на семинара: Https://us02web.zoom.us/j/85137375021?pwd=RE5QczdFTE1xL1R6MnI2b1lkcGczQT09 Поканват се всички желаещи да присъстват. От секция „Алгебра и логика” [...]

На 18-ти март (вторник) от 14:00 ч. в зала 503 на ИМИ ще се състои сбирка на Семинара на секция ИОВС.  Доклад на тема: Числено обратно моделиране за идентифициране на волатилността от опционни котировки ще изнесе гл. ас. Слави Георгиев Георгиев, ИМИ-БАН. Резюме. Волатилитетът е един от най-важните параметри, като едновременно с това не е пряко наблюдаем на пазара. В този доклад представяме някои подходи за идентифициране на изменчивостта като функция на времето, когато се знае някаква информация за опционната премия. Използваме усредняваща линеаризация по времето на дифузионните членове на начално-граничните задачи. След това разлагаме приближеното решение по отношение на волатилността, за да пристъпим към новия времеви слой в дискретната задача. Тези подходи са тествани с реални и симулирани данни за европейски и други типове [...]

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, [...]

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.  

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 [...]

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 [...]

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 [...]

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 [...]

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 [...]

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 [...]

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 [...]

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\{ [...]

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 [...]

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 [...]

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 [...]