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.