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National Seminar on Probability and Statistics

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the National Seminar on Probability and Statistics will be held on June 4, 2024, at 2:00 p.m. in Room 503 of the Institute of Mathematics and Informatics. A talk on: Comparison of parameter estimation methods for a Beta-Uniform mixture model will be delivered by Nikolay I. Nikolov (IMI - BAS). Abstract.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 [...]

Algebra and Logic Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Algebra and Logic Seminar will be held online via Zoom on April 12, 2024 (Friday) at 1:00 pm (UTC+2). A talk on: On an Aspect of Second Quantum Revolution will be delivered by Valentin Iliev, IMI - BAS. Abstract.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. [...]

Operations Research Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Operations Research Seminar will be held on June 11th (Tuesday) at 2:00 pm in Room 503 of IMI - BAS. A talk on Mathematical modelling of torque-velocity and torque-angle relationships will be held by Prof. Peter Milanov, IMI - BAS and South-West University.

Mathematical Foundations of Informatics Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Mathematical Foundations of Informatics seminar will be held on June 11, 2024, at 3 p.m. in Room 503 of the Institute of Mathematics and Informatics. A talk on: Hadamard matrices with automorphisms of prime order and related codes will be delivered by Vladimir D. Tonchev Michigan Technological University, Houghton, USA. The abstract can be found here.

Operations Research Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Operations Research Seminar will be held on June 18th (Tuesday) at 2:00 pm in Room 503 of IMI - BAS. A talk on Mathematical modelling of torque-velocity and torque-angle relationships  - part 2: numerical results will be held by Prof. Peter Milanov, IMI - BAS and South-West University.

National Mathematics Colloquium

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

UNION OF BULGARIAN MATHEMATICIANS INSTITUTE OF MATHEMATICS AND INFORMATICS, BULGARIAN ACADEMY OF SCIENCES NATIONAL MATHEMATICS COLLOQUIUM The next meeting of the National Mathematics Colloquium will be held on June 6, 2024 (Wednesday) at 4:15 pm EET (UTC +2) in the Conference Room of IMI - BAS. A talk on: Stability of periodic waves will be delivered by Prof. Sevdzhan Hakkaev, Institute of Mathematics and Informatics, Bulgarian Academy of Sciences. Abstract Everybody is invited.  

Differential Equations and Mathematical Physics Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Differential Equations and Mathematical Physics Seminar will be held on July 1, 2024, at 2:00 pm, in Room 578 of IMI - BAS and online in Zoom. A talk on p-Adic Numbers, Neural Networks, Deep Learning, and Statistical Field Theories will be delivered by Prof. W. A. Zuniga-Galindo from University of Texas Rio Grande Valley. ABSTRACT 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 [...]

Operations Research Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Operations Research Seminar will be held on July 2nd (Tuesday) at 2:00 pm in Room 503 of IMI - BAS. A talk on On some contemporary mathematical methods for data analysis will be held by Prof. Pando Georgiev, IMI - BAS. Abstract: 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 [...]

Differential Equations and Mathematical Physics Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Differential Equations and Mathematical Physics Seminar will be held on July 3, 2024, at 2:00 pm, in Room 478 of IMI - BAS and online in Zoom. A talk on METHOD OF PRECISE DIAGONALIZATION IN THE FIELD OF MOLECULAR MAGNETISM will be delivered by Dr. Miroslav Georgiev. Topic: Доклад на д-р Мирослав Георгиев Time: Jul 3, 2024 14:00 Sofia Join Zoom Meeting https://us02web.zoom.us/j/87099331737?pwd=w8894QHkbq1UTc2n3qr7dC7yTLPYI6.1 Meeting ID: 870 9933 1737 Passcode: 263339

National Seminar on Probability and Statistics

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the National Seminar on Probability and Statistics will be held on July 3, 2024, at 2:00 p.m. in Room 503 of the Institute of Mathematics and Informatics. A talk on: Control Problems for Queuing Systems with Moving Servers will be delivered by Asaf Hajiyev (Azerbaijan National Academy of Sciences, Institute of Control systems). Abstract.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 [...]

Mathematical Foundations of Informatics Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Mathematical Foundations of Informatics seminar will be held on July 09, 2024, at 3 p.m. in Room 256 of the Institute of Mathematics and Informatics. A talk on: Linear and polycyclic codes over some affine algebra rings will be delivered by Edgar Martìnez-Morо, University of Valladolid, Castilla, Spain The abstract can be found here.

Mathematical Foundations of Informatics Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Mathematical Foundations of Informatics seminar will be held on July 10, 2024, at 3 p.m. in Room 256 of the Institute of Mathematics and Informatics. A talk on: A Bollobás-type problem: from root systems to Erdős–Ko–Rado will be delivered by Qendrim Gashi, Department of Mathematics, University of Prishtina   The abstract can be found here.

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Time: August 6, 2024, 2:00 pmPlace: Room 403, IMI - BASSpeaker: Prof. Mladen Dimitrov Brown  (University of Lille)Title: P-adic L-functions and the geometry of the EigencurveFurther information: https://icms.bg/p-adic-l-functions-and-the-geometry-of-the-eigencurve-talk-by-mladen-dimitrov/Abstract. 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 cyclotomic extension with the [...]

Applied Mathematics Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Subdiffusion-reaction systems: from microscopic random walk to the mesoscopic fractional PDE's Speaker: Yana Teplitskaya Date: September 3, 2024 Time: 2:00 pm Place: Room 256, IMI - BAS Abstract

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Time: September 10, 2024, 2:00 pm Place: Room 403, IMI - BAS Speaker: Boaz Moerman (Utrecht University) Title: Generalized integral points and strong approximation Further information: https://icms.bg/generalized-integral-points-and-strong-approximation-talk-by-boaz-moerman/ Abstract. 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 [...]

Applied Mathematics Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Subdiffusion-reaction systems: from microscopic random walk to the mesoscopic fractional PDE's Speaker: Prof. Sergei Fedotov, head of the applied group of the Mathematics Department of the University of Manchester Date: September 11, 2024 Time: 2:00 pm Place: Room 403, IMI - BAS Abstract: 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 [...]

Differential Equations and Mathematical Physics Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Differential Equations and Mathematical Physics Seminar will be held on September 11, 2024, at 2:00 pm, in Room 478 of IMI - BAS and online in Zoom. A talk on Wigner’s elementary systems in de Sitter spacetime will be delivered by Hamed Pejhan. Abstract: 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. Zoom [...]

Mathematical Modelling and Numerical Analysis Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the seminar of the Mathematical Modeling and Numerical Analysis Department  will be held on September 18, 2024, at 2:00 pm in Room 478 of the Institute of Mathematics and Informatics. A talk on: Singular perturbation theory in epidemic modelling will be delivered by Sara Sottile (University of Bologna, Italy). Abstract: 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 [...]

Didactical Modeling Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the seminar Didactical Modeling will be held on September 30, 2024, at 2:30 pm in Room 278 of IMI – BAS. A talk on: Preparation of Bulgaria for the Junior Balkan Mathematical Olympiad - resources and recommendations for students, teachers and leaders will be delivered by Assist. Prof. Miroslav Marinov.

Operations Research Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Operations Research Seminar will be held on October 1st (Tuesday) at 2:00 pm in Room 503 of IMI - BAS. A talk on Graphs as an universal modeling tool will be held by Prof. Nicola Yanev, IMI-BAN. Abstract: 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.

Mathematical Foundations of Informatics Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Mathematical Foundations of Informatics seminar will be held on October 2, 2024, at 2:00 p.m. in Room 478 of the Institute of Mathematics and Informatics. A talk on: Lipschitz Permutations on Certain Graphs will be delivered by Dragomir Grozev. Abstract

Operations Research Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Operations Research Seminar will be held on October 9th (Wednesday) at 2:00 pm in Room 503 of IMI - BAS. A talk on Graphs as an universal modeling tool, Part 2 will be held by Prof. Nicola Yanev, IMI-BAN. Abstract: 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.

Didactical Modeling Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the seminar Didactical Modeling will be held on October 14, 2024, at 2:30 pm in Room 278 of IMI – BAS. A talk on: Competition problems with covering colorings in StruniMa will be delivered by Dr. Mladen Valkov.

Joint Seminar of the Analysis, Geometry and Topology Department

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Joint Seminar of Analysis, Geometry and Topology Department will be held on October 15, 2024 at 2:00 pm (UTC+2)  in Room 478 of IMI. A talk on: Unimodality Preservation by Ratios of Functional Series and Integral Transforms  will be delivered by Dmitrii Karp, Holon Institute of Technology, Holon, Israel. Everybody is invited. Abstract. 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. In [...]

Operations Research Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Operations Research Seminar will be held on October 15th (Tuesday) at 2:00 pm in Room 503 of IMI - BAS. A talk on Asymptotic covariance matrix of Capon’s Maximum likelihood estimator and application of steered response power phase alignment algorithm in seismic array data processing will be held by Alexandr Varipaev, Operations Research, Statistics and Probability Department. Abstract: 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 [...]

Joint Seminar of the Analysis, Geometry and Topology Department

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Joint Seminar of Analysis, Geometry and Topology Department will be held on October 22, 2024 at 2:00 pm (UTC+2)  in Room 478 of IMI. A talk on: Higher order estimates for Monge-Ampere type equations motivated by quaternionic geometry  will be delivered by Marcin Sroka, Jagiellonian University, Kraków, Poland. Everybody is invited. Abstract. 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 it [...]

Operations Research Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Operations Research Seminar will be held on October 22nd (Tuesday) at 2:00 pm in Room 503 of IMI - BAS. A talk on Asymptotic covariance matrix of Capon’s Maximum likelihood estimator and application of steered response power phase alignment algorithm in seismic array data processing, Part 2 will be held by Alexandr Varipaev, Operations Research, Statistics and Probability Department. Abstract: 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 [...]

Didactical Modeling Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the seminar Didactical Modeling will be held on October 28, 2024, at 2:30 pm in Room 278 of IMI – BAS. A talk on: The well (un)known Logo: examples, ideas, missed opportunities will be delivered by Assoc. Prof. Boyko Bantchev.

National Coding Theory workshop “Professor Stefan Dodunekov”

Парк-хотел "Севастократор, с. Арбанаси

The National Coding Theory workshop with international participation "Profesor Stefan Dodunekov" will be held from 21nd to 24th November 2024 in Hotel “Sevastokrator” (https://sevastokrator.com/) in the village of Arbanassi. The scientific program will be held on 22th and 23th November and includes short talks (up to 20 minutes), thesis presentations (up to 40 minutes) and discussions. To participate in the scientific program, please send a title and a short abstract (up to one page) to Peter Boyvalenkov, peter@math.bas.bg and Tsonka Baicheva, tsonka@math.bas.bg before 11.11.2024. The workshop includes the annual reports session of the Mathematical Foundations of Informatics Department, IMI-BAS, too.

Algebra and Logic Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Algebra and Logic Seminar will be held on November 22, 2024 (Friday) at 1:00 pm (UTC+2). A talk on: On Köthe’s normality question for locally finite-dimensional central division algebras will be delivered by Ivan Chipchakov, IMI - BAS. Abstract. 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 division LFD-algebras [...]

Didactical Modeling Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the seminar Didactical Modeling will be held on November 25, 2024, at 2:30 pm in Room 278 of IMI – BAS. A talk on: Analysis of the results of the Fall Mathematical Tournament will be delivered by Nevena Sabeva-Koleva.

Geometry Seminar of ICMS

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next session of the Geometry Seminar of ICMS will be held on Wednesday, November 27, 2024, at 4:00 pm, in room 403 and via Zoom. A talk on: Tropical compactifications of moduli spaces will be delivered by Lionel Lanf, International Center of Mathematical Sciences (ICMS - Sofia). 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  

Geometry Seminar of ICMS

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next session of the Geometry Seminar of ICMS will be held on Wednesday, December 4, 2024, at 4:00 pm, in room 403 and via Zoom. A talk on: Tropical compactifications of moduli spaces - Part 2 will be delivered by Lionel Lanf, International Center of Mathematical Sciences (ICMS - Sofia). 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  

Inaugural lecture of Prof. Emilia Bazhlekova

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

On December 5, 2024, at 3:30 pm in Room 478 of IMI - BAS, as part of the seminar of the Analysis, Geometry and Topolofy Department, Prof. Emilia Bazhlekova will deliver an inaugural lecture on: Applications of fractional calculus in modelling processes with memory

Mathematical Foundations of Informatics Seminar

Veliko Tarnovo University 2, Teodosiy Tarnovski Str., Veliko Tarnovo

The seminar on MATHEMATICAL FOUNDATIONS OF COMPUTER SCIENCE organized by the Department of Mathematical Foundations of Informatics at IMI - BAS and the Faculty of Mathematics and Informatics of Veliko Tarnovo University (VTU), would like to invite you to the next meeting on January 8, 2025 at 5:00 p.m. in room 401 of building 4 of VTU. Prof. Ferruh Özbudak Sabancı University Faculty of Engineering and Natural Sciences, İstanbul - Turkiye will deliver a talk on: 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 [...]

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Time: January 14, 2025, 2:00 pm Place: Room 403, IMI - BAS Speaker: Jean-Pierre Gazeau, Université Paris-Cité Title: Regularized Quantum Motion in a Bounded Set: Hilbertian Aspects Further information: https://icms.bg/regularized-quantum-motion-in-a-bounded-set-hilbertian-aspects-talk-by-jean-pierre-gazeau/ Abstract. 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: [...]

Mathematical Modelling and Numerical Analysis Seminar

Zoom

The next meeting of the seminar of the Mathematical Modeling and Numerical Analysis Department  will be held on January 30, 2025, at 2:00 pm in Zoom.  A talk on: Some mathematical aspects of simulation modeling of physiological processes in plants will be delivered by Dr. Alex Topaj (Bureau Hyperborea Ltd). Abstract: 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 [...]

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Time: February 4, 2025, 2:00 pm Place: Room 403, IMI - BAS Speaker: Miroslav Georgiev, Institute of Mathematics and Informatics, Bulgarian Academy of Sciences Title: Yukawa regulators in electrodynamics: Exact approach to the self-energy and anomalous g-factor Further information: https://icms.bg/yukawa-regulators-in-electrodynamics-exact-approach-to-the-self-energy-and-anomalous-g-factor-icms-seminar-talk-by-miroslav-georgiev/ Abstract. 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 [...]

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Time: February 11, 2025, 2:00 pm Place: Room 403, IMI - BAS Speaker: Sergey Favorov, Department of Pure Mathematics, Kharkov National University, Ukraine Title: Fourier quasicrystals and their generalizations, zeros of Dirichlet series, other almost periodic objects Further information: https://icms.bg/fourier-quasicrystals-and-their-generalizations-zeros-of-dirichlet-series-other-almost-periodic-objects-icms-seminar-talk-by-sergey-favorov/ Abstract. 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 [...]

Algebra and Logic Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Algebra and Logic Seminar will be held on February 21, 2025 (Friday) at 1:00 pm (UTC+2). A talk on: Classification of C*-algebras through the lens of Cartan subalgebras will be delivered by Ali Raad (American University in Bulgaria). Abstract.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 subalgebra. Cartan subalgebras [...]

Algebra and Logic Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Algebra and Logic Seminar will be held on March 14, 2025 (Friday) at 1:00 pm (UTC+2) in Room 578 of IMI-BAS and online via Zoom. A talk on: Protection Against Noise for a Type of Quantum Computation will be delivered by Valentin Iliev (IMI-BAS, Bulgaria). Abstract. 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. Zoom link for the seminar: Https://us02web.zoom.us/j/85137375021?pwd=RE5QczdFTE1xL1R6MnI2b1lkcGczQT09 Everybody is invited. Algebra and Logic Department, IMI [...]

Seminar in Operations Research, Probability and Statistics

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

On March 18 (Tuesday) at 2:00 p.m. in Room 503 of IMI, a meeting of the Seminar of the ORPS Department will be held. A talk on: Numerical inverse modelling of volatility identification from option quotes will be delivered by Slavi Georgiev, IMI-BAS. Abstract. The volatility is one of the most important parameters as well as it not directly observable on the market. In this talk we present some approaches to identify the time-dependent volatility, when some information about the option premium is known. We employ an average linearization in time of the diffusion terms of the initial-boundary problems. Then, we decompose the approximate solution with respect to the volatility in order to proceed to the new time layer in the discrete problem. These approaches [...]

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Time: March 25, 2025, 2:00 pm Place: Room 403, IMI - BAS Speaker: Mikhail Shkolnikov, IMI - BAS Title: Affine distance function Further information: https://icms.bg/category/icms-seminar/ Abstract. 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 [...]

Applied Mathematics Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

About m-ary Gray codes Speaker: Maria Pashinska, IMI - BAS Date: March 27, 2025 Time: 2:00 pm Place: Room 503, IMI - BAS Abstract: 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 [...]

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Time: March 27, 2025, 4:00 pm Place: Room 403, IMI - BAS Speaker: Luis Ugarte (University of Zaragoza, Spain) Title: Complex structures on Lie algebras and its application to the Hull-Strominger system Further information: https://icms.bg/category/icms-seminar/ Abstract. 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 [...]

Algebra and Logic Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Algebra and Logic Seminar will be held on March 128, 2025 (Friday) at 1:00 pm (UTC+2) in Room 578 of IMI-BAS and online via Zoom. A talk on: Graded algebras that are the sum of two homogeneous subalgebras will be delivered by Plamen Koshlukov (State University of Campinas, Brazil). Abstract. 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 [...]

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Time: April 11, 2025, 4:00 pm Place: Room 403, IMI - BAS Speaker: Felipe Espreafico Guelerman, Sorbonne Université - Paris Title: On Motivic and Arithmetic Donaldson-Thomas invariants Further information: https://icms.bg/category/icms-seminar/ Abstract. 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 [...]

Mathematical Modelling and Numerical Analysis Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the seminar of the Mathematical Modeling and Numerical Analysis Department  will be held on April 23, 2025, at 2:00 pm in Room 478 of IMI - BAS.  A talk on: Multiscale Leading Edge and Bulk Dynamics for Tumour Invasion in Fibrous Environment will be delivered by Dr. Dumitru Trucu (University of Dundee, Шотландия). Abstract: 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 [...]

Algebra and Logic Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Algebra and Logic Seminar will be held on April 25, 2025 (Friday) at 1:00 pm (UTC+2) in Room 578 of IMI-BAS. A talk on: Hilbert scheme of smooth projective curves and some easy examples will be delivered by 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 [...]

Joint meeting of the ICMS Seminar and the “Algebra and Logic” Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

A joint meeting of the ICMS Seminar and the "Algebra and Logic" Seminar will be held next Tuesday, with a talk by Georges Tomanov. The details are as follows. Tuesday, April 29-th, 2:00 pm, in room 403 of IMI-BAS. Georges Tomanov, 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. [...]

Geometry Seminar of ICMS

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next session of the Geometry Seminar of ICMS will be held on Wednesday, April 30, 2025, at 4:00 pm, in room 403 and via Zoom. A talk on: Binary Quadratic Forms and Conway’s Topographs (Lecture 1 of 3) will be delivered by Nikita Kalinin, Guangdong Technion Israel Institute of Technology. The next two lectures will be held on 07.05.2025 and 14.05.2025 at 4:00 pm. 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 [...]

Geometry Seminar of ICMS

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next session of the Geometry Seminar of ICMS will be held on Wednesday, May 7, 2025, at 4:00 pm, in room 403 and via Zoom. A talk on: Binary Quadratic Forms and Conway’s Topographs (Lecture 2 of 3) will be delivered by Nikita Kalinin, Guangdong Technion Israel Institute of Technology. The next lecture will be held on 14.05.2025 at 4:00 pm. 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: [...]

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

A meeting of the ICMS seminar will be held on May 13, 2205, at 2:00 pm, in Room 403 of IMI - BAS. Speaker: Milan Zlatanovic (University of Niš) Title: Non-symmetric gravitational theorys Abstract: 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. [...]

Inaugural lecture by Assoc. Prof. Shkolnikov

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The inaugural lecture by Assoc. Prof. Mikhail Shkolnikov at the Analysis, Geometry and Topology Department will be held on May 13, 2025, at 3:15 pm in Room 403 of IMI - BAS. Speaker: Mikhail Shkolnikov (IMI – BAS) Title: Introduction to amoebas and tropicalization Abstract: 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 [...]

Seminar in Operations Research, Probability and Statistics

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

On May 14 (Wednesday) at 3:00 p.m. in Room 503 of IMI, a meeting of the Seminar of the ORPS Department will be held. A talk on: Busy Beaver for n=5, or How Complex are the Simple Programs will be delivered by Georgi Georgiec, Faculty of Mathematics and Informatics, Sofia University. Abstract. How long can a Turing machine with 5 states and the alphabet {0,1} run before it stops? The tape is initially filled with zeros. Known as “Busy Beaver for n=5” or BB(5), the problem is understandable to any student interested in programming. Solving it took 40 years and demonstrated how complex semantic analysis of even microscopic programs is. The story was told in a fascinating way a year ago in Quanta Magazine: [...]

Algebra and Logic Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Algebra and Logic Seminar will be held on May 16, 2025 (Friday) at 1:00 pm (UTC+2) in Room 503 of IMI-BAS. A talk on: Grätzer-Schmidt Theorem in arithmetical transfinite recursion will be delivered by Soowhan Yoon (American University in Bulgaria). Abstract: We assess the reverse mathematical strength of the Grätzer-Schmidt theorem (GS) as a principle in second order arithmetic. The theorem GS was studied in an article by Katie Brodhead, Mushfeq Khan, Bjørn Kjos-Hanssen, William A. Lampe, Paul Kim Long V. Nguyen, and Richard A. Shore, where they establish the provability of GS in Π11 Comprehension (Π11-CA0) and its restrictive variant GSD in arithmetical comprehension (ACA0). It will be shown that the arithmetical transfinite recursion (ATR0) is sufficient to prove GS. [...]

Didactical Modeling Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the seminar Didactical Modeling will be held on June 2, 2025, at 2:35 pm in Room 278 of IMI – BAS. A talk on: Analysis of the results of the Fall Mathematical Tournament will be delivered by Miroslav Marinov.

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The ICMS seminar continues with a series of four lectures by Dr. Peter Dalakov, as follows: Dates: June 3rd, 6th, 10th, 13th, 2:00 pm Place: Room 403, ИМИ-БАН Speaker: Peter Dalakov (IMI and AUBG) Topic: Special Kaehler Geometry and some applications Abstract: In this short sequence of lectures we will discuss the notion of special Kaehler structure and some of its links to complex algebraic geometry, in particular, complex Lagrangians, variations of Hodge structures and algebraic integrable systems. The sequence will conclude with examples related to various moduli spaces of Higgs bundles on curves. For more information please visit the site of the ICMS Seminar: https://icms.bg/category/icms-seminar/  

Applied Mathematics Seminar

Zoom

The next meeting of the Applied Mathematics Seminar will be held online on June 3, 2025, at 3:00 pm: Join Zoom Meeting https://us02web.zoom.us/j/87588684853?pwd=4xPgBSVfxBwjV4P8hrsHn2rN9gWQGB.1 Meeting ID: 875 8868 4853 Passcode: 711528 A generalization of Meijer's G function motivated by probability Speaker: Dmitrii Karp Abstract: Meijer's G function appeared in probability in 1930-ies even before Meijer's work as the density of the product of independent beta variables and as the density of the likelihood ratio test for samples drawn from many classical probability distributions. It is defined by a contour integral of the appropriate ratio of gamma products (sometimes reducible to the inverse Mellin transform). Replacing the Euler gamma function by the Barnes double gamma function in this contour integral, we introduce a new family of special [...]

Algebra and Logic Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Algebra and Logic Seminar will be held on June 6, 2025 (Friday) at 12:30 pm (UTC+3) in Room 578 of IMI-BAS. A talk on: Holographic probe branes and artificial neural networks will be delivered by Veselin Filev (IMI - BAS). Abstract: In holography, flavour probe branes are used to introduce fundamental matter to the AdS/CFT correspondence. At a technical level, the probes are described by extremizing the DBI action and solving the Lagrange–Euler equations of motion. I will report on applications of artificial neural networks that allow direct minimization of the regularized DBI action (interpreted as a free energy) without the need to derive and solve the equations of motion. I will consider, as examples, magnetic catalysis of chiral symmetry [...]

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The ICMS seminar continues with a series of four lectures by Dr. Peter Dalakov, as follows: Dates: June 3rd, 6th, 10th, 13th, 2:00 pm Place: Room 403, ИМИ-БАН Speaker: Peter Dalakov (IMI and AUBG) Topic: Special Kaehler Geometry and some applications Abstract: In this short sequence of lectures we will discuss the notion of special Kaehler structure and some of its links to complex algebraic geometry, in particular, complex Lagrangians, variations of Hodge structures and algebraic integrable systems. The sequence will conclude with examples related to various moduli spaces of Higgs bundles on curves. For more information please visit the site of the ICMS Seminar: https://icms.bg/category/icms-seminar/  

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The ICMS Seminar will meet this Friday, June 6-th, at 14:00, with three lectures by Peter Dalakov, Lyudmil Katzarkov and Ernesto Lupercio from IMI-BAS. The schedule is the following. June 6-th. Room 403 IMI-BAS. 14:00 - 14:50.  Peter Dalakov Special Kaehler Geometry and some applications (Part II) 15:00 - 15:50.  Lyudmil Katzarkov Atoms and Minimal Model Program 16:00 - 16:50. Ernesto Lupercio Elliptic genus and applications Abstracts and more information can be found at https://icms.bg/category/icms-seminar/

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The ICMS seminar continues with a series of four lectures by Dr. Petеr Dalakov, as follows: Dates: June 3rd, 6th, 10th, 13th, 2:00 pm Place: Room 403, ИМИ-БАН Speaker: Peter Dalakov (IMI and AUBG) Topic: Special Kaehler Geometry and some applications Abstract: In this short sequence of lectures we will discuss the notion of special Kaehler structure and some of its links to complex algebraic geometry, in particular, complex Lagrangians, variations of Hodge structures and algebraic integrable systems. The sequence will conclude with examples related to various moduli spaces of Higgs bundles on curves. For more information please visit the site of the ICMS Seminar: https://icms.bg/category/icms-seminar/  

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The ICMS seminar continues with a series of four lectures by Dr. Petеr Dalakov, as follows: Dates: June 13th, 2:00 pm Place: Room 403, ИМИ-БАН 14:00 – 15:30.  Peter Dalakov Special Kaehler geometry and some applications (Part IV) 16:00 – 17:00. Ernesto Lupercio Elliptic genera and the geometry of loop spaces and applications Abstracts and more information can be found at: https://icms.bg/category/icms-seminar/  

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the ICMS Seminar will be on Friday, with lectures by Alexander Stokolos and Ernesto Lupercio. ICMS Seminar Friday, June 20-th. Room 403 IMI-BAS. 15:30 - 16:30.  Alexander Stokolos (Georgia Southern University) On extremal polynomials Abstract: I will present known and new polynomials emerging from the extremal problems of geometric complex analysis. 16:45 - 17:45. Ernesto Lupercio (IMI-BAS and Cinvestav IPN México) Analysis in Loop Spaces and Genera Abstract: Analysis on loop spaces, motivated by ideas from conformal field theory, leads naturally to the construction of elliptic genera—topological invariants with deep modular and representation-theoretic properties. Мore information can be found at the seminar's website https://icms.bg/category/icms-seminar/

Mathematical Foundations of Informatics Seminar

Veliko Tarnovo University 2, Teodosiy Tarnovski Str., Veliko Tarnovo

The seminar on MATHEMATICAL FOUNDATIONS OF COMPUTER SCIENCE organized by the Department of Mathematical Foundations of Informatics at IMI - BAS and the Faculty of Mathematics and Informatics of Veliko Tarnovo University (VTU), would like to invite you to the next meeting on July 3, 2025 at 2:30 p.m. in room 508, building 4 of VTU. Svetoslava Minkova Master Degree Program in Mathematical Structures in Information Security Faculty of Mathematics and Informatics, Veliko Tarnovo University will deliver a talk on: Weisfeiler-Leman algorithm and graph isomorphism invariants  

ICMS Geometry Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next session of the Geometry Seminar of ICMS will be held on Wednesday, Jully 9th, at 16:00, room 403 and via Zoom: https://icms.bg/around-combinatorial-viros-patchworking-geometry-seminar-talk-by-arthur-renaudineau/ Zoom link: https://us02web.zoom.us/j/86186281353?pwd=6CARUygJaA3HiTNAt3norZQRFt8fIL.1

Joint Seminar of the Analysis, Geometry and Topology Department

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

On July 15, 2025, at 1:00 pm in Room 403 there will be a joint seminar of the Analysis, Geometry and Topology Department and the International Center for Mathematical Sciences – Sofia (ICMS-Sofia). A talk on: Weak Metric Structures on Generalized Riemannian Manifolds will be delivered by Milan Zlatanovic, University of Niš, Serbia. Abstract. Linear connections with torsion are important in the study of generalized Riemannian manifolds (M , G=g+F ), where the symmetric part g of G is a non-degenerate (0,2)-tensor and F is the skew-symmetric part. Some space-time models in theoretical physics are based on (M, G=g+F) , where F is defined using a complex structure. In the lecture, we will show more general models, where F [...]

Joint Seminar of the Analysis, Geometry and Topology Department

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

A joint meeting of the ICMS Seminar and the seminar "Analysis, geometry and topology" at IMI-BAS will be held next Tuesday, with a talk by Elia Fusi. The details are as follows. Tuesday, July 22-nd, 1:00 pm, room 403 of IMI-BAS. Elia Fusi, University of Torino. Special metrics in hypercomplex geometry Abstract:The existence of special hyperHermitian metrics plays an important role in the study of hypercomplex manifolds. In this talk, after a brief overview of the basic definitions in hypercomplex Geometry, we will discuss two of the main types of special metrics in the hypercomplex setting: quaternionic Gauduchon and strong HKT metrics. First of all, we will discuss sufficient and equivalent conditions for a quaternionic Gauduchon metric to exist.  Afterwards, we will show that strong [...]

Joint Seminar of the Analysis, Geometry and Topology Department

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Seminar "Analysis, geometry and topology" Tuesday, July 22-nd, 13:00 o'clock, room 403 of IMI-BAS. Elia Fusi, University of Torino. Special metrics in hypercomplex geometry Abstract: The existence of special hyperHermitian metrics plays an important role in the study of hypercomplex manifolds. In this talk, after a brief overview of the basic definitions in hypercomplex Geometry, we will discuss two of the main types of special metrics in the hypercomplex setting: quaternionic Gauduchon and strong HKT metrics. First of all, we will discuss sufficient and equivalent conditions for a quaternionic Gauduchon metric to exist.  Afterwards, we will show that strong HKT and balanced hyperHermitian metrics cannot coexist on a compact non-hyperKähler manifold, proving a particular instance of the Fino-Vezzoni conjecture. Finally, we will introduce an Einstein [...]

Mathematical Foundations of Informatics Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the seminar of department MATHEMATICAL FOUNDATIONS OF INFORMATICS will be held on July 24, 2025, at 2:00 p.m. in room 403. Prof. Mark Iwen will deliver a talk on: Sparse Spectral Methods for Solving High-Dimensional and Multiscale Elliptic PDEs Prof. Iwen is part of the Department of Computational Mathematics of Michigan State University. His research interests include mathematical data science, signal processing and others. The talk will include some unexpected connections to certain error-correcting codes. Abstract. In his monograph "Chebyshev and Fourier Spectral Methods", John Boyd claimed that, regarding Fourier spectral methods for solving differential equations, "[t]he virtues of the Fast Fourier Transform will continue to improve as the relentless march to larger and larger [bandwidths] continues" [1, pg. 194]. This [...]

Algebra and Logic Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Algebra and Logic Seminar will be held on July 25, 2025 (Friday) at 1:00 pm (UTC+3) in Room 578 of IMI-BAS. A talk on: Distinctness of the “lifted” Kloosterman sums over the prime field Fp will be delivered by Lyubomir Borissov (IMI - BAS). Abstract Everybody is invited. Algebra and Logic Department, IMI - BAS http://www.math.bas.bg/algebra/seminarAiL/ ============================== =====================

Joint Seminar of the Analysis, Geometry and Topology Department

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Seminar "Analysis, geometry and topology" Tuesday, July 29-th, 1:00 pm, room 403 of IMI-BAS. Speaker: Asia Mainenti, IMI and ICMS, Sofia Hodge-Riemann balanced structures on non-Kähler manifolds Abstract: A Hodge-Riemann balanced structure on a complex manifold is the datum of a balanced metric whose (n-1)-th power can be decomposed into the wedge product of two differential forms, satisfying the classical Hodge-Riemann bilinear relations. Such structures were introduced by X. Chen and R. Wentworth, to generalize the nonabelian Hodge correspondence to non-Kähler Hermitian metrics. However, there are no known examples of Hodge-Riemann balanced structures on non-Kähler manifolds. The aim of this talk is to address this lack of examples, highlighting the relation with p-Kähler structures and discuss some obstruction results in the class of solvmanifolds. Lastly, [...]

ICMS Geometry Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next session of the Geometry Seminar of ICMS will be held on Wednesday, August 20th, at 16:00, room 403 and via Zoom: https://icms.bg/friezes-geometry-seminar-talk-by-andrei-zabolotskii/ Zoom link: https://us02web.zoom.us/j/86186281353?pwd=6CARUygJaA3HiTNAt3norZQRFt8fIL.1

ICMS Workshop: Recent Developments on Tropical Sandpiles and Related Subjects

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The International Center for Mathematical Sciences – Sofia (ICMS-Sofia) presents Recent Developments on Tropical Sandpiles and Related Subjects Tuesday, 23 September and Thursday, 25 September 2025 ICMS-Sofia, Room 403 and via Zoom You may find the details here: https://icms.bg/recent-developments-on-tropical-sandpiles-and-related-subjects/ In addition, we plan to have a “round table” meeting at room 378 on Wednesday, September 24, at 14:00, to openly exchange ideas while enjoying drinks and snacks.

ICMS Workshop: Recent Developments on Tropical Sandpiles and Related Subjects

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The International Center for Mathematical Sciences – Sofia (ICMS-Sofia) presents Recent Developments on Tropical Sandpiles and Related Subjects Tuesday, 23 September and Thursday, 25 September 2025 ICMS-Sofia, Room 403 and via Zoom You may find the details here: https://icms.bg/recent-developments-on-tropical-sandpiles-and-related-subjects/ In addition, we plan to have a “round table” meeting at room 378 on Wednesday, September 24, at 14:00, to openly exchange ideas while enjoying drinks and snacks.

Joint Seminar of the AGT Department and ICMS

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Joint Seminar of Analysis, Geometry and Topology Department and International Center for Mathematical Sciences – Sofia (ICMS-Sofia) Concircularly Semi-Symmetric Metric Connection Miroslav Maksimović University of Priština in Kosovska Mitrovica, Kosovska Mitrovica, Serbia, and Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, Bulgaria September 30, 2025, 11:00 h – room 403 Abstract. A concircularly semi-symmetric metric connection is a special class of semi-symmetric metric connection when its generator is a concircular vector. In this talk, we will present results on this connection on pseudo-Riemannian manifolds, and in particular, we will observe the application to Lorentzian manifolds and the theory of relativity. We demonstrate that a Lorentzian manifold reduces to a GRW space-time when the generator of the observed connection is a unit timelike vector. [...]

Algebra and Logic Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Algebra and Logic Seminar will take place in hybrid form on October 3, 2025 (Friday) at 1:00 pm (UTC+3) in Room 578 of IMI-BAS and online via Zoom. A talk on: Decomposition of Tschirnhausen Modules for Coverings on Decomposable P1-Bundles will be delivered by Hristo Iliev (American University in Bulgaria and IMI-BAS). Abstract Link to the zoom meeting: Https://us02web.zoom.us/j/85137375021?pwd=RE5QczdFTE1xL1R6MnI2b1lkcGczQT09 Everybody is invited. Algebra and Logic Department, IMI - BAS http://www.math.bas.bg/algebra/seminarAiL/ ============================== =====================

Joint meeting of the Algebra and Logic Seminar and the Seminar of the Department of Differential Equations and Mathematical Physics

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

A joint meeting of the the Algebra and Logic Seminar and the Seminar of the Department of Differential Equations and Mathematical Physics will be held on October 10, 2025, (Friday), at 1:00 pm in Room 578 of IMI - BAS and online via Zoom. A talk on On Z5 reduction of soliton equations related to sl(5) algebra  will be delivered by Vladimir Gerdjikov (IMI-BAS). This is joint work with B. Kostadinov (IMI-BAS), S. Mishev (NBU), and A. Stefanov (FMU-SU). Abstract: Recently a new approach to the integrable systems, extending and generalizing the ISM was formulated. It is based on an effective parametrization of the Riemann-Hilbert problem, which allows one to extend the class of Lax pairs and effectively derive only the corresponding NLEE as compatibility condition [...]

Applied Mathematics Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Applied Mathematics Seminar will be held on October 15, 2025 (Wednesday) at 3:00 pm in Room 503 of IMI - BAS. A talk on Stochastic scattering control of Walsh's spider diffusion with optimal diffraction probability measure selected from its own local-time will be delivered by Isaac Ohavi, who is working in fields such as stochastic control, stochastic optimization, and partial differential equations. Abstract: In this talk, we start by giving a short introduction on "classical" stochastic control theory and its connection with second order nonlinear PDE theory. Then, we present Walsh’s spider diffusions living on a star-shaped network, and explain how these processes are at the origin of new problems of stochastic scattering control. A main direction is to focus and understand [...]

Singularities Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Date and time: October 20, 2025, 2:00 pm Place: Room 578, IMI - BAS Title: The complete intersection discrepancy of curves Lecturer: Andrei Bengus-Lasnier (ИМИ - БАН) Abstract: In this talk I will introduce an invariant for reduced curves called the complete intersection discrepancy (cid for short). This numerical quantity arose naturally when trying to generalize known formulas for complete intersection curves to general curves. The cid then serves as a correction term in these formulas. I will present some of the cid's basic properties and derive two formulas. The first relates basic invariants such as Milnor number, its multiplicity and the multiplicity of its Jacobian ideal, and generalizes a well-known result in singularity theory due to Lê, Greuel and Teissier. The second formula [...]

Singularities Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Date and time: October 27, 2025, 2:00 pm Speaker:  Erik Paemurru (IMI-BAS) Title: Log canonical thresholds of reduced plane curves Abstract: I will give an overview of normal forms of plane curve singularities and define the log canonical threshold. I will then compute log canonical thresholds of all reduced plane curve singularities of degree at most five and all reduced plane curve singularities of degree d and multiplicity d-1. This is based on the works https://arxiv.org/abs/2404.18238 and https://arxiv.org/abs/2508.21676

National Seminar on Probability and Statistics

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the National Seminar on Probability and Statistics will be held on November 4, 2025, at 2:00 p.m. in Room 503 of the Institute of Mathematics and Informatics. A talk on: On the optimal prediction of extreme events will be delivered by Stilian Stoev (University of Michigan). Abstract  

Atom Theory Research Group Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Seminar Details Speaker: Ludmil Katzarkov (ICMS, IMI-BAS, University of Miami) Title: Recent Advancements in the Theory of Atoms Date & Time: Tuesday, November 4, 2025, at 3:00 PM Place (In-Person): Room 403, IMI-BAS Online Attendance (Zoom) Zoom Link: https://us02web.zoom.us/j/86497450517?pwd=39OtfySJ4SbhKihr1IpaIz32dD7iBp.1 Meeting ID: 864 9745 0517 Passcode: 181023 For further information, always keep track of our website: https://icms.bg/research-groups/theory-of-atoms/

ICMS Geometry Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next session of the Geometry Seminar of ICMS will be held on Wednesday, November 5th, at 14:00, room 403 and via Zoom. A talk entitled Special Linear Systems on Real Algebraic Curves will be delivered by Turgay Akyar (IMI-BAS) More details can be found here: https://icms.bg/special-linear-systems-on-real-algebraic-curves-geometry-seminar-talk-by-turgay-akyar/ Zoom link: https://us02web.zoom.us/j/86186281353?pwd=6CARUygJaA3HiTNAt3norZQRFt8fIL.1

Applied Mathematics Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Applied Mathematics Seminar will be held on November 11, 2025 at 2:00 pm in Room 503 of IMI - BAS. A talk on The number of cycles in a random permutation and the number of segregating sites jointly converge to the Brownian sheet will be delivered by Helmut Pitters (Mannheim, Germany). Abstract: Consider a random permutation of {1, …, ⌊nᵗ²⌋} drawn according to the Ewens measure with parameter t₁, and let K(n, t) denote the number of its cycles, where t ≡ (t₁, t₂) ∈ [0, 1]². Next, consider a sample drawn from a large, neutral population of haploid individuals subject to mutation under the infinitely many sites model of Kimura, whose genealogy is governed by Kingman’s coalescent. Let S(n, t) count the number of segregating sites in [...]

ICMS Geometry Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next session of the Geometry Seminar of ICMS will be held on Wednesday, November 12th, at 14:00, room 403 and via Zoom. A talk entitled Tropical curves with applications will be delivered by Peter Petrov (IMI-BAS) More details can be found here: https://icms.bg/tropical-curves-with-applications-geometry-seminar-talk-by-petar-petrov/ Zoom link: https://us02web.zoom.us/j/86186281353?pwd=6CARUygJaA3HiTNAt3norZQRFt8fIL.1

ICMS Geometry Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next session of the Geometry Seminar of ICMS will be held on Wednesday, November 19th, at 14:00, room 403 and via Zoom. A talk on Tropical curves with applications will be delivered by Peter Petrov (IMI-BAS) More details can be found here: https://icms.bg/tropical-curves-with-applications-geometry-seminar-talk-by-petar-petrov/ Zoom link: https://us02web.zoom.us/j/86186281353?pwd=6CARUygJaA3HiTNAt3norZQRFt8fIL.1

National Mathematics Colloquium

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

UNION OF BULGARIAN MATHEMATICIANS INSTITUTE OF MATHEMATICS AND INFORMATICS, BULGARIAN ACADEMY OF SCIENCES NATIONAL MATHEMATICS COLLOQUIUM The next meeting of the National Mathematics Colloquium will be held on November 20, 2025 (Wednesday) at 4:15 pm EET (UTC +2) in the Conference Room of IMI - BAS. A talk on: Birkhoff Interpolation Problem: Some Old and New Results will be delivered by Prof. Geno Nikolov, Faculty of Mathematics and Informatics, Sofia University. Abstract. In 1906 George David Birkhoff formulated a general interpolation problem for algebraic polynomials (hereafter called BIP). BIP is defined in terms of incidence matrices and encompasses as particular cases the classical Lagrange and Hermite interpolation problems. In contrast with the classical cases, the general BIP is not always solvable. Despite studied by [...]

Seminar of the Mathematical Modeling and Numerical Analysis Department

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Date and time: November 24, 2025, 2:00 pm Place: Room 503, Institute of Mathematics and Informatics Title: Modelling financial crisis propagation as an epidemic on multiplex networks Lecturer: Dr. Malvina Bozhidarova (Russell Group Limited) Abstrac: We propose a novel framework for modelling the spread of financial crises in complex networks, combining financial data, Extreme Value Theory and an epidemiological transmission model. We accommodate two key aspects of contagion modelling: fundamentals-based contagion, where the transmission is due to direct financial linkages, and pure contagion, where a crisis might trigger additional crises due to global effects. We use stock price, geographical location and economic sector data for a set of companies to construct multiplex networks of four layers, on which a Susceptible-Infected-Recovered transmission model is defined, [...]

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Tuesday, November 25-th, 13:00, room 403, IMI-BAS. Deepanshu Prasad (ICMS, IMI-BAS) An Extension of Sato-Kimura Theorem for Semi-invariant rings Abstract:  We give an analog of a result of Sato-Kimura in the context of a semi-invariant  ring for a finite dimensional algebra over an algebraically closed field K of characteristics 0. Then, we examine the case of finite dimensional hereditary algebras over K. This is joint work with Charles Paquette and David Wehlau. https://icms.bg/an-extension-of-sato-kimura-theorem-for-semi-invariant-rings-icms-seminar-talk-by-deepanshu-prasad/

Joint meeting of the ICMS seminar and the seminar on Mathematical Foundations of Informatics

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Wednesday, November 26-th, 16:00, room 403, IMI-BAS Joint meeting of the ICMS seminar and the seminar on Mathematical Foundations of Informatics Frank Vallentin (Universität zu Köln) Least distortion Euclidean embeddings of flat tori Abstract: In the emerging field of bi-Lipschitz invariant theory, one studies embeddings of orbit spaces H/G (H a Hilbert space, G a subgroup of its automorphisms) into simpler Hilbert spaces via distance-preserving maps up to a constant factor. In this talk, I present an infinite-dimensional semidefinite program that computes least-distortion embeddings of flat tori Rn/L, where L is an n-dimensional lattice, into Hilbert spaces. Using symmetry reduction techniques, this infinite-dimensional semidefinite program reduces to an infinite-dimensional linear program. Even with this simplification, solving the program remains challenging. By combining this approach with [...]

ICMS Seminar and Joint Meeting with the Analysis, Geometry and Topology Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next session of the ICMS seminar will take place on Tuesday, December 2, 2025. Talks will be delivered by Roy Magen from ICMS and Liviu Ornea from the University of Bucharest, with the second talk being presented within a joint session with the seminar of the Analysis, Geometry and Topology Department. The program is as follows. ICMS Seminar and AGT Seminar Tuesday, December 2nd, room 403 IMI-BAS. 13:00 -- Roy Magen (ICMS, IMI-BAS) Flavours of homotopy theory 14:00 -- Liviu Ornea (University of Bucarest) Distinguished non-Kähler metrics on compact complex manifolds Abstract (Magen): In this talk we will consider different flavours of homotopy theory for different types of geometric contexts. First we will recall the usual definitions of the homotopy category, and equivariant [...]

ICMS Geometry Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

It is a great pleasure to announce a talk entitled SL2 tropicalizations through valuation algebra by Andrei Benguş-Lasnier (IMI-BAS) who will speak at the Geometry Seminar of ICMS on next Wednesday (3rd of December) at 14:00 in room 403 and via zoom. More details can be found here: https://icms.bg/sl2-tropicalizations-through-valuation-algebra-geometry-seminar-talk-by-andrei-bengus-lasnier/ Zoom link: https://us02web.zoom.us/j/86186281353?pwd=6CARUygJaA3HiTNAt3norZQRFt8fIL.1

Algebra and Logic Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Algebra and Logic Seminar will take place in hybrid form on December 5, 2025 (Friday) at 1:00 pm (UTC+3) in Room 578 of IMI-BAS and online via Zoom. A talk on: Classical Results in ITL with the Neighbourhood Modalities and Their Short Proofs Using Separation will be delivered by Dimitar Guelev (IMI-BAS). Link to the zoom meeting: Https://us02web.zoom.us/j/85137375021?pwd=RE5QczdFTE1xL1R6MnI2b1lkcGczQT09 Everybody is invited. Algebra and Logic Department, IMI - BAS http://www.math.bas.bg/algebra/seminarAiL/ ============================== =====================

Seminar in Operations Research, Probability and Statistics

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

On December 09, 2025 (Tuesday) at 14:15 in room 503 of IMI-BAS and online via Zoom Dr. Sebastian Tapia Garcia, research unit Variational Analysis, Dynamics and Operations Research, Vienna University of Technology will give a talk at the Operations Research, Probability and Statistics Seminar on: Differentiable functions with surjective generalized Jacobians. Abstract: In this talk we start with a brief discussion about the possible values that the limiting and Clarke Jacobians can take in the class of differentiable locally Lipschitz functions (defined on finite dimensional spaces). Then, we construct a differentiable locally Lipschitz function f:R^n\to R^m such that, for any nonempty compact connected C \subset R^{n х m} , we can find a point x in R^n such that C coincides [...]

Applied Mathematics Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

The next meeting of the Applied Mathematics Seminar will be held on December 10 (Wednesday) at 3:00 PM in room 503 of IMI-BAS. Lecturer: Giuseppe D'Onofrio (Politecnico di Torino, Италия) Title: ADDITIVE SUBORDINATION OF MULTIPARAMETER MARKOV PROCESSES Abstract: In this talk, we consider multiparameter multidimensional Markov processes that are time-changed by an independent additive subordinator, obtained from a Lévy process by relaxing the condition of stationary increments. By extending Phillips theorem, we show that the resulting process is a Feller evolution and we characterize its generator. We further derive its pseudo-differential representation and show that its symbol admits a Lévy-Khintchine representation. As an application, we consider a factor-based specification for the Ornstein-Uhlenbeck process subordinated by a Sato process. The constructive nature of this process [...]

Singularities Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Time and place: January 12, 2026, Monday, at 2:00 pm, in Room 578, Institute of Mathematics and Informatics - Bulgarian Academy of Sciences Lecturer:  Valdemar Tsanov (IMI-BAS) Title: Geometry of Milnor fibrations of equivariant plane curves Abstract: The local knot of an irreducible C*-equivariant complex plane curve singularity is a torus knot, and the Milnor fiber is a Seifert surface for this knot. I will describe an explicit universal cover of the Milnor fiber by the hyperbolic plane, using automorphic forms for triangle groups. The characteristic morphism of the Milnor fibration can also be recovered, and used to construct geometric structures by universal covers on the knot complement in the 3-sphere, as well as on the complement of the singular curve in the complex plane.

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Time and place: Tuesday, January 20th, 2026, 1:00 pm, room 403 IMI-BAS. Lecturer: Bogdan Đorđević (Serbian Academy of Arts and Sciences) Title: Applications of Banach algebras and Banach modules to some contemporary analysis problems Abstract: In recent years applied mathematics has experienced a historical progress, blurring the lines between the previously clear research paths and directions. Accordingly, contemporary mathematical analysis is at the verge of unifying seemingly different research areas and topics. With this in mind, I'd like to talk about my humble contribution to this cause: my lecture will concern how Banach algebras and modules, combined with spectral theory, functional calculus, and generalized inverses, help in various problems that emerge in applied mathematics in general: from solving operator and matrix equations, to evaluating sums [...]

ICMS Seminar

Institute of Mathematics and Informatics, BAS Akad.G.Bonchev St, bl. 8, 1113, Sofia

Time and place: Tuesday, January 27th, 2026, 1:00 pm, room 403 IMI-BAS. Lecturer: Jean-Pierre Gazeau (Université Paris Cité, CNRS, and University of Białystok) Title: Spectral and angular variables for open qudit dynamics Abstract:  In this talk, I introduce a parametrization of finite-dimensional quantum states that is particularly adapted to the study of open qudit dynamics. Any generic density matrix in Cn can be described by separating spectral variables, which encode the eigenvalue content, from angular variables associated with the unitary degrees of freedom. These angular variables naturally live on the coset space SU(n)/T, in the spirit of the Tilma–Sudarshan construction. A key outcome of this parametrization is a partial decoupling of the GKLS evolution: while the angular variables are driven by both the Hamiltonian and [...]

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