Applied Mathematics Seminar

Temporal networks, Tensors, and applications to ML Speaker: Prof. Ognyan Kounchev Date: January 31, 2024 Time: 3:00 pm Place: ... Abstract: 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 brings a [...]

Applied Mathematics Seminar

How log-concavity fought lottery frauds in Florida and what it did after winning Speaker: Dmitri Karp Date: November 14, 2023 Time: 2:00 pm Place: Room 503 of IMI - BAS Abstract: In the talk I will first discuss the log-concavity in parameters of the normalized beta function (which represents the cumulative distribution function of beta distributed random variable) that has been used recently in an investigation of lottery frauds in Florida.  I will then present some related  properties of incomplete beta function and proceed to general log-concavity problems and their particular cases motivated by various problems in statistics, probability and analysis. Facebook page of the seminar: Семинар по Приложна математика

Applied Mathematics Seminar

Finite automata and neural networks for language modeling Speaker: Prof. Stoyan Mihov Date: October 25, 2023 Time: 3:00 pm Place: Room 503 of IMI - BAS Facebook page of the seminar: Семинар по Приложна математика

Prof. Bernard Teissier is visiting the International Center for Mathematical Sciences – Sofia

Prof. Bernard Teissier is a world-renowned mathematician who works in the field of algebraic geometry, singularity theory and commutative algebra. Prof. Teissier is a guest of the program "Increasing research capacity in the field of mathematical sciences" (PIKOM) of the Institute of Mathematics and Informatics at the Bulgarian Academy of Sciences (IMI–BAS) and the International Center for Mathematical Sciences - Sofia (ICMS-Sofia).

Seminar of the International Center of Mathematical Sciences

The next meeting of the seminar of the International Center for Mathematical Sciences will be held on Tuesday, June 6, 2023, at 3:00 pm, in Room 403 of IMI - BAS. Speaker: Hussein Mourtada (Institut de Mathématiques de Jussieu-Paris Rive Gauche). Title: Arc spaces and partition identities Abstract

Applied Mathematics Seminar

NUMERICAL SOLUTION OF MULTIDIMENSIONAL SPECTRAL FRACTIONAL DIFFUSION PROBLEMS: FROM CAFFARELLI TO BURA Authors: Bálint Farkas, Béla Nagy and Szilárd Révész, Alfréd Rényi Institute of Mathematics Date: June 6, 2023 Time: 5:30 pm Place: Room 503 of IMI - BAS Abstract: We introduce a general framework to investigate minimax problems for sum of translates functions F(x,t)=\sum_k K(t-x_j) or F(x,t)=J(t)+\sum_k K(t-x_j), where K is a general concave "kernel function" and J is an "outer field" function, t runs [0,1], and x=(x_1,...,x_n) is a set of nodes which are used to translate the kernel. Our setup is very close to logarithmic potential theory, but fixing n and focusing on a more detailed analysis, we obtain new results even for very classical problems. Extending a method of P. Fenton, we reach considerable [...]

Applied Mathematics Seminar

NUMERICAL SOLUTION OF MULTIDIMENSIONAL SPECTRAL FRACTIONAL DIFFUSION PROBLEMS: FROM CAFFARELLI TO BURA Lecturer: Prof. Sv. Margenov (IICT - BAS) Time: 3:00 pm Date: May 23, 2023 Place: Room 503 of IMI - BAS Abstract: Fractional diffusion operators appear naturally in many areas in mathematics, physics, ect. The most important property of the related b.v. problems is that they are nonlocal. Let us consider the fractional power of a self-adjoint elliptic operator introduced through its spectral decomposition. It is also self-adjoint but nonlocal. Advanced numerical methods in this area have been heavily influenced by the pioneering work in differential operator theory by Caffarelli and Silvestre, "An Extension Problem Associated with the Fractional Laplacian", 2007. After discretization, nonlocal problems lead to linear systems with dense matrices. In the [...]

Seminar of the International Center of Mathematical Sciences

The next meeting of the seminar of the International Center for Mathematical Sciences will be held on Tuesday, March 14, 2023, at 2:00 pm, in Room 403 of IMI - BAS. Speaker: Dr. Jiachang Xu, IMI - BAS. Title: Non-Archimedean Uniformization and its application Abstract

Joint seminar of the ICMS and the MFI Department

A joint seminar of the International Center for Mathematical Sciences and the Department of Mathematical Foundations of Informatics will be held on Tuesday, March 7, 2023, at 2:00 pm, in Room 403 of IMI - BAS. Speaker: Dr. Alexandr Polyanskii, IMI - BAS. Title: Plank Problems: Discrete Geometry and Convexity Abstract: The set of points lying between two parallel lines in the plane is called a plank. Given a convex region C in the plane, what is the smallest combined width of a finite collection of planks that cover C? What happens in higher dimensions? In the 50s, Thoger Bang answered this innocent question of Alfred Tarski and opened a box with many deceptively simple-looking problems. In my talk, I will overview progress in the [...]

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