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## June 2019

The next meeting of the National Seminar on Probability and Statistics will be held on .June 26, 2019 (Wednesday), at 3.00 p.m., in Room 403 of the Institute of Mathematics and Informatics, BAS. A talk on Geometric and Geometric-Like Processes: An Overview and Some Applications will be delivered by Stefanka Chukova (Victoria University of Wellington, New Zealand). Everybody is invited. Abstract: In the first part of this talk we introduce the geometric-like processes. The geometric process introduced by Lam (1988) can be used to model the occurrence of events with underlying monotonic trends. This type of trends can be observed in many practical problems in different areas of our everyday life, such as engineering, epidemiology, business, health, etc. In order to provide improved flexibility in [...]

Find out moreOn June 28, 2019, at 11:00 a.m. in Room 478 of IMI, the next meeting of the Differential Equations Seminar will be held. Col. Prof. Chhanda Samanta, Virginia Military Institute, USA, will deliver a lecture on: A GENERALIZED MASS FORMULA FOR STRANGE AND NON-STRANGE NUCLEI Abstract. In 1953 a strange nucleus called “Hypernucleus” was first discovered that contains a hyperon in addition to neutrons and protons. While neutrons and protons are made of up and down quarks, hyperons are made of different combinations of up, down and strange quarks. Since its first discovery, about 50 different strange-nuclei have been found with different “strangeness”. In March 2010, a strange anti-hypernucleus called, anti-hypertriton was discovered at Brookhaven National Laboratory, USA that gave a glimpse of the [...]

Find out moreOn June 28, 2019, at 12:00 a.m. in Room 478 of IMI, the next meeting of the Differential Equations Seminar will be held. Col. Prof. Dimple Chalishajar, Virginia Military Institute, USA, will deliver a lecture on: EXACT AND TRAJECTORY CONTROLLABILITY OF NONLINEAR AND FRACTIONAL ORDER SYSTEMS: A THEORETICAL AND AN ANALYTICAL APPROACH Abstract. Study of nonlinear systems is important since most of the practical systems are nonlinear in nature. There are different notions of controllability like complete controllability, approximate controllability, exact controllability, partial exact controllability, null controllability, local controllability, etc. A current notion of controllability namely Trajectory controllability (T - controllability) has been introduced as a new direction in the field of control theory. We have discussed T- controllability of the first and second [...]

Find out moreThe next meeting of the Algebra and Logic Seminar will be held on June 28, 2019 (Friday) at 1:00 p.m. in Room 578 of the Institute of Mathematics and Informatics. A talk on The approach of intersecting null four-dimensional gravitational cones and a new theory of GPS intersatellite communications between moving satellites in the (near-Earth) gravitational field will be delivered by Bogdan G. Dimitrov (Instutute of Nuclear Research and Nuclear Energy at BAS and Institute of Advanced Physical Studies, New Bulgarian University). Everybody is invited.

Find out more## July 2019

Seminar MATHEMATICAL FOUNDATIONS OF INFORMATICS The next meeting of the seminar will be held on July 4, 2019, at 3.00 p.m. in Room 503 of IMI-BAS. A talk on: Rotation cryptanalysis on Chaskey will be delivered by Liliya Kraleva, Catholic University of Leuven. Abstract. Rotational cryptanalysis is a probabilistic technique mainly used over ARX cryptographic structures. After encryption, if the outputs also form a rotational pair with probability more than for a random permutation we can use that as a distinguisher. Chaskey is a lightweight MAC algorithm for 32-bit microcontrollers. Its underlying block cipher has a permutation using only XOR, rotation and modular addition as operations. We perform a related key attack over Chaskey and find a distinguisher by using rotational probabilities. Having a [...]

Find out moreThe next meeting of the Interdisciplinary Seminar on Biomathematics and Scientific Computing will be held on July 4, 2019 (Thursday), at 3.00 p.m. in Room 403 of IMI-BAS. A talk on: Ergodicity and loss of capacity for a family of concave random maps will be delivered by Prof. Peter Hinow (University of Wisconsin-Milwakee, САЩ) Abstract. Random fluctuations of an environment are common in ecological and economical settings. We consider a family of concave maps on the unit interval, f_λ(x)=x(1+λ-x), that model a self-limiting growth behavior. The maps are parametrized by an independent, identically distributed random variable λ with values in the unit interval. We show the existence of a unique invariant ergodic measure of the resulting random dynamical system for arbitrary parameter distributions supported on [...]

Find out moreThe next meeting of the Seminar on Operations Research will be held on July 9, 2019, at 2 p.m. in Room 403 of IMI. A talk on: On complementary eigenvalue problem will be delivered by A. Iusem, Instituto de Matematika Pura e Aplicada (IMPA), Rio de Janeiro RJ, Brazil. Abstract. We introduce the Complementary Eigenvalue Problem (EiCP), and present basic results on existence and number of solutions. We discuss next som ии e state-of-the-art methods for its solution; namely the spectral gradient method for the symmetric case and the hybrid method (combining a semismooth Newton method with a branch and boundsearch procedure) for the nonsymmetric case. Then we consider three extensions of the problem: The Conic Complementary Eigenvalue Problem (CEiCP), the Quadratic Complementary Eigenvalue [...]

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