Latest Past Events

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. [...]

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: [...]

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 [...]

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