The next meeting of the Algebra and Logic Seminar will be held in hybrod format (in Room 578 of IMI - BAS and online via Zoom) on December 1, 2023 (Friday) at 1:00 pm (UTC+2). A talk on: Characterization of Ideals of Q-algebras Related to its G-part will be delivered by Jörg Koppitz (IMI - BAS, Bulgaria). Abstract. In this presentation, we study the G -part of Q -algebras X , i.e. the set G(X)=\{x\in X:0x=x\} . We show that G(X) is an abelian group, whenever G(X) is an ideal and characterize all Q -algebras X such that G(X) is an ideal of X . Moreover, we show that, up to isomorphism, there is only one Q -algebra X with G(X)=X , [...]

The next meeting of the Algebra and Logic Seminar will be held online on November 24, 2023 (Friday) at 1:00 pm (UTC+2) with two talks. At 1:00 pm (UTC+2) Dimitrinka Vladeva (IMI - BAS) will deliver a talk on Catalan numbers and additively idempotent semirings At 2:00 pm (UTC+2) Roussanka Loukanova (IMI - BAS) will deliver a talk on Semantics of Propositional Attitudes in Type-Theory of Algorithms Title: Catalan numbers and additively idempotent semirings Abstract. The purpose of the present talk is to provide new applications of remarkable Catalan numbers. In Richard Stanley’s book Enumerative Combinatorics, Volume II (Cambridge University Press) there are many combinatorial objects that are counted by the Catalan numbers as well as applications in graph theory, Young diagrams, lattice theory, real matrices, [...]

The next meeting of the Algebra and Logic Seminar will be held in hybrod format (in Room 578 of IMI - BAS and online via Zoom) on November 17, 2023 (Friday) at 1:00 pm (UTC+2). A talk on: Noncommutative invariants of dihedral groups will be delivered by Boyan Kostadinov (IMI - BAS, Bulgaria). Abstract. We consider the 2-generated free metabelian associative and Lie algebras over the complex field and the invariants of the dihedral groups of finite order acting on these algebras. In the associative case we find a finite set of generators of the algebra of invariants. In the Lie case, when the algebra of invariants is not finitely generated, we give a minimal system of generators of the invariants in the commutator [...]

The next meeting of the Algebra and Logic Seminar will be held in hybrod format (in Room 578 of IMI - BAS and online via Zoom) on November 10, 2023 (Friday) at 1:00 pm (UTC+2). A talk on: Transfinite version of the Mittag-Leffler condition for the vanishing of the derived limit will be delivered by Mishel Carelli (Technion – Israel Institute of Technology, Israel). Abstract.We give a necessary and sufficient condition for an inverse sequence  S0 ← S1 ← . . . indexed by natural numbers to have lim¹S = 0. This condition can be treated as a transfinite version of the Mittag-Leffler condition. We consider inverse sequences in the category of abelian groups. We also show that the class of inverse sequences S [...]

The next meeting of the Algebra and Logic Seminar will be held online via Zoom on November 3, 2023 (Friday) at 1:00 pm (UTC+2). A talk on: A Reduction of Temporary Coalitions in Infinite Multiplayer Games will be delivered by Dimitar Guelev (IMI-BAS, Bulgaria). Abstract.We propose a transformation of Concurrent Game Models which enables the reduction of infinite multiplayer games where players can form temporary coalitions to games with no coalitions by extending moves to include the negotiation steps that lead to the formation of coalitions. We adopt conditional promises as the building blocks of negotiation. Temporary coalitions and their agendas arise as the logical consequences of mutual promises. The transformation enables the use of established solution concepts about games with no coalitions for [...]

The next meeting of the Algebra and Logic Seminar will be held in hybrid format (in Room 578 of IMI and online via Zoom) on October 20, 2023 (Friday) at 1:00 pm (UTC+3). A talk on: Prime numbers and random walks in a square grid will be delivered by Alberto Fraile (Czech Technical University in Prague, Czech Republic). Joint work with Osame Kinouchi, Prashant Dwivedi, Roberto Martínez, Theophanes E. Raptis, and Daniel Fernández Abstract. One can argue that prime numbers present perplexing features, in a hybrid of local unpredictability and global regular behavior. It is this interplay between randomness and regularity that motivated searches for both local and global patterns that could potentially become signatures for certain underlying fundamental mathematical properties.In recent years, computer simulations [...]

The next meeting of the Algebra and Logic Seminar will be held in hybrid format (in Room 578 of IMI and online via Zoom) on October 13, 2023 (Friday) at 1:00 pm (UTC+3). A talk on: Emmy Noether’s Theorem on the Finite Generation of the Algebra of Invariants will be delivered by Marin Genov (Institute of Mathematics and Informatics, Bulgarian Academy of Sciences). Abstract. I will introduce Emmy Noether’s theorem on the finite generation of invariants and give two proofs of it. As an example, I will also calculate the algebra of invariants of the dihedral group of order 2n acting on C[x,y]. Link to the Zoom room: https://us02web.zoom.us/j/85137375021?pwd=RE5QczdFTE1xL1R6MnI2b1lkcGczQT09 Algebra and Logic Department, IMI - BAS http://www.math.bas.bg/algebra/seminarAiL/ ============================== =====================

The next meeting of the Algebra and Logic Seminar will be held online in Zoom on September 29, 2023 (Friday) at 1:00 pm (UTC+2). A talk on: Reset Controller Synthesis will be delivered by Naijun Zhan (Institute of Software Chinese Academy of Sciences (ISCAS), China). Abstract. Controller synthesis provides a Correct-by-construction mechanism to guarantee the correctness and reliability of hybrid systems (HS) by design. Depending on the types of controls, controllers can be classified into reset controllers, feedback controllers, and switching logic controllers. Reset controllers steer the behaviour of a HS to attain system objective through restricting its initial set and redefining the reset map associated with discrete jumps, which is less explored in the literature, although it is of theoretical and practical significance. In this [...]

The next meeting of the Algebra and Logic Seminar will be held on June 23, 2023 (Friday) at 1:00 pm 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 Borisov. Abstract   Algebra and Logic Department, IMI - BAS http://www.math.bas.bg/algebra/seminarAiL/ ============================== =====================