Algebra and Logic Seminar

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/ ============================== =====================

2023-10-06T18:42:06+03:00Friday, 6 October 2023|Categories: |Tags: |

Algebra and Logic Seminar

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 [...]

2023-10-06T16:25:16+03:00Monday, 25 September 2023|Categories: |Tags: |

Joint meeting of the Analysis, Geometry and Topology Seminar and the Algebra and Logic Seminar

A joint meeting of the Analysis, Geometry, and Topology Seminar and the Algebra and Logic Seminar will be held on September 26, 2023, at 2:00 pm in Room 478 of IMI - BAS. A talk on Burau Representation and Application to Reducibility and Exchangeability of Braids will be delivered by Alexander Stоimenov, Dongguk University, Republic of Korea. Abstract. I will give an introduction to the braid groups, closure operation, Markov theorem, and exchange move. Then I will introduce the Burau representation, and discuss its application to reducibiliy and exchangeability of braids.

2023-09-18T14:50:27+03:00Sunday, 17 September 2023|Categories: , |Tags: , |

Algebra and Logic Seminar

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/ ============================== =====================

2023-06-20T13:44:05+03:00Tuesday, 20 June 2023|Categories: |Tags: |

Algebra and Logic Seminar

The next meeting of the Algebra and Logic Seminar will be held on June 16, 2023 (Friday) at 1:00 pm (UTC+3) online in Zoom. A talk on: Polynomial identities in Novikov algebras will be delivered by Nurlan Ismailov (Astana IT University and Suleyman Demirel University, Kaskelen, Kazakhstan) (Joint work with V. Dotsenko and U. Umirbaev). Abstract.The talk is devoted to Novikov algebras satisfying nontrivial identities. We show that a Novikov algebra over a field of zero characteristic that satisfies a nontrivial identity satisfies some unexpected “universal” identities, in particular, right associator nilpotence, and right nilpotence of the commutator ideal. This, in particular, implies that a Novikov algebra over a field of zero characteristic satisfies a nontrivial identity if and only if it is Lie-solvable. We [...]

2023-06-12T13:02:35+03:00Monday, 12 June 2023|Categories: |Tags: |

Algebra and Logic Seminar

The next meeting of the Algebra and Logic Seminar will be held on June 9, 2023 (Friday) at 1:00 pm (UTC+3) online in Zoom. A talk on: Old and new aspects of the Poincaré-Birkhoff-Witt theorem will be delivered by Vladimir Dotsenko (Institute for Advanced Mathematical Research (IRMA), University of Strasbourg and CNRS, France). Abstract.The Poincaré-Birkhoff-Witt theorem on universal enveloping algebras of Lie algebras is a fundamental result in many areas of mathematics: from differential geometry and representation theory to homological algebra and deformation quantization. I shall give a short overview of that result and some of its proofs that emerged in about 120 years since Poincaré published a paper about it, and outline a new proof which perhaps captures its category-theoretic essence in the best [...]

2023-06-01T10:16:53+03:00Thursday, 1 June 2023|Categories: |Tags: |

Algebra and Logic Seminar – Inaugural lecture by Prof. J. Kopitz

The next meeting of the Algebra and Logic Seminar will be held on May 5, 2023 (Friday) at 1:00 pm (UTC+3) online in Zoom. Prof. Jörg Koppitz will deliver his inaugural lecture on: Algebraic Properties of Transformation Semigroups Abstract. Each semigroup is isomorphic to a semigroup of transformations on a suitable set (Cayley Theorem for semigroups). If we know generating sets of minimal size (rank) of a finitely generating semigroup then we have important information about the algebraic structure of the semigroup itself. For not finitely generated semigroups, we consider relative generating sets of minimal size modulo a given subset of the semigroup (relative rank). We determine the (relative) rank of several semigroups of transformations. These semigroups were already considered by other authors. By the study [...]

2023-05-02T21:44:37+03:00Tuesday, 2 May 2023|Categories: |Tags: |

Algebra and Logic Seminar

The next meeting of the Algebra and Logic Seminar will be held on April 7, 2023 (Friday) at 1:00 pm (UTC+3) online in Zoom. A talk on: Exact values of exponential Følner functions and the Coulhon and Saloff-Coste inequality will be delivered by Bogdan Stankov (Institut Camille Jordan, Université Claude Bernard Lyon 1, France). Abstract.For infinite groups, the Følner criterion states that a group is amenable if and only if the isoperimetric constant of its Cayley graph is 0. In that case, a more precise description of its isoperimetric profile is given by the Følner function. It depends on the choice of generating set, but different functions on the same group are asymptotically equivalent. Multiple results have been obtained on Følner functions, but only up [...]

2023-04-05T23:16:05+03:00Monday, 3 April 2023|Categories: |Tags: |

Algebra and Logic Seminar

The next meeting of the Algebra and Logic Seminar will be held on February 24, 2023 (Friday) online in Zoom. A talk on: Real Hamiltonian forms of affine Toda field theories: spectral aspects will be delivered by Vladimir Gerdjikov (joint work with G. G. Grahovski and A. A. Stefanov). Abstract. The talk is devoted to real Hamiltonian forms of 2-dimensional Toda field theories related to exceptional simple Lie algebras, and to the spectral theory of the associated Lax operators. Real Hamiltonian forms are a special type of reductions of Hamiltonian systems, similar to real forms of semisimple Lie algebras. The real Hamiltonian forms of affine Toda field theories related to exceptional complex untwisted affine Kac - Moody algebras are studied. Along with the associated Lax [...]

2023-02-20T12:06:56+02:00Monday, 20 February 2023|Categories: |Tags: |

Algebra and Logic Seminar

The next meeting of the Algebra and Logic Seminar will be held on February 17, 2023 (Friday) online in Zoom. A talk on: Invariant theory for reductive subgroups of reductive groups will be delivered by Valdemar Tsanov (IMI-BAS). Abstract.Let H ⸦ G be an embedding of connected complex reductive linear algebraic groups. A classical question with several important interpretations is: which irreducible G-modules contain nonzero H-invariant vectors? An approach based on the Geometric Invariant Theory of Hilbert-Mumford was developed in works of Heckman, Berenstein-Sjamaar, Belkale-Kumar and Ressayre, culminating in a description of the generalized Littlewood-Richadson cone - the convex hull of set of the highest weights of the G-modules containing H-invariants. The discrepancy between the convex hull and the actual set of weights presents [...]

2023-02-14T14:47:57+02:00Tuesday, 14 February 2023|Categories: |Tags: |
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