ÌÇÐÄAPP

Speaker: Yuri A. Bakhturin, ÌÇÐÄAPP
Time/Date: Wednesday, October 21st, 2026, 1 p.m.
Room: HH3017
Title: Spectral sequences in locally finite varieties of algebras

Abstract:
I will talk about numerical characteristics of the sets of identical relations of algebras over finite fields.

Speaker: Tom Baird, ÌÇÐÄAPP
Time/Date: Thursday, October 15th, 2026, 12 p.m.
Room: HH3017
Title: The Cohomology of Sheaves

Abstract:
Sheaves and their cohomology play a fundamental role in algebra, geometry, and topology. In this series of lectures, I will introduce these concepts, develop their theory, and explore applications.
In this first lecture, I will explain what a sheaf is and why is interesting, and then define the cohomology of a sheaf.

Speaker: Serhii Koval, ÌÇÐÄAPP/Saint Mary's University
Time/Date: Wednesday, October 14th, 2026, 1 p.m.
Room: HH3017
Title: Generic graded contractions of Lie algebras

Abstract:
Contractions and degenerations of Lie algebras have been extensively studied since the 1950s. The idea is to pass from one Lie algebra to another by some kind of limit process. Another type of contractions was introduced by de Montigny and Patera (1991) in the context of Lie algebras over a field F equipped with a grading by an abelian group G. In this framework, the Lie bracket of two homogeneous elements is modified by a scalar factor that depends on the degrees of the elements. The resulting scaling function must satisfy specific conditions to ensure that the new bracket remains antisymmetric and satisfies Jacobi identity.
We are interested in generic graded contractions, i.e., those that produce a new Lie bracket for any G-graded Lie algebra. They can be viewed as lax monoidal structures on the identity endofunctor of the category of G-graded vector spaces. We show that generic graded contractions with a fixed support S are classified by a certain abelian group H²_S(F^x), which we explicitly describe. We also analyze which generic graded contractions define graded degenerations of a given G-graded Lie algebra.
This talk is based on a joint work with M. Kochetov.
Kochetov M. and Koval S., Generic graded contractions of Lie algebras,  J. Algebra 696 (2026), 245-277. arXiv:2506.00610.

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Speaker: Daniel Offin, Queen's University
Time/Date: Thursday, October 8th, 2026, 12 p.m.
Room: HH 3017
Title: Dynamics and symmetry: minimizing brake orbits

Abstract:
After Newton proposed his universal laws of motion, there was a lively debate in the 18th c concerning the principle of least action championed by Maupertuis and later Euler and Lagrange. This approach was based on Maupertuis's principle of minimum action. Maupertuis’s principle of least action states that in all natural phenomena a quantity called ’action’ tends to be minimised. We shall give a short history of this principle and its modern formulations culminating in the study of the spectrum of minimizers, bringing together symplectic geometry, dynamcial systems and symmetry groups.