【报告信息】
报告1：
报告题目：Minimal polynomials of elements in projective representations of the symmetric group
报告人：A. Staroletov (Sobolev Institute of Mathematics)
报告时间：2026-10-14 14:00-14:50
报告地点：Zhihua Building 209
报告摘要：The talk will discuss the description of the minimal polynomials of elements of the symmetric and alternating groups in all projective representations over the field of complex numbers.
报告2：
报告题目：Stack Algebras: Simplicity and Nilpotency
报告人：Artem Lopatin (UNICAMP)
报告时间：2026-10-14 15:00-15:50
报告地点：Zhihua Building 209
报告摘要：We introduce and study the variety of stack algebras, defined by the identity [x(yz) = \lambda (xy)z + \mu (xz)y. ]
Several families of examples are constructed, including matrix-type examples, and all two-dimensional stack algebras are classified. A key structural result shows that every nonassociative word in a stack algebra can be expressed as a linear combination of left-normed words. This leads to general results on nilpotency, including bounds for the nilpotency degree, a description of null-filiform stack algebras, and parameter conditions implying the identity A^4=0.
We also classify finite-dimensional simple stack algebras over an arbitrary field: every such algebra is classically simple, namely, either a simple associative algebra or a simple Lie algebra. In particular, there are no finite-dimensional nonclassically simple stack algebras. Finally, we compare the variety of stack algebras with several classical varieties of nonassociative algebras, including alternative, noncommutative Jordan, and Novikov algebras.
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【报告信息】
报告题目：The sets of element orders of almost simple groups of Lie type
报告人：Maria Grechkoseeva (Sobolev Institute of Mathematics)
报告时间：2026-09-01 14:30-15:30
报告地点：Zhihua Building 413
报告摘要：
The problem of recognition of finite simple groups by element orders gave rise to the following Problem 1: for every finite simple group $L$ of Lie type and every $G$ such that $L\leq G\leq Aut L$, find the set of element orders of $G$.
By Steinberg's theorem, every automorphism of a simple group of Lie type is a product of inner, diagonal, field and graph automorphisms. By Shintani descent, Problem 1 can be reduced to Problem 2: for every finite simple group $L$ of Lie type and every automorphism $\alpha$ of $L$, which is a product of inner, diagonal and graph automorphisms, find the set of orders of elements in the coset $L\alpha$. I will talk about the reduction of Problem 1 to Problem 2 and what is known on Problem 2.
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【报告信息】
报告1：
报告题目：Groups with restrictions on the set of conjugacy classes sizes
报告人：Ilya Gorshkov (Sobolev Institute of Mathematics, Novosibirsk, Russia)
报告时间：2026-05-20 14:30-15:20
报告摘要：
This talk is devoted to the problem of reconstructing the structure of a finite group from its invariant $N(G)$—the set of conjugacy classes sizes. We will consider questions about how uniquely this set of numbers determines the group, especially in the class of groups with trivial center. The main topics of the talk are:
1. Graph Methods: Introduction and use of various graphs on the set $N(G)$ for group structure analysis, such as the divisibility graph and the prime graph.
2. Special Classes of Groups: Investigation of the properties of $CH$-groups and $SP$-groups.
3. Nilpotency Problem: We discuss Camina's conjecture on whether the nilpotency of a group $G$ follows from the coincidence of its $N(G)$ with $N(H)$, where $H$ is a nilpotent group.
报告2：
报告题目：Recognition of finite simple groups by element orders
报告人：Maria Grechkoseeva (Sobolev Institute of Mathematics, Novosibirsk, Russia)
报告时间：2026-05-20 15:30 -16:20
报告摘要：
Given a finite nonabelian simple group $L$, what can we say about the structure of a finite group $G$ having the same set of element orders as $L$? By 2013, the question has been solved for alternating and sporadic groups, and the result is that $G$ is isomorphic to $L$ unless $L$ is one of three exceptions. By 2015, it has been solved for exceptional groups of Lie type, and the result is that $G$ is an almost simple group with socle isomorphic to $L$, with one exception. This year, we have completed the case of classical groups, and the main goal of this talk is to present the solution and explain the key ideas of the proof.
【线下活动教室】
智华楼413号教室
【线上ZOOM会议链接】
会议链接：https://us02web.zoom.us/j/83690328797?pwd=am1JjwGhpqzYy8Z2Lcct21uqfwuiAw.1
会议号: 836-9032-8797 ，密码: 340130
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【报告信息】
报告主持人：张继平老师
报告题目：Arithmetic invariants for finite simple and related groups
报告人：Andrey V. Vasil'ev (Sobolev Institute of Mathematics, Novosibirsk, Russia)
报告时间：14:30-15:30
报告摘要：
Abstract: Like primes in number theory, simple groups lie in the core of finite group theory. The same remains true for groups closely related to simple groups: almost simple, quasisimple and so on. Attempts to characterize such groups in the class of all finite groups in one way or another have been made many times and became especially persistent since the classification theorem was announced and the complete list of simple groups became available. In this talk we address the problems of characterization of simple and related groups by various arithmetic invariants. We come with some uniform way to think about such sort of problems and discuss what has been already done and what we still do not know but wish to know in this field.
【线下活动教室】
智华楼413号教室
【线上ZOOM会议链接】
会议开始时间：2026年4月15日 02:00 下午
会议链接：https://us02web.zoom.us/j/83690328797?pwd=am1JjwGhpqzYy8Z2Lcct21uqfwuiAw.1
会议号: 836-9032-8797
密码: 340130
