应数学与统计学院徐守军教授邀请，新西兰奥克兰大学数学系Marston Conder教授将于2019年10月17日-10月20日访问我校并作学术报告。

报告1：Symmetry and chirality in discrete structures

时 间：10月17日下午14:30

地 点：榆中校区天山堂B503

摘 要：Symmetry is pervasive in both nature and human culture. The notion of chirality (or 'handedness') is similarly pervasive, but less well understood. In this lecture, which is dedicated to my late colleague Peter Lorimer, I will talk about a number of situations involving discrete objects that have maximum possible symmetry in their class, or maximum possible rotational symmetry while being chiral. Examples include combinatorial graphs (networks), geometric solids, maps on surfaces, and some other more abstract structures. These will be illustrated by pictures as much as possible.

报告2：Some new approaches to finding the minimum genus of a graph

时 间：10月18日上午10:30

地 点：齐云楼911 报告厅

摘要：The genus of a connected graph $X$ is defined as the smallest genus of those compact orientable surfaces into which $X$ has a 2-cell embedding (breaking up the surface into `faces'). For example, planar graphs are precisely those having genus $0$.

In this talk I'll describe some recent work that helps find the minimum genus of certain graphs (also in the non-orientable case), when traditional methods are not helpful. One new method uses the orbits of the automorphism group of the graph on cycles of small length, as candidates for bounding cycles of faces of the embedding.

This turned out to be helpful in finding the small genus embeddings of several graphs of interest, and then in combination with two other new approaches for eliminating smaller genera (using independence numbers and integer linear programming), led to the answers to a many open questions.

欢迎广大师生参加！

报告人简介

Marston Conder院士，是一位国际声望极高的数学家，国际代数图论方向领头人，现任新西兰奥克兰大学杰出教授，新西兰科学院院士。曾任新西兰皇家科学院院长、新西兰皇家学会副主席、新西兰数学会理事长、新西兰数学及应用研究所所长，奥克兰大学副校长、代数领域顶级期编委。2014年获新西兰最高科学奖，即皇家学会。已发表SCI论文120余篇，其中多篇发表在数学领域顶级期刊，被SCI引用700余次，平均引用率为6.72，h-index为11。主要从事群论、组合论、代数计算、地图、多面体等领域研究。

甘肃省应用数学与复杂系统省级重点实验室

数学与统计学院

萃英学院

2019年10月16日