应数学与统计学院张和平教授和徐守军教授邀请，南开大学数数学科学学院李佳傲老师将于2020年9月2日进行线上学术报告。

报 告：Nowhere-zero flows of signed graphs

时 间：9月2日下午3:40

地 点：腾讯会议, ID:445 319 208, 密码:0902

摘 要：Parallel to Tutte's flow theory on ordinary graphs, Bouchet (1983) introduced a general flow theory for signed graphs, arising from the dual of local tension of graphs embedding on non-orientable surfaces. In contrast to Tutte's flow conjectures, Bouchet (1983) conjectured that every flow-admissible signed graph admits a nowhere-zero 6-flow. Bouchet himself proved that such signed graphs admit nowhere-zero 216-flows，and Zyka(1987) further improved to 30-flows. In this talk, we will present our recent work joint with DeVos, Lu, Luo, Zhang, Zhang (JCTB, 2020, online), showing that every flow-admissible signed graph admits a nowhere-zero 11-flow. We shall also discuss some related results and problems.

欢迎广大师生参加！

报告人简介

李佳傲，中国科学技术大学本科硕士，美国西弗吉尼亚大学博士。现任南开大学数学学院讲师。主要研究兴趣是图论中的整数流问题，图染色，网络与组合优化问题等。已完成和发表论文近二十篇，现主持国家自然科学基金青年项目和天津市自然基金青年项目各1项。

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