报告题目：Modulo flows and Integer flows of signed graphs
时 间：2025年9月8日（星期一）10：00
地 点：科研楼18号楼1102
主 办：数学与统计学院
参加对象：相关方向教师和研究生
报告摘要：Nowhere-zero flows of unsigned graphs were introduced by Tutte in 1954 as a dual problem to vertex-coloring of (unsigned) planar graphs. The definition of nowhere-zero flows on signed graphs naturally comes from the study of embeddings of graphs in non-orientable surfaces, where nowhere-zero flows emerge as the dual notion to local tensions. Nowhere-zero flows in signed graphs were introduced by Edmonds and Johnson in 1970 for expressing algorithms on matchings, but systematically studied first by Bouchet in 1983. Bouchet also stated a conjecture which occupies a central place in the area of signed graphs: Every flow-admissible signed graph admits a nowhere-zero 6-flow. There is a significant difference in the flows of signed graphs and unsigned graphs. In this talk, I will talk about the progress on the development of the flow theory of signed graphs.
报告人简介：罗荣，西弗吉尼亚大学数学系Eberly 杰出教授，本科和硕士毕业于中国科技大学，2002年在美国获得博士学位，师从国际著名图论学家张存铨教授。主要从事图的染色、流理论和圈覆盖以及相关应用的研究。在图的边染色领域，对Vizing几个猜想取得一系列重要进展；在流理论和圈覆盖领域，尤其是符号图流和符号圈覆盖方面取得系列突破。先后在J. Combin. Theory B、J. Graph Theory、SIAM Discrete Math.等杂志发表论文近90篇。