报 告 人： 罗荣 教授 （美国西弗吉尼亚大学）
报告题目：Flows of signed graphs
报告时间：2019年11月21日（周四）下午15:00
报告地点：静远楼1506学术报告厅
报告人简介：
罗荣，美国西弗吉尼亚大学数学系教授、博士生导师。主要研究图的染色理论和流理论，在 Journal of Cominatorial Theory Ser. B, Journal of Graph Theory, SIAM Journal on Discrete Math, European J. of Combinatorics等图论杂志发表论文60多篇.
报告摘要：
It was observed by Tutte that the problem of the face-coloring (map coloring) of a graph embedded on an orientable surface can be formulated in terms of integer flows of the graph. It was further extended by Bouchet (JCTB1983) for graphs on non-orientable surfaces. For graphs embedded on non-orientable surfaces, the dual version of vertex-coloring is the flow problem for signed graphs. An edge is negative if it passes through an odd number of crosscaps. Bouchet (JCTB 1983) conjectured that every flow admissible signed graph admits a nowhere-zero 6-flow. In this talk, I will report the progresses we make toward Bouchet’s 6-flowo conjecture.