报告人：范更华 （福州大学，教授）
报告时间：2023年3月26日(星期天)上午9：00
报告地点：章辉楼441
联系人：晏卫根
欢迎广大师生参加！
报告摘要：Let G be a graph with an orientation on each edge and let A be an abelian group. A function f, from the edge set E(G) of G to the nonzero elements of A, is call an A-flow of G if at each vertex v ∈ V (G), the sum of f(e) over every e with head v is equal to the sum of f(e) over every e with tail v. Tutte conjectured that if a graph has a Z-flow, then it has a Z-flow f such tat |f(e)| ≤ 4 for each e ∈ E(G), which is related to graphs embedded in orientable surfaces. Bouchet conjectured that if a signed graph has a Z-flow, then it has a Z-flow f such tat |f(e)| ≤ 5 for each e ∈ E(G), which is related to graphs embedded in nonorientable surfaces. The theory of flows has a strong connection with the coloring of graphs, especially with the Four Color Problem of plane graphs (graphs embedded in sphere). In this talk, we give a brief survey of recent results on flows and their applications to subgraph union problems.
报告人简介：范更华，福州大学教授、博士生导师。国家杰出青年科学基金获得者、中央直接掌握联系的高级专家、享受国务院政府特殊津贴专家、福建省杰出科技人才。曾任福州大学副校长，中国数学会组合数学与图论专业委员会主任，全国组合数学与图论学会理事长。现任福州大学离散数学及其应用教育部重点实验室主任，中国运筹学会副理事长，国际图论界权威刊物《图论杂(Journal of Graph Theory)执行编委(Managing Editor)。
范老师主要从事图论领域中的结构图论、极图理论、带权图、欧拉图、整数流理论、子图覆盖等方向的基础理论研究。同时也致力于图论在大规模集成电路设计中的应用。他一个关于图的Hamilton性方面的成果以"范定理"、"范条件"被国内外同行广泛引用。一些成果还作为定理出现在国外出版的教科书中。范老师获1998年度国家杰出青年科学基金;一直主持国家自然科学基金委重点项目。曾获2003年度教育部科技一等奖、 2005年度国家自然科学二等奖。
