主讲概况：Prof. Thomas B?hme，1999年在德国伊尔梅瑙工业大学获博士学位，现为伊尔梅瑙工业大学数学与自然科学学院院长，研究领域为离散数学（主要是图论）和博弈论。
主讲内容：A well-known theorem of Lipton and Tarjan from the 1970s states that every planar graph on n vertices can be split into subgraphs each of which contains at most 2n/3 vertices by removing a set of at most 2√2√n vertices. Over the years this theorem has been extended to various classes of graphs, most notably to graphs not containing a specific graph as a minor, string graphs, and graphs that can be embedded into the d-dimensional euclidean space with bounded distortion. In the talk I will give a short overview of the field and present some so far unpublished improvements and refined proof techniques.