5.9.2 Characterizations of Planar Graphs 1930 Kuratowski(库拉托斯基) Two basic nonplanar graphs: Ks and K3.3▪ 5.9.2 Characterizations of Planar Graphs ▪ 1930 ▪ Kuratowski (库拉托斯基) ▪ Two basic nonplanar graphs: K5 and K3,3