Journal of the Operations Research Society of China ›› 2020, Vol. 8 ›› Issue (1): 105-116.doi: 10.1007/s40305-018-0214-6

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Connectivity of Minimum Non-5-injectively Colorable Planar Cubic Graphs

Jing Jin1,2, Bao-Gang Xu1   

  1. 1 Institute of Mathematics, School of Mathematical Sciences, Nanjing Normal University, Nanjing 210023, China;
    2 College of Taizhou, Nanjing Normal University, Taizhou 225300, Jiangsu, China
  • Received:2017-10-12 Revised:2018-04-09 Online:2020-03-30 Published:2020-02-18
  • Contact: Jing Jin, Bao-Gang Xu E-mail:jinjing19841@126.com;baogxu@njnu.edu.cn

Abstract: Suppose that G is a planar cubic graph with χi(G)> 5. We show that if χi(H) <χi(G) for each planar cubic graph H of order less than G, then G is either a 3-connected simple planar cubic graph, or a planar graph obtained from a simple cubic 3-connected planar graph by adding some earrings. This shows that a minimum non-5-injectively colorable simple planar cubic graph must be 3-connected.

Key words: Planar cubic graphs, Connectivity, 3-connected, Injective coloring

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