Abstract
An edge of a k-connected graph is said to be k-contractible if the contraction of the edge results in a k-connected graph. Let G be a 4-connected graph which has a vertex x with degree greater than four. We show that if the subgraph induced by N G (x)∩ V4(G) is not isomorphic to the path of length three, then there are at least two 4-contractible edges whose distance from x is one or less, where N G (x) and V4(G) stand for the neighborhood of x and the set of vertices of G whose degree is 4, respectively. We also show that G has at least |V≥ 5(G)| 4-contractible edges.
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Ando, K., Egawa, Y. Contractible Edges in a 4-Connected Graph with Vertices of Degree Greater Than Four. Graphs and Combinatorics 23 (Suppl 1), 99–115 (2007). https://doi.org/10.1007/s00373-007-0699-y
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DOI: https://doi.org/10.1007/s00373-007-0699-y