THE NUMBER OF REMOVABLE EDGES IN PLANAR 3-CONNECTED GRAPHS
3连通平面图的可去边数

An edge e of a 3-connected graph G is said to be removable if G - e is a subdivision of some 3-connected graph. Let v denote the order of G. It is proved in this paper that there are at least (v+4)/2 removable edges in planar 3-connected graphs with v > 6 . The lower bound is reachable.