科研之友
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摘要
A graph is H-free if it contains no H as a subgraph. The diamond graph is the graph obtained from K-4 by deleting one edge. We prove that if G is a connected graph with order n >= 10, then there exists a subset S subset of V(G) with vertical bar S vertical bar <= n/5 such that the subgraph induced by V(G) \ N[S] is diamond-free, where N[S] is the closed neighborhood of S. Furthermore, the bound is sharp.
