科研之友
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摘要
We suggest a new type of problem about distances in graphs and make several conjectures. As a first step towards proving them, we show that for sufficiently large values of n and k, a graph on n vertices that has no three vertices pairwise at distance k has at most (n - k + 1)(2)/4 pairs of vertices at distance k.
- 出版日期2013-11
