A Generalization of the Graham-Pollak Tree Theorem to Steiner Distance
Graham and Pollak showed that the determinant of the distance matrix of a tree T depends only on the number of vertices of T. Graphical distance, a function of pairs of vertices, can be generalized to “Steiner distance” of sets S of vertices of arbitrary size, by defining it to be the fewest edges in any connected subgraph containing all of S. Here, we show that the same is true for trees' Steiner distance hypermatrix of all odd orders, whereas the theorem of Graham-Pollak concerns order 2. We conjecture that the statement holds for all even orders as well.
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