Shallow-Low-Light Trees, and Tight Lower Bounds for Euclidean Spanners

13 years 10 months ago

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We show that for every n-point metric space M and positive integer k, there exists a spanning tree T with unweighted diameter O(k) and weight w(T) = O(k · n1/k ) · w(MST(M)), and a spanning tree T with weight w(T ) = O(k) · w(MST(M)) and unweighted diameter O(k · n1/k ). Moreover, there is a designated point rt such that for every other point v, both distT (rt, v) and distT (rt, v) are at most (1 + ) · distM (rt, v), for an arbitrarily small constant > 0. We prove that the above tradeoffs are tight up to constant factors in the entire range of parameters. Furthermore, our lower bounds apply to a basic one-dimensional Euclidean space. Finally, our lower bounds for the particular case of unweighted diameter O(log n) settle a long-standing open problem in Computational Geometry.

Yefim Dinitz, Michael Elkin, Shay Solomon

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