On minimum and maximum spanning trees of linearly moving points

N. Katoh, T. Tokuyama, K. Iwano

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19 Citations (Scopus)


In this paper we investigate the upper bounds on the numbers of transitions of minimum and maximum spanning trees (MinST and MaxST for short) for linearly moving points. Here, a transition means a change on the combinatorial structure of the spanning trees. Suppose that we are given a set of n points in d-dimensional space, S={p 1, p 2, ... p n }, and that all points move along different straight lines at different but fixed speeds, i.e., the position of p i is a linear function of a real parameter t. We investigate the numbers of transitions of MinST and MaxST when t increases from-∞ to +∞. We assume that the dimension d is a fixed constant. Since there are O(n 2) distances among n points, there are naively O(n 4) transitions of MinST and MaxST. We improve these trivial upper bounds for L 1 and L distance metrics. Let k p (n) (resp.[Figure not available: see fulltext.]) be the number of maximum possible transitions of MinST (resp. MaxST) in L p metric for n linearly moving points. We give the following results in this paper: κ1(n)=O(n 5/2 α(n)), κ(n)=O(n 5/2 α(n)),[Figure not available: see fulltext.], and[Figure not available: see fulltext.] where α(n) is the inverse Ackermann's function. We also investigate two restricted cases, i.e., the c-oriented case in which there are only c distinct velocity vectors for moving n points, and the case in which only k points move.

Original languageEnglish
Pages (from-to)161-176
Number of pages16
JournalDiscrete & Computational Geometry
Issue number1
Publication statusPublished - 1995 Dec

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Geometry and Topology
  • Discrete Mathematics and Combinatorics
  • Computational Theory and Mathematics


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