Discussiones Mathematicae Graph Theory (Nov 2017)

The Total Acquisition Number Of The Randomly Weighted Path

  • Godbole Anant,
  • Kelley Elizabeth,
  • Kurtz Emily,
  • Prałat Paweł,
  • Zhang Yiguang

DOI
https://doi.org/10.7151/dmgt.1972
Journal volume & issue
Vol. 37, no. 4
pp. 919 – 934

Abstract

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There exists a significant body of work on determining the acquisition number at(G) of various graphs when the vertices of those graphs are each initially assigned a unit weight. We determine properties of the acquisition number of the path, star, complete, complete bipartite, cycle, and wheel graphs for variations on this initial weighting scheme, with the majority of our work focusing on the expected acquisition number of randomly weighted graphs. In particular, we bound the expected acquisition number E(at(Pn)) of the n-path when n distinguishable “units” of integral weight, or chips, are randomly distributed across its vertices between 0.242n and 0.375n. With computer support, we improve it by showing that E(at(Pn)) lies between 0.29523n and 0.29576n. We then use subadditivity to show that the limiting ratio lim E(at(Pn))/n exists, and simulations reveal more exactly what the limiting value equals. The Hoeffding-Azuma inequality is used to prove that the acquisition number is tightly concentrated around its expected value. Additionally, in a different context, we offer a non-optimal acquisition protocol algorithm for the randomly weighted path and exactly compute the expected size of the resultant residual set.

Keywords