m-ary search trees when m 27: a strong asymptotics for the space requirements

  • Authors:
  • Brigitte Chauvin;Nicolas Pouyanne

  • Affiliations:
  • Département de Mathématiques, Université de Versailles-Saint-Quentin, 45, avenue des Etats-Unis, 78035 Versailles cedex, France;Département de Mathématiques, Université de Versailles-Saint-Quentin, 45, avenue des Etats-Unis, 78035 Versailles cedex, France

  • Venue:
  • Random Structures & Algorithms
  • Year:
  • 2004

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Abstract

It is known that the joint distribution of the number of nodes of each type of an m-ary search tree is asymptotically multivariate normal when m ≤ 26. When m ≥ 27, we show the following strong asymptotics of the random vector Xn = t(Xn(1)),...,(Xn(m-1)), where Xn(i) denotes the number of nodes containing i - 1 keys after having introduced n - 1 keys in the tree: There exist (nonrandom) vectors X, C, and S and random variables ρ and φ such that (Xn - nX)/nσ2 - ρ(C cos(τ2log n + φ) + S sin(τ2log n + φ)) → n→∞0 almost surely and in L2; σ2 and τ2 denote the real and imaginary parts of one of the eigenvalues of the transition matrix, having the second greatest real part.