Exact structure discovery in Bayesian networks with less space

  • Authors:
  • Pekka Parviainen;Mikko Koivisto

  • Affiliations:
  • University of Helsinki, Finland;University of Helsinki, Finland

  • Venue:
  • UAI '09 Proceedings of the Twenty-Fifth Conference on Uncertainty in Artificial Intelligence
  • Year:
  • 2009

Quantified Score

Hi-index 0.00

Visualization

Abstract

The fastest known exact algorithms for score-based structure discovery in Bayesian networks on n nodes run in time and space 2nnO(1). The usage of these algorithms is limited to networks on at most around 25 nodes mainly due to the space requirement. Here, we study space--time tradeoffs for finding an optimal network structure. When little space is available, we apply the Gurevich--Shelah recurrence---originally proposed for the Hamiltonian path problem---and obtain time 22n-snO(1) in space 2snO(1) for any s = n/2, n/4, n/8, ...; we assume the indegree of each node is bounded by a constant. For the more practical setting with moderate amounts of space, we present a novel scheme. It yields running time 2n(3/2)pnO(1) in space 2n(3/4)pnO(1) for any p = 0, 1, ..., n/2; these bounds hold as long as the indegrees are at most 0.238n. Furthermore, the latter scheme allows easy and efficient parallelization beyond previous algorithms. We also explore empirically the potential of the presented techniques.