Algorithm

• In general: NP Complete

• Easy for polytrees

  • I.e. only one undirected path between nodes

• Express P(X|E) by

  • 1. Recursively passing support from ancestor down
    • “Causal support”
  • 2. Recursively calc contribution from descendants up
    • “Evidential support”

• Speed: linear in the number of nodes (in polytree)

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