%nodes=( root => { parents => [],
                   probs => [0.01]}, # P(root)
         some => { parents => ['n1'],
                   probs => [0.74,0.21]}, # P(some|!root), P(some|root)
         other =>{ parents => ['root','n1'],
                   probs => [0.12,0.24,   # P(other|!root,!some), P(other|!root,some)
                             0.81,0.18]}, # P(other|root,!some), P(other|root,some)
         );