Abstract: The inference in general Bayesian netw orks is NP hard. However, computations can be usually reduced by means of simpli fying the structures of Bayesian networks with respect to the given query. In th is paper, three operations, omitting, replacing and traversing operations, are p roposed in order to realize this strategy. Empirical tests revealed that this st rategy can improve computational efficiency generally, sometimes remarkably.

Key words: Bayesian network, omitting operation, replacing operat ion, traversing operation