Propagation of multiple observations in QPNs revisited

Abstract. The sign-propagation algorithm for inference with a qualitative probabilistic network has been designed to handle a single observation at a time. Multiple observations can in essence be dealt with by entering them consecutively and combining the results of the successive propagations, or by entering them for a newly added dummy node. We demonstrate that both approaches can yield weaker results than necessary. We identify the causes underlying this unnec-essary weakness and adapt the propagation algorithm so as to provide for the strongest possible results upon inference.