## Prop Max Fast Retract

The prop max fast retract propagation is activated either by selecting the Prop Max Fast Retract item of the network menu or by pressing the corresponding button in the run mode tool bar (see figure 1). If you are using auto propagation, you can specify Hugin to use this propagation method.

The prop max fast retract propagation method can be used in Bbns containing only discrete chance nodes. It is similar to the max normal method except that it shows the nodes which have recieved evidence differently. Instead of showing the values of the states of the node which has recieved evidence, the values of the states are shown as if this node had not recieved evidence. That is, the values of the node being in each of its states given the evidence entered in all other nodes. To indicate that the node has in fact recieved evidence, the belief bars use the color code for evidence (default: Red).

This propagation method can be used to check if the evidence corresponds to (one of) the most likely configuration(s) or if the evidence suggests that one of the less likely configurations has been observed (if a state of a node has been observed which does not have the value: 100).

Figure 1: The prop max fast retract button from the run mode tool bar.

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