## Propagation

One of the propagation functions can be activated either by selecting one of the Prop items in the Network menu or by pressing one of the four propagation buttons in the run mode tool bar. Figure 1 shows these propagation buttons. You can also specify Hugin to use auto propagation which will make it propagate every time you enter new evidence.

Figure 1: The four propagation buttons from the run mode tool bar. Propagation methods for these buttons are (from left to right): sum normal, max normal, sum fast retract, and max fast retract.

The propagation function is used to make Hugin update all probabilities, distribution functions, and expected utilities of the discrete chance nodes, the continuous chance nodes, and the decision nodes, respectively.

There are four different propagation methods: Sum normal, max normal, sum fast retraction, and max fast retraction. The most commonly used method is the sum normal which updates all probabilities according to the entered evidence. The other methods have special purposes which you can read about in their description sections.

Back