Testing Diagnosis -- Propagating Evidence

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Testing Diagnosis -- Propagating Evidence

Post by jdtoellner »

I have a network that represents an electronic device. I've modeled all the conceivable failure causes and modes. The network is set up with observation nodes, target nodes, and auxiliary nodes. Some of the observation nodes are Mandatory.

When I run Testing diagnosis it first asks me to enter evidence for Mandatory nodes--to be expected. I'm my network I've made nodes that represent whether the unit powers on successfully mandatory. In the Testing diagnosis panel I'll first enter Mandatory evidence. In the Evidence panel I will then see the Mandatory evidence that I had just input. (All expected behavior.)

I can also enter evidence into the GeNIe display by right clicking on nodes. When I do this evidence propagates to other nodes. Some of this excludes certain failures in the network. For instance, in my network if the unit doesn't power on the network interface won't work. When I enter evidence that indicates the unit failed to power on, the network then indicates that there is no data appearing on the network interface. When I then run Test Diagnosis both the evidence I entered and the propagated evidence show up in the Evidence panel. I like this feature.

I'd suggest that you change the behavior of the Test diagnosis feature so that evidence propagates and shows up in the Evidence panel.

I've limited the number of observation nodes that are Mandatory. Since evidence doesn't automatically propagate the user has to enter manual evidence for things like the network not working just after specifying that the unit is powered off. This not only is an unnecessary step, I've found that I can enter inconsistent evidence. In the Test diagnosis panel I can specify that the network interface is working when the unit is powered off.

In the GeNIe window I can't do that. If I enter evidence that the unit is powered off it propagates evidence that the network is not working. If I attempt to enter evidence that the network is working I get an error message that indicates "<node> has propagated evidence set - can't clear/change it".

One minor drawback of entering evidence into the network first: I get a lot of Ranked Targets that show up as NOT RELEVANT in the Ranked Targets panel. They're at the end of the list, so it's not a big issue. I'd prefer that they not appear. (If I enter evidence into the Ranked Targets panel this evidence doesn't appear.
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