# Requisite Ancestors

Inspecting requisite ancestors for a decision node may be useful for solving a network with decisions and utlity functions as a traditional influence diagram where all observations and all decisions of the past must be remembered.

Not all available observations matter when a decision must be made. In order to get the optimal solution of an influence diagram, relevant past observations and decisions must be added as parents of each decision node in the LIMID network.

Ancestors of a decision node is said to be requisite if the value of the ancestor may affect the optimal choice of the decision.

## Inspect the requisite ancestors of a decision node

Select a decision node. Click Network -> Analysis -> Show requisite ancestors for decision.

Requisite ancestors will be marked with a green V (see Figure 1).

Figure 1: Requisite ancestors are marked with a green V.

Note

If the model is a class, this function is only available in run-mode. If the model is a flat net, the function is available in both edit-mode and run-mode.