Elements of GeNIe Diagrams: Node status icons
From DSL
Each node in GeNIe graph view can be marked by one of node status icons. These are tiny icons displayed in the lower right corner of the node icon. There are four different node status icons: Observed, Implied, Target, and Invalid. We will explain their meaning on simple examples.
Invalid Status Icon [ 
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The Invalid status icon [ ] marks those nodes that need updating, i.e., their values (or the probability distributions) are invalid and cannot be inquired. Invalid mark can appear together with the Target mark, but never with the Observed and Implied marks (note that when a node is observed, its value is known). To make the value valid, which will make the Invalid icon disappear, simply update the model. The following variable is invalid, i.e., its probability distribution needs recomputing:
Observed Status Icon [ 
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The Observed status icon [ ] is the simplest. It is displayed when the user notified GeNIe that the value of a node has been observed externally, i.e., the node is an evidence node. A node with the Observed icon displayed looks as follows:
Implied Status Icon [ 
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Sometimes, observing a node implies the values of other nodes. For example, observing that a patient is male in a medical decision support system will imply that he is not pregnant. GeNIe marks the nodes whose values are implied by observations of other nodes by the Implied icon [ ]. The Implied icon is identical to the Observed icon, but it is yellow in color. In the following example, the Gender of the patient has been observed to be Male and the value of the Pregnancy variable has been determined by GeNIe to be NotPregnant, .i.e. In the Definition tab of Pregnancy node, probability of NotPregnant state for Gender = Male is 1.
Target Status Icon [ 
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The Target icon [ ] has to do with GeNIe's support for relevance reasoning. Very often in a decision support system, only a small number of variables are of interest to the user. When the model used by the system is large, the amount of computation to update all variables may be prohibitive while being in a large part useless. GeNIe allows to designate those variables that are of interest to the user as targets. Target nodes are always guaranteed to be updated by the program during its updating procedure. Other nodes, i.e., nodes that are not designated as targets, may be updated or not, depending on the internals of the algorithm used, but are not guaranteed to be updated. When no nodes are designated as targets, GeNIe assumes that all variables in the model are of interest to the user, i.e., all of them are targets. The following variable (Success) is a target variable.
Controlled Status Icon [ 
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The Controlled status icon is displayed on a node if the nodes value has been controlled. You can control a node's value by selecting the Control Value option from the Node Popup Menu. See Tutorial 10: Using Control Values to learn how to control values in your models.
