## Expression Builder

The Expression Builder is activated from the Build Expression item of the Table menu.

The Expression Builder assists the user in building expressions by providing a simple user interface for selecting a function and specifying arguments. When the user selects Build Expression, a dialog window appears showing all functions available for the currently edited expression (depending on the type of the currently selected node). This dialog is shown in figure 1. The functions are organized in a number of categories to make it faster to find a particular function.

Figure 1: The Select Function dialog of the Expression Builder.

After the user has selected a function the Specify Arguments dialog of the Expression Builder appears. This dialog prompts the user for arguments to the selected function. Figure 2 shows the Specify Arguments dialog.

Each argument must itself be an expression and can therefore be built using the Expression Builder. Pressing the Build button next to the argument edit box will start the Expression Builder for that argument.

If you want to use a parent in an expression, you must use its unique name. You can select a parent in the Parents list and then press the Insert button to insert it into the argument you are currently editing. Only discrete chance nodes and decision nodes can appear in expressions.

Figure 2: The Specify Arguments dialog of the Expression Builder.

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