In a DPL Influence Diagram, an influence arc between nodes indicates conditioning, dependence or timing. Influence arcs are created automatically by DPL when conditioning is added in node data. However, you can also create, modify, delete, and move arcs directly.
Creating an Influence Arc
To create an influence arc between two nodes, click Influence Diagram | Arc | Add. The cursor will become an arrow out node. Click on the node that the influence arc will lead out of. Then the cursor will become an arrow in node; click on the node that the influence arc will lead into. Alternatively, you can hold down the Shift key and click first on the node where the arc will originate and then click on the node the arc will lead to.
Modifying the type of influence arc
Once you have placed an influence arc, you can change its type double-clicking on the arc. Similar to nodes -- a selected influence arc turns magenta. The Influence Type dialog appears. Select which type of conditioning you would like. When you create an arc, by default it is drawn with black arrowheads, indicating timing only. In the Influence Type dialog you can also choose to define a certain type of conditioning as the default setting for influence arcs into nodes of the type that the arc you are editing leads into. E.g., if you are modifying the type of an influence arc into a chance node, you can tell DPL that whenever you create an arc into a chance node you want the default conditioning to be as specified in the dialog.
Straightening or bending an influence arc
To make an influence arc bend, click-and-drag it. A bend arc positioning cursor will will appear. Use the mouse to stretch the arc into the desired shape, then release the click to re-draw arc.
If you wish to straighten an arc(s) that is currently curved, select the arc(s) and choose Influence Diagram | Arc | Straighten.
Creating Arcs Automatically
DPL can construct arcs in an Influence Diagram based on the data and formulas you have entered in node data. Click Model | Influence/Arc | From Formulas to generate these arcs all at once.
Versions: DPL Professional, DPL Enterprise, DPL Portfolio