Events and Values with the Same Name (DPL Code)
Although you cannot have two events with the same name or two values with the same name, you can have an event and a value with the same name. For example, this definition:
decision Research_Funding.{Low,Medium,High} = 30,52.5,80;
could be replaced with these two:
decision Research_Funding.{Low,Medium,High};
value Research_Funding given Research_Funding =
30,52.5,80;
Values defined with events and values defined separately can be used in exactly the same ways. DPL can tell whether you are referring to the value or to the event by the context.
Remember, though, if you assign numbers to the outcomes of a chance event as part of its definition and this event depends on other events, you must provide one number for each combination of conditioning event states and states of the chance event you are defining. Consider the following definition of the chance event called Research_Cost, which includes the cost of each outcome.
chance Research_Cost.{Low,Moderate,Outrageous}
given Research_Funding,Research_Time =
//Research_Funding Research_Time
{0.6,0.2}, //Low Short
{0.4,0.3}, //Low Medium
{0.2,0.4}, //Low Long
{0.4,0.3}, //Medium Short
{0.4,0.3}, //Medium Medium
{0.2,0.4}, //Medium Long
{0.2,0.4}, //High Short
{0.2,0.4}, //High Medium
{0.1,0.4} //High Long
=
80, 100, 125, //Low Short
80, 100, 125, //Low Medium
80, 100, 125, //Low Long
80, 100, 125, //Medium Short
80, 100, 125, //Medium Medium
80, 100, 125, //Medium Long
80, 100, 125, //High Short
80, 100, 125, //High Medium
80, 100, 125; //High Long
In this example, the numbers associated with the outcomes of the chance event are the same for all combinations of conditioning event states. The numbers only change with the states of the chance event you are defining. If the value depends only the states of the event whose name it shares, and not on this event's conditioning events, it may be simpler to define them separately.
chance Research_Cost.{Low,Moderate,Outrageous}
given Research_Funding,Research_Time =
//Research_Funding Research_Time
{0.6,0.2}, //Low Short
{0.4,0.3}, //Low Medium
{0.2,0.4}, //Low Long
{0.4,0.3}, //Medium Short
{0.4,0.3}, //Medium Medium
{0.2,0.4}, //Medium Long
{0.2,0.4}, //High Short
{0.2,0.4}, //High Medium
{0.1,0.4}; //High Long
value Research_Cost given Research_Cost = 80, 100, 125;
In an Influence Diagram, this dependence would be represented by green arrows from Research_Funding and Research_Time to Research_Cost.
Versions: DPL Professional, DPL Enterprise, DPL Portfolio
See Also