# Probability, True Cost, False Cost Inputs

A binary event can only take one probability value input. The probability can be specified directly in the binary event's node data or it can be provided by a single value node, another binary event or a gate.

A binary event may also have a true state cost. The true state cost can be specified directly in the binary event's node data or it can be provided by a single value node. Binary events may also have false state costs. False state costs behave similarly.

To summarize, a maximum of three value nodes may be connected to a binary event: one for probability, one for true state cost and one for false state cost. Value nodes connected as true or false costs will have a T or F near their connection to indicate this.

If any of the values associated with a binary event (probability, true cost, false cost) need to be an expression involving more than one value, these expressions must be contained in separate value nodes (e.g., one for probability, one for true cost, one for false cost). These value nodes can then be linked to the binary event. Any value referenced in the expression of a value node must must be connected to the value. A value node can have an unlimited number of connections to it.

* Versions:* DPL Fault Tree

*See Also*