e3value user manual, first release

5.11 Computing property values

All examples so far have used constant property values. However, in e3value , property values can be computed from other property values using an expression language that consists of two parts: a navigation language to refer to values defined in the model and a set of arithmetical operators to compute values. Appendix C defines the expression language of e3value . The e3value editor provides a simple technique by which you can instruct the editor to construct navigation expressions for you.

Figure 5.12:The pricing is dependent on the total number of Train trips sold.

Bulk price reduction. Consider the example in figure 5.12. In this model, the interface of the Railway company is called trip-supply. The valuation associated to the in-port of this interface is that the price of the trip is f200 if the number of occurrences in the market scenario is less than 1 000 000, otherwise it is f190.

In the example, the navigation expression evaluates to f10,000,000 = 10 × 1,000,000 and so the train tickets in this market scenario cost f190

Variable price. In figure 5.13 the valuation expression of port vp12 computes the price of a Train trip as FixedTariff + 0.5 Distance. FixedTarrif is a user-defined property of the port vp12 and Distance is a user-defined property of the value transfer ve17.

Figure 5.13:A Traveler obtains a Train trip from a Railway company.