e3value user manual, first release

4.3 Dependency paths

A dependency path is an acyclic graph starting with one or more customer needs and ending in one or more boundary elements. The meaning of a dependency path is that if one of its roots is triggered in a contract period, all value interfaces through which the path passes are triggered in the contract period. This is all we need to know to compute the value flows generated by a customer need.

Mathematically, a dependency graph is a rooted acyclic graph. It may have more than one root, and all its roots are customer needs. It may have more than one boundary element as terminal. There must be no cycles in a dependency graph, because otherwise there could be infinitely many transactions triggered by one occurrence of a customer need.

Dependency paths abstract from all operational activities that an actor performs to request and provide value objects. In particular, a dependency graph abstracts from all time ordering of transactions and merely connects all value transactions that occur to satisfy a customer need.