In DynRisk a model is represented by a graphical structure called an 窶彿nfluence diagram窶. An influence diagram consists of two types of objects: 窶從odes窶 and 窶彳dges窶. The nodes represent the variables in the model, while the edges represent dependencies between these variables. In order to build a DynRisk model, it is necessary to understand the 窶彭ata flow窶 through the model during the simulations.
The data flow is essentially determined by the edges in the model. If there is an edge going from, say node 1 to node 2, then there will be a data flow from node 1 to node 2 during the simulations. This also implies that node 1 has to be calculated before node 2 in each simulation. More generally there is a data flow from one node to another if there is a 窶彭irected path窶 of edges going from the first node to the second.
As the values flow through the model, they may be transformed and combined many times. Transformations may occur as values flow through the edges by the use of 窶彳dge functions窶. Furthermore, values flowing into a node are combined using one or two 窶徙perators窶.
As an example we consider a model consisting of three nodes, called 窶廣ctivity 1窶, 窶廣ctivity 2窶, and 窶廣ctivity 3窶. The nodes represent activities in a certain project, and the output values are the points of time when the activities finish. Activities 1 and 2 start at time zero, while Activity 3 starts as soon as both of the first two activities are finished.
