All conditions that describe the execution problem are constraints
(CON) of the construction objects. The associated construction
processes (CP) that serve as a solution of the execution
problem are the tasks tT of the construction objects (S: CP = T).
The as-is state conditions are the prerequisites (PR) of the tasks.
Conditions from the target state describe the results (RE) of the
tasks, ðCON ¼ PR [ REÞ. Hence, the execution problem describes
the requirements that the tasks have to satisfy. To change an asis
state to a requested target state, one construction task or a set
of construction tasks have to be executed. This sequence of construction
tasks, which leads to state modifications of the associated
elements, defines a solution for a given construction problem. Each
execution problem can consist of one or more constraints
ðP : CON ¼ PR [ REÞ. For example, constructing a wall can be represented
by one building component. If the wall contains a window,
the case problem consists of constraints for the wall, the contained
opening, and the associated window.