A computer-implemented method for modeling a target system includes
defining a conditional constraint satisfaction problem (CondCSP) that
characterizes the target system in terms of problem variables and
constraints applicable to the problem variables. The constraints include
conditional constraints, such that the variables associated with the
conditional constraints each have a respective activity status. Existence
variables are defined to represent the respective activity status of the
variables associated with each of the one or more conditional
constraints. A solution to the CondCSP is found by determining an
assignment of the problem variables and the existence variables that
satisfies the constraints.