A method and computer program product models connections for a system having a plurality of components, having component terminals, and connections. The connections are located to selectively connect the components of the system to each other. The method and computer product models signal levels for nodes of the system as a variable wherein the nodes of the system are representative of the connections. Each potential component terminal connection of the connections that could potentially influence the signal level on each of the nodes is modeled, as a qualitative variable. This results in each node of the system being modeled with n+1 variables.