Modeling positive and negative gene interactions in network reliability model

In Costanzo10's paper, there are positive and negative genetic interactions that indicate antagonizing and cooperative functions of the two genes involved, respectively. The extreme case negative gene interaction is synthetic lethality.  Synthetic lethality can be modeled by parallel configuration. Positive/Antagonizing interactions may be modeled by state vectors of the nodes involved. In fact, state vector is a general way for network modeling.