  HIV/AIDS spread depends upon complex patterns of interaction among various
sub-sets emerging at population level. This added complexity makes it difficult
to study and model AIDS and its dynamics. AIDS is therefore a natural candidate
to be modeled using agent-based modeling, a paradigm well-known for modeling
Complex Adaptive Systems (CAS). While agent-based models are also well-known to
effectively model CAS, often times models can tend to be ambiguous and the use
of purely text-based specifications (such as ODD) can make models difficult to
be replicated. Previous work has shown how formal specification may be used in
conjunction with agent-based modeling to develop models of various CAS.
However, to the best of our knowledge, no such model has been developed in
conjunction with AIDS. In this paper, we present a Formal Agent-Based
Simulation modeling framework (FABS-AIDS) for an AIDS-based CAS. FABS-AIDS
employs the use of a formal specification model in conjunction with an
agent-based model to reduce ambiguity as well as improve clarity in the model
definition. The proposed model demonstrates the effectiveness of using formal
specification in conjunction with agent-based simulation for developing models
of CAS in general and, social network-based agent-based models, in particular.
