ITR/SY: Constrained Objects for Modeling Complex Systems

The modeling of complex systems using the concept of constrained objects is investigated. A constrained object is one whose internal state is regulated by a set of invariants, or constraints. When several constrained objects are aggregated to form a complex object, their internal states might further have to satisfy interface constraints. The resultant behavior of the complex object is determined using logical inference and constraint satisfaction. Thus, constrained objects are a declarative counterpart of traditional objects (found in object-oriented languages). The proposed modeling paradigm has diverse uses, including engineering and organizational modeling, and supports constraints as well as preferences. The computational model for constrained objects provides constraint satisfaction, optimization, and relaxation techniques. A visual representation for constrained objects is also provided in such a way that the components of the visual form have logical counterparts in the underlying model. Research areas of interest include language design, execution, and applicatons. In particular, issues arising in model revision (i.e., incremental constraint satisfaction) and model inconsistency (i.e., fault diagnosis) will be investigated. The results from this research will be incorporated in the modeling environment, which is expected to make a significant advance over current modeling tools for engineering design.