1. A method of defining a model using a computer system comprising: identifying said model, said model including a set of model objects and a set of relationships between said set of model objects, and wherein some of said set of model objects are partially undefined; generating a graph of said model, said graph defining which relationships of said set of relationships are directed and which relationships of said set of relationships are nondirected, said graph also defining a set of cycles, at least a first cycle defining a subset of model objects of said set of model objects, said first cycle having nondirected relationships between model objects of said subset; for at least said first cycle, determining a set of programs that can completely define said model objects of said subset; selecting a first program from said set of programs; and using said first program to completely define said model objects in said subset.