Feature-based design evaluation through constraint structure unification

Constraint structures are presented as a new knowledge structure to encode both engineering part designs and constraints on those designs. Using a common representational form for both designs and constraints results in a number of practical advantages for a design evaluation system grounded on constraint structures. First, a graph unification algorithm generalized to operate on constraint structures is used as a mathematically elegant means of applying constraints to designs. As a side-effect of constraint structure unification, constraints are attached to design representations. Once the constraints become a part of the design representation, a part is able automatically to reevaluate relevant constraints following interactive changes to design parameters without re-invoking the unification algorithm