We develop an architecture for a product master model that federates CAD systems with downstream application processes for di erent feature views that are part of the design process. The architecture addresses especially the need to make persistent associations of design information with net shape elements. Moreover, the design respects the need of commercial CAD systems (and of downstream applications) to maintain proprietary information that must not be disclosed in the master model. Two case studies consider the requirements on the master model architecture, for geometric dimensioning and tolerancing, and for manufacturing process planning using NC machining. We discuss how to reconcile the associated feature views and how to update them under net shape redesign. The case studies indicate that many design changes that arise from these downstream views can be formalized by a well-de ned problem on dimensional and geometric constraints.

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We present three mechanisms for maintaining consistent product views in a distributed product information data base. The mechanisms are used when one of the views makes a change to the product model and the other views must be updated to maintain consistency.

Geometric problems defined by constraints can be represented by geometric constraint graphs whose nodes are geometric elements and whose arcs represent geometric constraints. Reduction and decomposition are techniques commonly used to analyze geometric constraint graphs in geometric constraint solving.In this paper we first introduce the concept of deficit of a constraint graph. Then we give a new formalization of the decomposition algorithm due to Owen. This new formalization is based on preserving the deficit rather than on computing triconnected components of the graph and is simpler. Finally we apply tree decompositions to prove that the class of problems solved by the formalizations studied here and other formalizations reported in the literature is the same.

We present an approach for handling geometric constraint problems with under-constrained configurations. The approach works by completing the given set of constraints with constraints that can be defined either automatically or drawn from an independently given set of constraints placed on the geometries of the problem. In both cases, the resulting completed set of constraints is not over-constrained. If every well-constrained subproblem in the given underconstrained configuration is solvable, the completed constraint problem is also solvable.