Physically-based modeling has been used in the past to support a variety of interactive modeling tasks including free-form surface design, mechanism design, constrained drawing, and interactive camera control. In these systems, the user interacts with the model by exerting virtual forces, to which the system responds subject to the active constraints. In the past, this kind of interaction has been applicable only to models that are governed by continuous parameters. In this paper we present an extension to mixed continuous /discrete models, emphasizing constrained layout problems that arise in architecture and other domains. When the object being dragged is blocked from further motion by geometric constraints, a local discrete search is triggered, during which transformations such as swapping of adjacent objects may be performed. The result of the search is a "nearby" state in which the target object has been moved in the indicated direction and in which all constraints are satisfied. ...

A typical computer representation of a design includes geometric and physical information organized in a suitable combinatorial data structure. Queries and transformations of these design representations are used to formulate most algorithms in computational design, including analysis, optimization, evolution, generation, and synthesis. Formal properties, and in particular existence and validity of the computed solutions, must be assured and preserved by all such algorithms. Using tools

. In terms of conceptual structures theory, the objective of our project is the development of a pattern directed inference system[7]. It is to operate over conceptual graph terms extended to express constraints on the referent values, and the matching mechanism is to combine order sorted unification with the action of a constraint solver. This combination leverages type representation technology from the conceptual graph community[3] and constraint technology[10]. In terms of the objectives of the SEED project[6], this system will animate the elaboration and specialization of problem representations. Furthermore, a formal description of the representation and the mechanisms of its generative capabilities will clarify the theoretical basis for case retrieval and design reuse. 1 Overview of SEED SEED is an acronym for Software Environment to support the Early phases in building Design.[6] The intent of the SEED project is to create software which will support preliminary design of buil...