Such a problem, in standard form, presents an objective function Z=f(x), of n variables x, to be minimized and a system of linear equations and/or inequalities, on the same variables, which represent the constraints and which define an admissible area for the solution.

The architectural organism is modelled as an assembly of parallelepiped shaped space entities or units, provided with a certain number of "holes" that permit functional corresponding connection. The pursued intent being optimal assembly.

The model, in its mathematical form, fits a standard Non-Linear M.P. (N.L.P.) problem, since the objective function Z is non-linear and the constraints are represented by inequalities. In its graphic form it reproduces an image of all the space units constituting the organism; moreover it is able to represent these units, in their logical and physical individuality, and their mutual relationship, as well as the ones with the external environment.

Within contemporary digital environments, there are increasing opportunities to explore and evaluate design proposals which integrate both architectural and landscape aspects. The production of integrated design solutions exploring buildings and their surrounding context is now possible through the design development of shared 3-D and 4-D virtual environments, in which buildings no longer float in space.

The scope of landscape design has expanded through the application of techniques such as GIS allowing interpretations that include social, economic and environmental dimensions. In architecture, for example, object-oriented CAD environments now make it feasible to integrate conventional modelling techniques with analytical evaluations such as energy calculations and lighting simulations. These were all ambitions of architects and landscape designers in the 70s when computer power restricted the successful implementation of these ideas. Instead, the commercial trend at that time moved towards isolated specialist design tools in particular areas. Prior to recent innovations in computing, the closely related disciplines of architecture and landscape have been separated through the unnecessary development, in our view, of their own symbolic representations, and the subsequent computer applications. This has led to an unnatural separation between what were once closely related disciplines.

Significant increases in the performance of computers are now making it possible to move on from symbolic representations towards more contextual and meaningful representations. For example, the application of realistic materials textures to CAD-generated building models can then be linked to energy calculations using the chosen materials. It is now possible for a tree to look like a tree, to have leaves and even to be botanicaly identifiable. The building and landscape can be rendered from a common database of digital samples taken from the real world. The complete model may be viewed in a more meaningful way either through stills or animation, or better still, through a total simulation of the lifecycle of the design proposal. The model may also be used to explore environmental/energy considerations and changes in the balance between the building and its context most immediately through the growth simulation of vegetation but also as part of a larger planning model.

The Internet has a key role to play in facilitating this emerging collaborative design process. Design professionals are now able via the net to work on a shared model and to explore and test designs through the development of VRML, JAVA, whiteboarding and video conferencing. The end product may potentially be something that can be more easily viewed by the client/user. The ideas presented in this paper form the basis for the development of a dual course in landscape and architecture. This will create new teaching opportunities for exploring the design of buildings and sites through the shared development of a common computer model.

Pairs of participants were set a design problem and asked to solve it in face-to-face settings. The same problem was then tackled by participants in settings using two different modes of computer-supported communication: email and an electronic whiteboard. Protocols were collected and analyzed in terms of the constraints of each tool relative to the task and to each other. The GOMS methodology was used as a way to represent the collaborative design process in a way that yields information on both the productivity and performance of participants in each of the three experimental conditions. It also yielded information on the component elements of the design process, the basic cognitive building-blocks of design, thereby suggesting fundamentally new tools that might be created for interaction in virtual environments.

A further goal of the study was to explore the nature of task differences in relation to alternative platforms for communication. It was hypothesized that design processes involving significant negotiation would be less aided by computer support than straight forward design problems. The latter involve cooperative knowledge application by both participants and are therefore facilitated by information-rich forms of computer support. The former, on the other hand, requires conflict resolution and is inhibited by non face-to-face interaction. The results of this study point to the fact that the success of collaboration in virtual space is not just dependent on the nature of the tools but also on the specific nature of the collaborative task.

Decisions taken in the ‘private design space’ of the design team or ‘actor’ are closely related to the type of support that can be provided by a Collaborative Design system: automatic checks performed by activating procedures and methods, reporting of 'local' conflicts, methods and knowledge for the resolution of ‘local’ conflicts, creation of new IT objects/ building components, who the objects must refer to (the ‘owner’), 'situated' aspects (Gero and Reffat, 2001) of the IT objects/building components.

Decisions taken in the ‘shared design space’ involve aspects that are typical of networked design and that are partially present in the ‘private’ design space. Cross-checking, reporting of ‘global’ conflicts to all those concerned, even those who are unaware they are concerned, methods for their resolution, the modification of data structure and interface according to the actors interacting with it and the design phase, the definition of a 'dominus' for every IT object (i.e. the decision-maker, according to the design phase and the creation of the object). All this is made possible both by the model for representing the building (Carrara and Fioravanti, 2001), and by the type of IT representation of the individual building components, using the methods and techniques of Knowledge Engineering through a structured set of Knowledge Bases, Inference Engines and Databases. The aim is to develop suitable tools for supporting integrated Process/Product design activity by means of a effective and innovative representation of building entities (technical components, constraints, methods) in order to manage and resolve conflicts generated during the design activity.

Decisions taken in the ‘private design space’ of the design team or ‘actor’ are closely related to the type of support that can be provided by a Collaborative Design system: automatic checks performed by activating procedures and methods, reporting of 'local' conflicts, methods and knowledge for the resolution of ‘local’ conflicts, creation of new IT objects/ building components, who the objects must refer to (the ‘owner’), 'situated' aspects (Gero and Reffat, 2001) of the IT objects/building components.

Decisions taken in the ‘shared design space’ involve aspects that are typical of networked design and that are partially present in the ‘private’ design space. Cross-checking, reporting of ‘global’ conflicts to all those concerned, even those who are unaware they are concerned, methods for their resolution, the modification of data structure and interface according to the actors interacting with it and the design phase, the definition of a 'dominus' for every IT object (i.e. the decision-maker, according to the design phase and the creation of the object). All this is made possible both by the model for representing the building (Carrara and Fioravanti, 2001), and by the type of IT representation of the individual building components, using the methods and techniques of Knowledge Engineering through a structured set of Knowledge Bases, Inference Engines and Databases. The aim is to develop suitable tools for supporting integrated Process/Product design activity by means of a effective and innovative representation of building entities (technical components, constraints, methods) in order to manage and resolve conflicts generated during the design activity.

The projects presented here are of three types: (1.) The first project compares people's evaluation of several slightly modified virtual models of a space. (2.) The second project compares how people evaluate a foam core model of a space to how they evaluate a virtual representation of the same space (3.) The third project compares people's evaluation of a real space to that of a virtual representation of this space. //

The wide range of results presented provides one argument in support of using VR simulations to study spaces and how they are perceived. For example, results shows that a virtual window serves to alleviate perceived crowding and that added furniture serves to make a virtual room feel slightly larger and less constraining. However, problems did emerge with using virtual reality simulations to gain information about peoples' behavioral reactions to a space. Thus, not all circumstances under which VR representations are used creates valid results. Differences appear to be in the type of evaluations measured (e.g. dimensional versus behavioral). More research is needed to clarify this issue.