SUICIDIO DE SU HIJA

In an exemplary effort to define a suitable and comprehensive PSS structure, Hopkins (1999) suggested to build on elements of both geographic modelling and planning according to an object-oriented approach and, as such, to distinguish actors, activities, flows, investments, facilities, regulations, rights, issues, forces, opportunities and constraints. This apt suggestion acknowledges the fact that the urban environment is the result of the actions and reactions of various parties that attempt to achieve particular personal goals within the boundaries set by the institutional context and cultural and political norms. For example, in order to achieve particular desires individuals and households will try to find a house that provides them maximum utility, within constraints set by availability, awareness, affordability, and so on. In reaction to this latent demand, the housing industry will try to offer a housing stock which satisfies this demand, subject to the limitations set by the government in terms of, for example, housing norms, building permits, and land use plans. The role of planning authorities in this regard is to coordinate this process; to set particular goals, norms and guidelines approved through some democratic process; and to try to improve the quality and performance of the system by taking a more active role in stimulating particular developments or even taking part in investments themselves. Because this process is public in essence, planning authorities are, at least officially, guided by a set of high-level goals or principles, which reflect how political parties cope with religious, economic, social and cultural issues pertinent for their country, region and city.

of these various influences and the outcome of the multiplicity of individuals’ actions and reactions at the aggregate level. Some change can be best viewed as being monotonic. For example, the aging of housing stock is such a process. Other change comes about as the balance of uncoordinated actions of individuals. For example, the traffic situation during morning commute hours is the result of the individual actions of all those going to work. Yet, other change is more complex in that it is the result of action-reaction chains. For example, changes in the retailing structure can be viewed as the result of actions of household, related to actions of retailers, which in turn act or react to actions of their competitors and changes in aggregate demand. In case of planning authorities, change is actively planned, and often many decisions are coordinated, negotiated, and so on.

Evidently, PSS need to comply with the quintessence of planning, which is equally well in the underlying complex network of interdependencies and interactions between various autonomous parties involved in the process as in the physical environment. Given the fact that the actual strengths of multi-agent technology are its anthropomorphic nature and complex problem solving capabilities, it is reasonable to expect that PSS will meet this fundamental requirement when multi-agents form the rationale of the overall framework. From the previously described settings of urban plan development, the following distinction in main layers of agents is deducible:

– the urban planning team

– individuals and households

– firms and organizations

– the natural environment

– the physical environment

– the institutional context

– the political environment

The ‘urban planning team’, composed of land use specialists, fulfils a central role in the urban plan development process from the very moment that it is triggered by newly defined higher-level system goals coming from the ‘institutional context’ and ‘political environment’. The team then initiates and manages the process stage of alternative plan

generation through a democratic process in which ‘individuals and households’ as well as

‘firms and organizations’ take part. The ‘natural environment’, together with the ‘physical environment’, determines the situational opportunities and constraints that are inputs to the alternative plan generation procedure.

In the subsequent process stage of alternative plan evaluation, the performance of each alternative plan is judged by means of simulating the evolution of the urban environment as a product of the interactions between all the parties involved. In this micro-simulation setting ‘individuals and households’ as well as ‘firms and organizations’ are the main players, who interact with each other and the environment. Their choices and decisions affect the conditions of the ‘natural environment’ and ‘physical environment’, and vice versa. In this evolutionary process the ‘urban planning team’ can have a guiding role by stimulating certain developments and preventing others, which will provide the system user with insights into the necessity of guidance and the effectiveness of different types or degrees of guidance. The team’s role concerns relatively short-term guidance in comparison with the long-term monitoring role of the ‘institutional context’ and the ‘political environment’.

3.4 CONCLUSIONS AND DISCUSSION

To date, the attempts to design or implement PSS from a multi-agent perspective have been largely restricted to micro-simulation applications. The discussion above, however, indicates that multi-agent technology can be utilized for various purposes at various levels of PSS, supported by the fact that many researchers in other areas have become convinced of the contributions it can make to the capabilities of computer systems. On the one hand, agents have the clear potential to simplify our use of PSS by hiding complexities, by offering guidance and assistance, or by taking over tedious tasks. On the other hand, they can enhance the systems by means of their ability to tackle complex problems through modularity and flexibility. It is undisputable that PSS will benefit from the fact that a multi-agent representation allows one to bring together the knowledge, methods, models and software components that have been developed over the last decade. Moreover, its capabilities to provide an intelligent formal framework allows for easier management of PSS, as new knowledge, models, cases and so on can be more easily added to update the system.

Along with the promises of multi-agent technology, however, also comes potential danger (Norman, 1994). This especially concerns the risk of users loosing the sense of control, which comes in a close relation with users’ trust in delegating tasks to agents (Jennings and Wooldridge, 1998). In urban planning practice it is a well-known problem that planners are rather distrustful towards computational support (e.g., Geertman, 2001).

The multifunctional problem-solving power of multi-agent technology in conjunction with the overly anthropomorphic nature might be able to turn planners to accepting agent- based PSS, under the strict condition that their sense of control is clearly maintained. It is probably best to let users have continuous control over the system, i.e., to allow them to intervene at any time, to decline agents’ suggestions, to overrule their decisions, and so on. This consideration should be taken into account already in the stage of designing the system.

In order to see the implications of taking multi-agents as the guiding principle for PSS, the following chapter blends the supposed contributions of the technology to the field of planning support into a comprehensive conceptual framework for a multi-agent planning support system that, as the focus of this research, is aimed at supporting land use planning.

PART II