ABSTRACT
In Table 9.1, four quadrants or parts may be distinguished. The condition set (upper left part of the table) consists of all the relevant condition subjects or attributes that have an influence on the decision-making process. In this example, both conditions, C1 and C2, in the specified table relate to distances (i.e. C1 represents the distance (X) to a harbour, and C2 represents the distance (X) to a railway station). The action set (lower left part of the table) contains all possible actions a decision-maker is able to
follow. In Table 9.1, the action set refers to how a potential location site is evaluated in terms of supply possibilities of raw materials. Therefore, action A1 evaluates these possibilities. The condition space (upper right part of the table) specifies all possible combinations of condition states (CS). These condition states represent the relevant sets or categories of possible value outcomes for a particular, given condition. In this example, two condition states, CS11 (X<1000) and CS12 (Xā 1000), are specified for condition C1; and three condition states, CS21 (X<250), CS22 (250ā Xā 450) and CS23 (X>450), for condition C2. Note that with respect to the categorization of the conditions, two important logical requirements or constraints must be fulfilled, i.e. exhaustivity and exclusivity. Exhaustivity means that the DT must account for all possible states that a condition is able to take. The exclusivity requirement refers to the fact that each combination of
Decision Support Systems in Urban Planning. Edited by Harry Timmermans. Published in 1997 by E & F N Spon. ISBN 0 419 21050 4
condition states has to be included in one and only one column of the DT, or in other words, condition state alternatives have to be mutually exclusive. The action space (lower right part of the table) contains the categorization of all the possible action states. In Table 9.1, three different action states (i.e. ‘good’, ‘medium’, ‘bad’) are used to evaluate a location site with respect to the supply of raw materials. Finally, any vertical linking of an element out of the condition states with an element of the action states produces a socalled logical rule. This logical rule is in fact a simple decision rule.
