Design agent decisions are based on information expressed as preconditions.
If the design decision has to be taken before all the information needed to evaluate
the preconditions is available, the design agent will use expectations to complete
Examples of situations that require or could benefit from the use of expectations
as substitutes for precondition information are:
1. The agent is required to provide a decision within a given time.
2. The decision-making information built into the agents is cyclic, and therefore
one of the agents has to make a decision before all the needed preconditions
are satisfied by information in the design environment.
3. Since the order of decisions influences the design and the design process, taking
a decision earlier can benefit other agents that rely on the information
resulting from the decision.
The range of situations is not limited to the ones presented above. Each of these
situations in turn requires some comment.
• The first situation occurs if there is a partial ordering of the actions of design
agents which is reflected in a design plan. In such cases, agents may be
required to complete a task before another agent can proceed, and if possible,
will have to substitute for missing information.
• The second situation can be avoided only if a formal verification process can
secure that there are no circular dependencies between the knowledge of the
MADS agents. Such techniques are difficult to implement over an agent set.
Circular dependencies typically occur because of design constraints that span
several agents, and removing them amounts to a constraint problem-solving
task across agents. If none of the agents uses an evaluation, it is possible that
the design agents will make decisions which result in conflicts. Alternatively,
MADS developers can compile out the circular dependencies by introducing
estimates. However, this approach is subject to the types of limitations discussed
in the first part of the paper.
• The use of expectations in this third case can significantly enhance the range
of options that are available in terms of the configuring the overall design process.
However, the expectation has to be a reliable substitute for the actual
information lest its use actually represents an impediment to the design process.