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Second, quite similar to the first issue, explicitly modeling con-
straints under which an effector action is successful or fails is
uncommon at first. As usual, model developers tend to neglect the
value of introducing explicit constraints on the grounds that they
are unnecessary if a model is built correctly. But this reasoning is
deceptive as most errors and flaws are introduced unintentionally.
Explicitly modeling constraints has proven to be very useful.
Multiple interactions between agents of different types presented a
new challenge, when developing the second case study which considers
a specific military scenario (see appendix A.2 for more details). In
this case, the most dicult part of model development was to ensure
correct coordination between agents. Modeling various information
exchange relations and subsequent actions to be carried out by the
agents was a challenging task. Even though only three different types
of agents are considered, it was sometimes dicult to keep track of
the intricate interplay of mutiple agents.
Like in the first case study, the GRAMS reference model served very
well as a guideline throughout the development process. The strict
seperation of events and actions defined by the GRAMS reference
model turned out to be helpful also. This separation allowed the
construction of complex agent behaviors where each event could
trigger different actions at the same time.
While being beneficial, this caused trouble at the same time. In fact,
it turned out that effects of an event are intricate to analyze and debug.
This is not necessarily a drawback of the GRAMS reference model,
but has at least two reasons: First, the example implementation and
the tool chain available did not support all aspects of the GRAMS
reference model very well and provided only few debugging features.
Second, and perhaps more notably, modeling sophisticated interaction
patterns may exhibit a certain immanent complexity.
The third application deals with representing coordination efforts
between multiple rescue units due to a massive trac accident. After
an accident is reported a coordinating oce has to order available units
(like police, emergency doctor, fire fighters and towing service) to the
