Evaluation of Environment Contextual Services in Multiagent Systems - Agents and Artificial Intelligence - page 191

what information is available to compute the agent context depend on the agent-based
simulation (ABS) framework.
In most ABS frameworks, at each simulation step, a scheduler activates sequentially
all the agents and each activated agent computes its local context to choose one action to
execute. The classical ABS frameworks are designed to support this activation process.
For example, in the platforms C ORMAS [2] and M ASON [10], the scheduler activates
a standard method for each agent. This method is specialized by the designer to adapt
the agent behavior. In the Logo-based multi-agent platforms such as TurtleKit [7] or
the S TA R L OGO system 1 , an agent has an automaton that determines the next action to
perform.
The choice of these platforms to be agent-oriented, with a light environment support,
implies that the computation of the context is repetitive because it is computed in each
agent at each time cycle during the simulation execution. This computation is done in
each agent even if the agent context does not change between two time cycles and/or if
several agents share the same context during a time cycle. Here, the evaluation consists
in the cost comparison of the context filtering either in each agent after the activation or
in the environment during the scheduling process.
Example. In this paper, we consider a crisis management application where several
emergency services must be coordinated in order to reduce the crisis effects. A crisis
situation is a dynamic phenomenon defined by the initial situation, which depends on
place and time, and by the impact on population and infrastructure. We focus our exam-
ple on a specific point which is the victim evacuation. This task consists in coordinating
two agents playing the role medical porter . The goal of the medical porters is to shift a
victim to an emergency vehicle. This action requires one medical porter with the skill
medical monitoring and one medical porter with the skill victim handling .Thefirst
skill allows the medical porter to monitor the victim and to inform the hospital of the
evolution of the victim health. The second skill is necessary to handle the victim.
Each simulation component (agents, messages and objects) is situated on a grid. In
this example, we consider that the victims belong to the set of the objects because they
are not autonomous. The agents (medical porter) act in this environment and cooperate
in order to evacuate victims. A medical porter can move randomly or towards a given
direction , and it possesses only one skill. It can either monitor or handle a victim, but
the two skills are required to evacuate the victim. The agents can communicate in order
to find a partner with the complementary skill. Each agent has a field of perception
that limits its perception of the environment. A medical porter is able to perform one
of the following actions in a time cycle of simulation: 1) the action move randomly ,
2) the action move towards a location , 3) the action wait , and 4) the action evacuate
a victim .
We use this application along the paper to illustrate our study of the cost of the
environment supporting interaction and simulation.
1 http://education.mit.edu/starlogo/