How complex an agent?

[Sven N. Thommesen]

All,

in designing the sim for my dissertation, I'm trying to come up
with a gross classification of agent behavior, based on how complex it is.
My advisor wants a 'full-circulation' model (i.e. an agent version of
General Equilibrium), and I'm thinking that in such a model it may not be
necessary that *all* agents be supersmart optimizing agents. Perhaps,
depending on the question being asked, some of the agents can be of the
'cardboard' variety -- just there doing their job to pass money and goods
along as needed.

(In fact, even in a full blown model we wouldn't want agents to be as smart
as assumed in the usual rational-expectations economic model, since those
models assume way too much knowledge on the part of agents.)

It also seems like good software design ('stepwise refinement') to not
create all agents as complex as possible from the start, since this makes
it difficult to verify the model. (To verify the operation of one class of
agent you want everything else to be as simple as possible, to avoid
artifacts.)

Anyhow, I offer up the list below of agent behaviors, in order of
increasing capabilities, and invite your comments or criticism.

Thanks!
Sven Thommesen

Level 0: agent performs the same act(s) every period [e.g. leaves the same
amount of influence on the world grid], or responds the same way every time
to messages from other agents.

Level 1: as above, but response is contingent on variables in the agent's
current state.

Level 2: as above, but action/response is also contingent on data collected
        a) from the agent's local neighborhood;
        b) from globally available data.

Level 3: as above, but give the agent MEMORY; it collects data (detail or
summary) each period and current action/response depends on this memory data.

Level 4: as above, but give the agent a GOAL, a function or criterion to be
MAXIMIZED.

Level 5: as above, but give the agent EXPECTATIONS over the future state of
its world; many different expectations formation schemes are possible.
Allow the agent to act so as to seek its goal (maximize its maximand) over
expected futures.

Level 6: as above, but add adaptation or a learning mechanism.




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