Information Technology Reference
In-Depth Information
They conclude by stating that their model incorporates five im-
portant aspects, which are usually not all handled in other models: a
dynamic world with events, actions of observation, actions with dura-
tion, group- and individual actions, incorporation of true concurrency.
On the positive side, De Vries et al. provide a well-defined model
that takes care of a lot of problems encountered in other approaches.
A very important aspect is that they distinguish between 'a local
semantics for individual agent programs and a global semantics which
composes the local behaviours of the agents and events happening
in the world into a global system behaviour' [30]. On the other
hand, they restrict the agents to the iterated execution of some
behavior specification and use a time-stepped execution with fixed
time increments. The disadvantage of this approach is that all parts
of the model (i.e., agents and environment) have to be described using
the same level of granularity, which will not be optimal in all cases.
Furthermore, this leads to a very close coupling of model components
and thus complicates the reuse of these components within other
models. Another negative aspect of this approach is that modeling
issues (behavior of the agents) are coupled to execution issues (time
steps of fixed size) which limits adaptability, flexibility and reuse.
Ke, Hu (2006)
Ke and Hu point out that 'concurrent behaviors turn out to be
very important under the multi-agent system circumstances' [66].
They furthermore point out that the approach of De Vries et al.
does not contain 'solutions to the non-deterministic and behavioral
conflicts induced by true concurrency' [66]. Therefore, they present a
concurrent agent model aiming at the characteristics of concurrent
behavior in multi-agent systems. In sharp contrast to the models
presented in the previous sections, the model of Ke and Hu is based
on ideas of the fields of modal and temporal logic.
Somehow similar to De Vries et al. the model of Ke and Hu makes
use of two distinct time scales: macro-time and micro-time. In their
model, an action's duration endures at least one macro-time segment.
Search WWH ::




Custom Search