To operate effectively in open environments agent systems must be adaptive.
The RETSINA agents have been designed explicitly to be adaptive.
Adaptation is behavior of an agent in response to unexpected
events or dynamic environments. Examples of
unexpected events include the unscheduled failure of an agent, an
agent's computational platform, or underlying information sources.
Examples of dynamic environments include the occurrence of events that
are expected but it is not known when (e.g., an information
agent may reasonably expect to become at some point overloaded with
information requests), events whose importance fluctuates widely
(e.g., price information on a stock is much more important while a
transaction is in progress, and even more so if certain types of news
become available), the appearance of new information sources and
agents, and finally underlying environmental uncertainty (e.g., not
knowing beforehand precisely how long it will take to answer a
In RETSINA, adaptivity is exhibited at multiple levels, from the
application level of interacting agents down to selecting different
individual method executions based on changing conditions.
Thus, in RETSINA, the following types and levels of adaptivity have been implemented