Section 3 - Agents and some user facilities

3.2 Time levels and the container hierarchy

The idea is that the separate producer and consumer agents will be contained in the model agent. So the whole set up can be pictured like this.

Thus we have a third hierarchy in SDML (sorry) - a hierarchy of containment. Such containment also helps determine the order in which rulebases fire. The general principle for containers and timelevels is:

The initial and content rulebases of the container fire before the corresponding rulebases of its contents for each timelevel. The final rulebase of the container fires after the final rule base of the final rulebases of its contents.

So with only the eternity timelevel the order would look like this.

If the time level involved was looping you would go back round a loop from the sub-agents' content rulebase to the universe's content rulebase several times. You can imagine how complicated the complete diagram for sub-agents plus several looping time levels would be! This can seem very confusing, but usually in each context you only have to worry about a few rulebases at a time.

It is important to note that when agents fire their rulebases in parallel they can not access the results of any other agents rules until a subsequent time stage. Thus if you were to simulate one agent communicating with another and then the second agent taking some action dependent on this you would need more than one time stage to do this.

An introduction to SDML - Bruce Edmonds - 13 JUL 99

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