help in brahms

[Habtamu Tkubet]

is it possible to have several activities (work frames) in parallel?

[Maarten Sierhuis]

Dear Habtamu,

Please specify what you mean exactly with "several activities in parallel?"

I can see a couple of meanings:

1) Two or more agents are executing workfames/activities at the same time.

2) One agent is executing two or more workframes/activities at the same time.

Ad 1) In this case, each agent's workframes/activities execute at the same simulation clock tick (i.e. at the same event time). This can certainly be done, and, as a matter of fact, is done explicitly. Each agent has its own reasoning engine.

Ad 2) For one agent, an agent can "perform" multiple activities at the same time, HOWEVER, just as in the Unix operating system (i.e. time sharing), only one workframe/activity can be active at each (simulation) clock tick. What happens is that if two workframes/activities are executing at the same time, it means that both their preconditions evaluate to true. The BVM uses activity priority to determine which workframe/activity should be executing at each event. The other workframe/activity will be put in an "interrupted" state. When the first activity ends, the "interrupted" activity will become the active activity. This is based on the notion that a person do not perform "independent" activities at exactly the same time, they timeshare the activities.

To model activities in "true parallel" mode, you have to either use two agents, OR, model the activities in a hierarchical manner. To do this you model this using a composite activity. What this means is that the higher-level activity (composite activity) has a lower-level activity (primitive or composite) being executed at the same time; for example, walking while talking on the phone. In that case walking could be the composite activity, and talking on the phone is a "sub-activity" that can be performed, while you are walking.

I hope this helps you.

Maarten Sierhuis.