Yesterday Blake and I drove to Metron's branch in San Diego and I met for the first time four of the main project participants: John Foley (math), Thy Tran (programming), Tom Mifflin and Chris Boner (two higher-ups involved in the project). We got a briefing on how Metron's [ExAMS]( software works. It lets you design complex systems and view them in various ways.

The most fundamental view is the "activity trace", which consists of a bunch of parallel rows, one for each "object", going left to right in time. Each row has a bunch of boxes showing "activities" that are connected by wires when one box activity can only occur after another. "Time" here is not numerical but just a partial ordering on activities. The wires can also interact via logic operations, e.g. activity A may occur iff B and C but not D occur. Thus, the wires also interact via logic gates. However, these gates may also involve "delays", e.g. A occurs 10 minutes after B occurs.

One can zoom in on this activity trace, seeing more fine-grained descriptions of the activities: that is, boxes within boxes.

All of this gives a "logical" description of the complex system being described. There is also a much more complicated "physical" description, saying the exact mechanical functioning of all the parts. These parts are described using "plugins" which need to be carefully described but can then simply be _used_ when assembling a complex system.

We are supposed to be designing our own systems using operads, but we want to take advantage of the fact that Metron already has this working system, ExAMS. Thus, one thing I'd like to do is understand ExAMS in terms of operads and figure out how to do something exciting and new using this understanding. I was very happy when Tom Mifflin embraced this goal.

Unfortunately there's no manual for ExAMS. Luckily it seems fairly simple, at least the part that I care about. (There are a lot of other views derived from the activity trace, but I don't need to worry about these.) Also, ExAMS uses some [DODAF standards]( ) which I can read about. Furthermore, in some ways it resembles [UML]( and [SySML](, or more precisely, certain _parts_ of these languages.

So, I plan to put some time into understanding the underlying math of these activity traces.