Active Index System
The Active Index is an extended Petri net model.
Instead of having fixed connections between
places and transitions, the active index allows
index cells to be instantiated as they
Therefore, one index cell can send a message to another
index cell type. If no appropriate index cell instance exists,
an index cell will be instantiated.
For example, if an enumerator index cell wants to
create several hundred solution index cells,
it can send messages to instantiate such solution
In what follows, we will first give the formal
definitions of an active index cell, and
then present an example of a simple active
index system for distance learning.