CPN Hierarchy supports a method for defining sets of places so that anything that happens to each place in a set also happens to all the other places in the set. The places are then functionally identical. Such places are called fusion places, and a set of fusion places is a fusion set.
Fusion adds nothing fundamentally new. If all the members of a fusion set are on the same page, we could replace the set with a single place and connect to it all the arcs that are connected to any member of the set. If the members are on different pages, we could copy everything on the several pages to a single page, and again collapse the set.
Conversely, if a net contains a place that has many arcs connecting to it, or requires very long arcs to reach it, we can unfold it into several places, on the same or different pages, and so simplify the net’s graphical structure without changing its meaning. Such unfolding is a common event during the process of CP-net development. Frequently the need for it can be anticipated, and fusion places can be used from the beginning.
In the current version of CPN Tools, it is only possible to add a place to a fusion set if the place is neither a socket nor a port. Read more about the hierarchy limitations of CPN Tools.
Creating fusion places
After applying the tool, a fusion tag is added to the place. The tag is set in a default position with a default name for the fusion set.
The tag can be repositioned, and the name of the fusion set can be changed by editing the text in the fusion tag.
Members of a fusion set
The members of a fusion set can be located by placing the cursor over a fusion tag. An aqua aura indicates which place the fusion tag belongs to. Pink auras and highlights indicate other places in the same fusion set and the pages which contain these places.
Fusion sets across multiple pages
Fusion sets may contain places from several different pages.
Multiple fusion sets
Each net may contain multiple fusion sets.