Generate the stoichiometry (|u| by |v|) matrix for the SPN.
Each column gives the net effect of that transition firing upon the state
space of the model. Internally, this creates a Pre (
spn_Post) matrix, and then calculates the final stoichiometry.
set of places (P) (see details)
set of transitions (T) (see details)
The set of transitions (
spn_T) is generated from one of the following: