Pgen is the old Specman constraint solver, and IntelliGen is the new one. Until version 10.2 you
need to select IntelliGen using a config flag (set_config(gen,default_generator,IntelliGen) before you
load you code. Starting with 11.1, IntelliGen will be the default solver, so you only need to change
the config if you want to use the old one (Pgen).
The big difference (which you have already worked out) between Pgen and IntelliGen is that in
Pgen the solver looks at one field at the time. In IntelliGen all fields (no matter in which point of
the environment hierarchy they are) which are related via constraints are solved together. Doing so
can modify the order in which postand pre_generate() are called (this is what is described in the
It appears that you have many questions on the generator (there are some other posts from you).
Maybe it would be helpful to get in touch with Cadence and try to arrange some on-site support
for a couple of hours with a local AE to solve your issues.