polling.xml is a eDSPN file that contains a PN representing a polling system. 
A single server attends two queues of customers.

pollingExperiment.xml is a PN-Ex file that contains an experiment consisting 
of increasing the number of both queues by one unit until the system reaches 
(or gets close to) its maximum throughput.

pollingExperimentResults.xml is a PN-Ex results file which contains the results 
you will obtain if you run the experiment on the polling system PN.