On August 22, 2025, version 6.15.58 has been released. Among other things, this version allows the user to discover two types of additional places: occurrence places and equivalence places.
We use the event log pdc2024_00000100.xes from the PDC 2024 data set to explain the additional places. First, we show the original model, that is, the model that was used to generate this log.
From this model, we learn that the activities t3, t6, t9, t10, t27 and t28 each appear twice. Most notable, we see that the concurrent block now contains two branches with t27 followed by t28, and that t3 can be executed twice in a trace, where this does not hold for t4 and t7, which still need to be executed exactly once (like t1).
Second, we show the model discovered when allowing for the additional places.
This model contains 10 additional places:
- The two occurrence places for t27 and t28. Each of these places contains initially two tokens (not shown in the image) and are not contained in any final marking, which effectively captures the fact that both transitions need to be fired twice.
- The two equivalence places between t27 and t28, where the place from t27 to t28 contains initially no tokens and the place from t28 to t27 contains initially two tokens (not shown in the image). This effectively captures the facts that t27 and t28 need to occur equally often, that any t28 is preceded by a t27, and that we can have two times t27 followed by two times t28.
- The six equivalence places between t1, t4 and t7, where the place from t1 to t4 or t7 contains initially no tokens and the other places contain initially one token. This effectively captures the facts that t4 and t7 occur equally often as t1, that both t4 and t7 are preceded by t1, and that t4 and t7 can occur in any order. These places alleviate the problem caused by the fact that t3 appeared twice in the original model.
As such, using these additional places, undesired behavior of the discovered model can be prevented. For the “Xcavate Petri net (user)” plugin, these places contributed to achieving a new high score on the PDC 2024 data set of 92.9%.
By default, these additional places will be discovered. To change this behavior, the user can run the “DiSCover Petri net (user)” plugin, uncheck the corresponding check boxes in the “Select conversion settings” dialog, and then select the Finish button.
This will set these settings as default for the “DiSCover Petri net (user)” plugin, which will be used by the “Excavate Petri net (user)” plugin.
Note that adding equivalence places uses a play-out of the model (without any additional places added) to prevent adding redundant equivalence places (like between t1 and t2).