Merge branch '185-process-tree-model-description-for-llm-purposes' in…

…to 'integration'

[Priority 2] Process tree model description (for LLM purposes)

Closes #185

See merge request process-mining/pm4py/pm4py-core!1178

pm4py/objects/process_tree/obj.py

@@ -175,6 +175,21 @@ def __str__(self):
         """
         return self.__repr__()
 
+    @staticmethod
+    def model_description() -> str:
+        descr = """A process tree is a hierarchical process model.
+The following operators are defined for process trees:
+-> ( A, B ) tells that the process tree A should be executed before the process tree B
+X ( A, B ) tells that there is an exclusive choice between executing the process tree A or the process tree B
++ ( A, B ) tells that A and B are executed in true concurrency.
+* ( A, B ) is a loop. So the process tree A is executed, then either you exit the loop, or you execute B and then A again (this can happen several times until the loop is exited).
+the leafs of a process tree are either activities (denoted by 'X' where X is the name of the activity) or silent steps (indicated by tau).
+An example process tree follows:
++ ( 'A', -> ( 'B', 'C' ) )
+tells that you should execute B before executing C. In true concurrency, you can execute A. So the possible traces are A->B->C, B->A->C, B->C->A.
+"""
+        return descr
+
     def _get_root(self):
         root = self
         while root._get_parent() is not None: