Limit number of paths in a candidate for teacher

dtree_teacher_base.py

@@ -123,6 +123,10 @@ class DTreeGurobiTeacherBase(GurobiTeacherBase):
         conjunct_list = list(self._candidate_to_conjuncts(candidate))
         #TODO ANGELLO: add check if too many conjunctions
         print(f"Number of conjuncts:  {len(conjunct_list)}")
+        if len(conjunct_list) > 20: # TODO: make this a parameter to the class
+            self._reason_unknown = f'(too many paths {len(conjunct_list)} in candidate {candidate})'
+            return z3.unknown
+
         print("Checking candidate", flush=True)
         for conjunct in conjunct_list:
             # print(".", end='', flush=True)