Ropero et al. Figure 3. PDDL predicates definition following an equal PDDL and timeline-based formulation for a cooperative hybrid UGV-UAV example. state. We use a particular naming convention which allows PDDL-Lib to identify PDDL actions as tokens on their specific state variables. Notwithstanding this naming, we have not reached a complete translation of the PDDL domain file, due to semantic differences that we have not considered yet, for instance, the effects and conditions of every action. Thus, we only can guarantee a translation for simplified domain formulations. Currently, we are able to translate the PDDL predicates and temporal actions as tokens belonging to state variables as follows: - A PDDL predicate follows the format (StateVariable_Predicate A1 :::An ). PDDL-Lib translates it as the token Predicate with the attributes A1 :::An belonging to StateVariable. Figure 3 shows an example of such formulation. - A PDDL temporal action is named as (:durativeaction StateVariable_Action). PDDL-Lib translates it as the token Action belonging to StateVariable. Figure 4 shows an example of this formulation propagation in a PDDL domain file. The effects file has been devised to allow PDDL-Lib to understand the actions plan generated by the PDDL Planner, and to build a timelines plan following the naming imposed by the domain file. As we are unable to guarantee a complete translation from the PDDL domain file, we need the effects file to define an effect Figure 4. PDDL temporal actions definition following an equal PDDL and timeline-based formulation for a cooperative hybrid UGV-UAV example. MARCH 2019 IEEE A&E SYSTEMS MAGAZINE 45