Assumptions

[albore]

From Smith & Weld, 1999 (i.e. deterministic actions of fixed duration):

• The effects are realized at some unknown point during action execution, and thus can be used only once the action has completed.
• The preconditions must hold at the beginning of an action.
• The preconditions not be deleted by the action itself must hold throughout the duration of the action.

From PDDL2.1 Fox & Long, 2003:

• The preconditions may need to hold instaneously before the start (at start), before the end (at end) or over the complete execution of the action (over all).
• The effects are realized instantaneously either (at start) or (at end), i.e., at the beginning or the at the completion of the action (respectively).

From Mausam & Weld 2007:

• All executing actions terminate before the goal is considered achieved.
• An action, once started, cannot be terminated prematurely.

From Dvorák et al 2014:

• The action must always occur in the time interval of its parent action, its parameters are bound to the values defined in the parent, if any.