Temporal reasoning

The relationships between two events in time can also be absolute or relative. Some relationships epecify an exact amount of time that must come between the two events: ten minutes after the plastic has been poured, remove the widgets from their molds. More common are the simple relative relationships which just specify that one task must follow another. In between are tasks that are related by some interval: to ensure unwrinkled clothes remove them within an hour of the dryer finishing.