"Did he accept the warning upon himself?" - The offender must be apprised of the particular form of execution he will suffer if he commits the prohibited act. Furthermore, he is not executed unless he declares that he plans to do the action, even though he knows that doing so will result in his execution.
"Did he kill within as much time as needed to say a greeting of peace to one's teacher?" - If he commits the offense after this period has elapsed, he avoids punishment since, perhaps in the interim, he has forgotten the warning.
Art: The Execution of the Emperor Maximilian by Edouard Manet