One of my acquaintances bought herself a vacuum robot. This robot was supposed do its job during the night, when all residents of the house were asleep. But that was not the case. While the human inhabitants lay in their beds on the upper floor, there was no sleep to be thought of among the animal housemates down stairs. The cat had declared the new device to be its mobile coaster. The old dog walked through the rooms, annoyed and grumbling. And the mice finally had a clear path now, because the cat had no more time for her actual job. In the meantime, my acquaintance has intervened and changed the chronology: The robot now runs in the morning when the cat is asleep and the dog is outside. And the mice invasion has disappeared again quickly.