I studied “computation” at Oxford 92-95 while CAR Hoare was still there and basically all they taught us about computers were these formal methods. They actually thought it would revolutionise programming and looked down at anything else as “hand-waving”. Think the syllabus was abandoned only a few years later thank goodness.
Actually it goes straight back to the Apple TV remote without having to unlock. Not sure what the time limit is but it works after the device has gone to sleep and otherwise locked itself.