Japanese car maker on some self driving car technologies. I remember him giving a specific example of an unsolved problem that they were working on to be able to differentiate between hazardous things like a car stopping short in the road in front of you (which would require you to slam on the brakes) with a car slowing down to make a right turn where they will be out of your way before you get there (which doesn't require you to slam on the brakes). From the environment that they were working in, those cases were very hard to distinguish.