Just 3 months ago they said they replaced successfuly humans with AI.

https://news.ycombinator.com/item?id=42432494

this works only for a while

what?

Two positions per finger, three for the thumb. If you are feeling dexterous, you can count to 48.

Hmmm, still to be discussed I am not sure if the accepted answer is the right one.

I think for those superusers mentioned in the article the invested energy surpasses the benefits and biologists have a word for that too.

I think there is a greater psychological issue here at stake, a hidden game where outliers and performers turn into sadistic trolls.

I tried to take a better look at the phenomenon in this blog post: http://flopinson.blogspot.com/2014/08/mass-trolling-in-arena...

What if it encounters a dolphin a net or another sub?

bad things. This is much more practical for torpedoes. In fact you would almost call those missiles at that point. Yup, it appears that is already a thing: http://en.wikipedia.org/wiki/List_of_supercavitating_torpedo...

You use Ask HN to post a link, smart.

No trickery intended here, just seemed to be the best way to go about it.

The answers in the OP don't seem to be exhaustive enough.