Michael Levin

So the first thing I decided to do, and this is the work of my student Taining Zhang and then Adam Goldstein on this paper.

This goes back to our original discussion about putting a barrier between it and its goals.

And the first thing I say, okay, how do we put a barrier in?

Well, how about this?

The traditional algorithm assumes that the hardware is working correctly.

So if you have a 7 and then a 5, and you tell them to swap, the lines swap the 5 and the 7, and then you go on.

You never check, did it swap?

Because you assume that it's reliable hardware, okay?

So what we decided to do was to break one of the digits so that it doesn't move.

When you tell it to move, it doesn't move.

We don't change the algorithm.

That's really key.

We do not put anything new in the algorithm that says, what do you do if the damn thing didn't move?

Okay.

Just run it exactly the same way.

What happens?

Turns out something very interesting happens.

It still works.

It still sorts it.

but it eventually sorts it by moving all the stuff around the broken number.