Someone on LambdaMOO created a version of the “Leap of the Locusts” puzzle, which can be described as follows:

The puzzle consists of a board with holes for nine pegs. There are eight pegs, initially arranged as GGGG-YYYY, and the goal is to have the board look like YYYY-GGGG (swapping the green and yellow pegs). On each move, a peg may move either one or two positions into the empty space; green pegs may only move to the right, and yellow pegs may only move to the left.

Instead of solving this manually (it’s really not that hard) I decided to program my Protocol Explorer to solve it. I found one small bug in PX, which I fixed, and then it found a solution in approximately nothing flat. I’m so proud of my child. :-) Anyway, I’ve added the description file to my list of PX examples.