Writing a solver for Net

I had mail yesterday from a computer science student asking how I went about writing the solver for the game Net in my puzzle collection. I took the question literally, i.e. not just ‘what is the algorithm?’ but ‘what was your thought process that allowed you to come up with the algorithm?’. I thought that was a good question, and so I wrote a fairly complete answer.

Having done that, of course, it seems a shame to only send it to a single recipient! So I'll post it here as well, in case anyone else is interested.

( long description )