> I suspect that both these programs could be expanded to the full rules without making them a lot bigger, by taking the short cut of allowing the human to make

> I suspect that both these programs could be expanded to the full rules without making them a lot bigger, by taking the short cut of allowing the human to make those moves, but not the computer Ah, but, for instance, what if the only remaining move for the AI was to use the en passant rule, for instance? By not invoking the rule, the AI would not be playing chess by the book.