Chess engines haven't needed book moves fed to them for a very long time now. Start up any modern engine and let it analyze, and it will only be considering str

Chess engines haven't needed book moves fed to them for a very long time now. Start up any modern engine and let it analyze, and it will only be considering strong theoretical main lines from the first second. That said, they have been trained almost exclusively on games that started from the normal starting position. But then, so have humans.