When the pawn is too far up for the Philidor defence, put your king on the short side of the pawn, the side with fewer files to the edge. That leaves the long side for your rook, which checks from the side. It has to be at least four files from the pawn, so the enemy king can't walk up to it and stop the checks. With your king on the long side instead, your rook has no room and the pawn promotes.
Every move is checked with an endgame tablebase, which knows the exact result of every position with up to seven pieces. The computer defends perfectly, and if a move throws the result away, the trainer stops and shows you a better one.
