Cooked Endgame Studies

Since many composed endgame studies deal with positions that exist in tablebases, their soundness can be checked using the tablebases. Some studies have been cooked, i.e. proved unsound, by the tablebases. That can be either because the composer's solution does not work, or else because there is an equally effective alternative that the composer did not consider. Another way tablebases cook studies is a change in the evaluation of an endgame. For instance, the endgame with a queen and bishop versus two rooks was thought to be a draw, but tablebases proved it to be a win for the queen and bishop, so almost all studies based on this endgame are unsound. - Wikipedia Article