More than a hundred years ago, Kempelen, with his famous “Mechanical Chess Player,” not only defeated the strongest chess players who dared challenge him, but also liked to create chess problems that frustrated the greatest minds of the time. This is one of the most difficult among those problems.
Game: The task is to place four black queens and one black bishop on the chessboard so that there is no square not under their attack. In other words, after arranging the five black pieces, it must be impossible to place the white king anywhere without it being in checkmate.