 the game is played as follows. First, player 1 picks out an individual \(a\), whereafter player 2 chooses an individual \(b\). Then player 1 proceeds to choose a further individual \(c\), to which player 2 responds by picking out an individual \(d\). Thereby a play of the game has come to an end. The tuple \((a, b, c, d)\) of individuals chosen determines the winner of the play. If the quantifier-free formula \(R(a, b, c, d)\) holds in \(M\), player 2 wins, if not, player 1 wins.