If player 1 places an X in a corner, player 2 must place an O in the center; otherwise, player 2 will lose. For example, if player 2 puts the first O in the corner opposite the first X (see fig 5), player 1 should place an X in any remaining corner, thus forcing player 2 to put an O in between the two Xs to prevent player 1 from winning. Player 1 can then win by placing an X in the last corner. Readers can figure out how to win the game if player 2 has chosen to put the first O somewhere other than the center square.