>Basically the perfect player should play perfectly, but prolong the game as much as possible.
hmm no, "masters" will concede the game when they realize they lost, if conceding isn't an option I believe making a play that will end the game faster is the next best.
One reason for prolonging the game is that it gives your opponent more chances to make mistakes, turning some losses into either ties or victories. This is true for both human or AI opponents.
Another reason to prolong the game against human competitors is if you're playing another game after this one, and you think your opponent will tire before you will. By causing the game to go longer, you gain a mental advantage in the next game.
Now, these may be considered "unfair" or "unsportsmanlike", but explaining that is left as an exercise for the reader.
hmm no, "masters" will concede the game when they realize they lost, if conceding isn't an option I believe making a play that will end the game faster is the next best.