British Go Journal No. 66.  November 1985. Page 27.
Part 1 is on page 22 .
Figure 4 ||
Figure 5 (29-37)|
Fig 5. Both A and C in Fig 4 are sente for white (black must answer), so black prevents on of them with 29 (a 'reverse sente' play), gaining the three points marked . White then plays his sente sequence 30 - 33, which gains him three points, the one marked and two for forcing black to play 31 and 33. Why does black choose 29 rather than D in Fig 4?
The reason is that 29 threatens to take a further two points from white. If black were to play at 34, white E, white still needs to play one extra move within his territory. SO white 34 and black 35 - 37 are both worth two points and the result is a draw, both sides have 26 points.
This game illustrates the benefits that even stronger players can derive from 9*9 Go. It is excellent practice in the endgame.
It encourages you to think not only about finding the next largest move, but in terms of the optimum sequence of moves - the pros and cons of 'small' sente versus 'large' gote plays, and so on. Often it is possible to count carefully and work out the correct sequence right down to the last move.
Of course, this is something that professionals can do on a large board, almost from the middle-game.