British Go Journal No. 64.  March 1985. Page 10.
Francis Roads explains the problems on the previous page  (please solve them yourself first).
Diagram 7 |
Positions in which Black does not gain a great advantage by playing at A in Dia 7, and preventing White from doing so, are very rare.
Diagram 8 |
The extension to B in Dia 8 is always a good move when Black has made the high fourth line shimari (enclosure) as shown. When at the same time it prevents White from making his ideal extension to the same point, as here, it is doubly valuable.
In a minority of cases C is the better move. Both B and C are still excellent moves is one or both players have made a low shimari, eg if the marked black stone were at D or E instead.
Diagram 9 |
This is the well known "crane's nest". Black can capture three white stones, thus connecting all his own together, if he is prepared to sacrifice a stone at F in Dia 9. The rest of the sequence is left for you to work out!
Diagram 10 ||
Diagram 11 |
If your answer was I in Dia 10, you were hoodwinked. White can kill you with the hane at K, followed by J if you defend at L. Black can now capture both J and K, but not in such a way as to make two eyes.
The only way to live is with J in Dia 10. Dia 11 shows the worst White can do, leading to a seki (stalemate) after White 5. But as he has to give up sente to take just five points of territory from Black, and as Black 2 and 4 may help to reduce some outside white territory, this is very much an endgame sequence.
Incidentally, this position is discussed in Chapter 9 of "Life and Death" by James Davies. All you people who waste your time trying to memorise joseki would do far better to memorise as much of that book as you can.
Diagram 12 |
By now you will have spotted that the theme of this article is symmetry. All the solutions so far have beem examples of the Go proverb "If the formation is symmetrical, play in the centre" ( see "Go Proverbs Illustrated" by Kensaku Segoe, p50).
You may therefore have chosen M or N in Dia 12 as your solution. If you did you were hoodwinked again. This position is the odd one out. By playing asymmetrically at O or P, Black easily links his two eyes together and all his stones are alive.
If he starts at M, White sacrifices a stone at O. Black can then save only one half of his group with the sequence Q, P, N, R. If he starts at N, he can again save half, or fight a ko for the whole group after white Q, black O, white R, black P, White takes ko at M.
Diagram 13 |
This is the famous classical problem from "Iwami Jutaro's prison break". Mr Jutaro escapes with the symmetrical move S in Dia 13. The rest is left to your investigation.
A broader discussion begins overleaf .