Yose Problem
British Go Journal No. 20. July 1973. Page 8.
J. T. Fairbairn
Problem |
- Question 1
- Black to play. What is the result if correct yose are played?
- Question 2
- White to play. What is the result if correct yose are played?
- Question 3
- Count the number of points for each individual yose play.
- Question 4
- What is the largest move?
- Question 5
- What is the smallest move?
(Assume that there are no stones already captured by either side.)
Answers
Diagram 1 (Black to play) |
- Black 1 is tesuji and obviously the largest move.
- White 6 cannot be omitted. The reason it cannot be one line higher is that black could then play the atekomi A.
- Black 7' should not here be at 12. Both points are gote but black 7 leaves the threat of going one point below 12.
- White can play the kikashi moves of 8 and 10 in sente.
- White 12 ispreferred to 13 or 14 because of the threat from black 7.
- Confirm that because of black's atekomi 15, white must later play B.
- White 18 is the last move.
Black's territory = 26 points,
White's territory = 26 points.
Result = jigo.
Diagram 2 (White to play) |
- White 1 and 3 are kikashi. You should be aware of the necessity of playing all sente kikashi moves before playing the largest gote move in yose.
- Black 2 and 4 are inevitable. This black group would die if black were to turn to the large yose in the top left-hand corner.
- White 5 is the maximum gote yose. It s also big because it prevents black's sente yose of the previous diagram.
- Black 6 is sente.
- Black 8 and White 9 are also maximum moves.
- Black 14 is 1 point because it forces white A later.
When Black completes the game by taking the half-point ko at 18 and
connecting at 11, his territory, including captured men, is 23 points
and White's is 30.
Therefore White wins by 7.
Diagram 3 (Q3, 4 & 5) |
- Black A is worth 8 points and therefore white B which prevents this is also worth 8. (This figure is obtained from the sum of the differences between Dia 1 and Dia 2.)
- C is worth 5 points, but if white answers immediately as in Dia 2, it is worth 2 points in sente.
- D is 2½ points, or in other words, if white continues 1 line further, black will have to take off white and fill in one point of his own teritory.
- E equals 1 point in sente because white can play to the left of E later.
- F is one point in sente, G 1 point in gote and H 2/3 point.
On the basis of the above calculations, the answers to questions 4
and 5 are:
Largest move, black A or white B;
Smallest move, yose H.
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