Problem No. 120 from Igo Hatsuyoron
By Inoue Dosetsu Inseki (1646 - 1719)
Black to play and win |
Black to play and win |
Dia. 67p.1: B 67 - W 76 |
B 67: This seems to be the last possible moment to play that "bad shape"-move in the upper right before action starts on the left side of the board. W 68: White starts the "usual" sequence on the left side, because answering immediately in the top right will lose White the game, as we have seen already (please refer to the variation for B 93). Update 2011: Without second Throw-in, White will get the closest result, when she prevents two Black eyes immediately with a move above 67. Update 2009: To start attacking the black stones on the left with 68 is alternative "L" of the research on my "bad-shape" move. Perhaps a White answer in the top left corner would be stronger. Update 2011: In the meantime we found that White's answers in the top left corner do not favour White, as we supposed before. B 73: Black now takes the opportunity to live in the top right. Black will not be successful if he returns to the Main Path here. [ see variation ] Saving the stones on the left may look big, but will lose the game for Black. [ see variation ] W 76: |
Dia. 67p.2: B 77 - W 86 |
B 77, 79: Black answers in the top left, getting points while threatening the second eye of the White centre group. B 81: What follows is an amateurish idea of the Endgame. Black seems to be about five points ahead. Update 2009: B 85: A Hasami-Tsuke at 86 will give Black a further advantage of one point. |
Dia. 67p.3: B 87 - W 96 |
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Dia. 67p.4: B 97 - W 106 |
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Dia. 67p.5: B 107 - W 116 |
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Dia. 67p.6: B 117 - W 126 |
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Dia. 67p.7: "The Score" |
Black wins by 6 points. Black may perhaps be 1 point better if he does not play the second Throw-in with B 19. The Seki in the lower right is not resolved, so this proves as a lost move now. |
Dia. 67p.16: B 73 - W 82 |
B 73: Black saves his stones on the left side. W 74: White deprives Black of two eyes on the right side. B 75: So Black has to return to the Main Path again. B 81: Necessary to prevent two eyes for Whites left side group. W 82: White can enter Blacks weak top left corner now. |
Dia. 67p.17: B 83 - W 92 |
B 83: Black cannot give up his stone in Atari. |
Dia. 67p.18: B 93 - B 97 |
B 95: If played at 96 (see below), there will result a "normal" Ko, this will be won by White, too. |
Dia. 67p.19: W 98 - B 99 |
W 98: White starts a Double Ko that Black cannot win. |
Dia. 67p.20: W 100 - B 103 |
B 103: Sooner or later Black has to capture that White stone in the corner. |
Dia. 67p.21: W 104 - W 108 |
W 108: White lives in the top left and therefore wins the game by a large margin. |
Dia. 67p.22: W 76 - B 85 |
W 76: White starts the endgame in the upper left before returning to the Black group on the left with 84. B 85: The moves from here on follow the suggestion of Yoon Young-Sun 5p from Korea, now living in Hamburg, Germany. Special thanks to Yoon Sensei, who was so kind to help me with the correct Endgame here. |
Dia. 67p.23: W 86 - B 95 |
W 86 - 94: It does not profit White to Tenuki with one of these moves to play in the centre. [ see variations ] Update 2009: B 89: A Hasami-Tsuke at 90 might be possible and give Black a further advantage of one point. |
Dia. 67p.24: W 96 - B 105 |
B 103: The biggest point remaining on the board. W 104: Sente. The follow-up move at A would be unbearable for Black. |
Dia. 67p.25: W 106 - B 115 |
W 114: It is the correct order of moves to play here first and then at 116. |
Dia. 67p.26: W 116 - B 125 |
B 119: Hereafter only 1-point Endgames are available. B 121: It would be a mistake to follow the Main Path instead. The captured White stone compensates for the point Black has lost below. [ see variation ] |
Dia. 67p.27: W 126 - B 131 |
W 130, B 131: No Ko fight will start here, because two Ko of different colours are open. |
Dia. 67p.28: "The Score" |
Black wins by 1 point. Black may perhaps be 1 point better if he does not play the second Throw-in with B 19. The Seki in the lower right is not resolved, so this proves as a lost move now. |
Dia. 67p.22: W 76 - B 85 |
W 76: Yamada Shinji's Tsuke is not possible here. B 77: This black answer threatens to connect the string of black stones to the outside and is absolute Sente. W 82: Is no threat any more against the right part of Black's stones, so Black can answer with 83 in the corner. Should White play at A instead (what she did in the Seki-sequence after Black 83, White B, Black C), she will lose the Semeai by at least one move. White has lost the Sente move of B (77 had been white, not black), which forced Black to take himself one liberty by connecting at C in the Seki-sequence. Black wins the game. |
Dia. 67p.29: W 86 - B 91 |
W 86: If White plays in the centre, she has this 8-point Endgame, according to Yoon Sensei. B 87: But Black gets much more profit in the upper right corner. |
Dia. 67p.30: W 88 - B 91 |
W 88: White is unable to capture some Black stones in the centre. |
Dia. 67p.31: W 88 - B 89 |
B 89: This Endgame in the top right corner is worth about 12 points for Black. So White is 4 points worse. |
Dia. 67p.32: W 90 - B 99 |
B 91: This Black Endgame in the top right corner has a value of 8 points, too. So the result remains unchanged. |
Dia. 67p.33: W 92 - B 99 |
B 93: Again, the Black Endgame in the top right corner has a value of 8 points. So the result remains unchanged. |
Dia. 67r.1: |
For research purposes we can divide the board into four areas and look at these one after another. Lower right (light brown): If the big Black group on the right gets two eyes, the temporary Seki will remain unresolved until the end of the game. Upper right (light yellow): White will not get additional points here. Lower left (orange): It is possible for Black to save his five stones on the left edge. And the end of this procedure the two Black stones on the fourth line perhaps might be in danger of being captured. Upper left (yellow): This is the most interesting (and most difficult) area. To win the game, White must destroy Black points in the corner and get own points in such an amount that can compensate for the loss in the lower left quadrant. Precondition of this research is: With 68 White plays a move that forces Black to make two eyes for his upper right group and at the same time threatens the upper left Black corner. |
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Dia. 67r.2: |
According to Yoon Young-Sun (please refer to her endgame suggestion), each of the Black Sente moves in the top right corner (71 to 79) would threat to capture some White stones (with the side effect of providing Black with his second eye). So they could be played - if necessary - before securing the second eye inside the Black eye space with 81. Update 2009: Perhaps Black can play 75 at 76, what is one point better for him. Update 2011: Our thoughts about the correct order of moves in the top right corner can be found [ here. ] |
Dia. 67r.5: |
This is the final position in the top left corner in the variation with Young-Sun's endgame suggestion. Black has 16 points of territory and 1 prisoner, 17 points in total. White must get more additional points here than Black can keep in this area to compensate for the abovementioned loss of 18 points in the lower left. |
Dia. 67r.6: |
This White 68 (= H as White follow-up move after Black 67) was the move that looked the most straightforward to us. This move does not leave any threat in the centre for Black, so he must make two eyes for his group in the upper right. Update 2009: In the meantime we found, that playing F with 68 might be preferable for White. Update 2011: Amoung White's possible alternatives, B, C, and F seem to be strongest. Moves that now come into mind for White 72 are: A - "Standard" Osae of the Main Path. Seems to be too direct and too small. B - Yamada Shinji's Tsuke. C - Oki. May perhaps run into B with a change in the order of moves. D - Peep. Looks like the most interesting alternative for White. And seems to be the vital point in this position. E - Atari from the right. Seems to be too direct and too small. F - Atari from below. Will run into E with a change in the order of moves. We did not find any sequence for White that damages the Black corner as much as would be necessary to change the tables. Black will win the game. Surprisingly the strongest move for White seems to be that one on the right side, preventing the Black eye there immediately and then following the known Main Path (resulting in a 1-point win for Black respectively 2-points-win without the second Throw-in). |
Dia. 67r.7: |
Variation A: Black will keep about 15 points in the corner. White will get some additional points in the centre. The two Black stones in the left centre cannot be cut by White. Black gets about 10 points in this area and therefore will win the game. |
Dia. 67r.8: |
Variation B: Black will keep about 12 points in the corner. White will get about 7 additional points. The two Black stones in the left centre cannot be cut by White. Black gets about 5 points in this area and therefore will win the game. |
Dia. 67r.9: |
White cannot cut with 74. Black wins the Semeai in the corner. |
Dia. 67r.10: |
Pulling back with 73 is possible for Black, too, and might be the safer variation. Black will keep about 12 points in the corner. White will get about 7 additional points. The two Black stones in the left centre cannot be cut by White. Black gets about 5 points in this area and therefore will win the game. |
Dia. 67r.11: |
Variation C: If Black plays at 73 and let White connect to the outside (White 74 at 75 is not possible), it will result a change in the order of moves with the diagram before. The two Black stones in the left centre cannot be cut by White. Black gets about 5 points in this area and therefore will win the game. |
Dia. 67r.12: |
Answering the Oki White 72 with 73 might a bit dangerous for Black. Black plays 77 from the lower side (and not at 78) to prevent weakening his two centre stones. Black will keep about 11 points in the corner. White will get about a few additional points. The two Black stones in the left centre cannot be cut by White. Black gets about 10 points in this area and therefore will win the game. |
Dia. 67r.13: |
Variation D: It seems to be best for Black to play a purely defensive move with 73. Black will keep about 9 points in the corner. Perhaps White will not play at 82 at once. White will get about a few additional points. The two Black stones in the left centre cannot be cut by White. Black gets more than about 5 points in this area and therefore will win the game. |
Dia. 67r.14: |
White has the option to play at 74 at the outside immediately. Black will keep about 9 points in the corner. White will get 8 points later by separating the two Black stones on the left (due to the connection with 80). But even this one remaining point in this area will Black enable to win the game. |
Dia. 67r.15: |
If White plays inside with 74, it might be dangerous for Black to shut White in with 78. The safety-first measure for Black is to give way with 75 here. Black will keep about 10 points in the corner. White will get 8 points later by separating the two Black stones on the left (due to the connection with 82). But some remaining points in this area will Black enable to win the game. |
Dia. 67r.16: |
Perhaps White will connect with 78. |
Dia. 67r.17: |
Black has 5 outside liberties left - and White cannot take two of them direct. So it cannot be said that the approach-move Ko around 97 is really a Ko for White. |
Dia. 67r.18: |
Connecting the second time on the outside with 75 looks to be extremely dangerous for Black at first sight. But it results a change in the order of moves to something we have already seen before. |
Dia. 67r.19: |
Black has three effective liberties against White's two, so there is no need to play at 101 immediately. |
Dia. 67r.20: |
Variation E: Black will keep about 16 points in the corner. White will get about additional 6 points in the centre. The two Black stones in the left centre cannot be cut by White. Black gets about 10 points in this area and therefore will win the game. |
Dia. 67r.21: |
Variation F: Black will keep about 16 points in the corner. White will get about additional 6 points in the centre. The two Black stones in the left centre cannot be cut by White. Black gets about 10 points in this area and therefore will win the game. Update 2009: This move at 72 opens much better continuations for White in the top left corner, if the area of the top right corner is not played out before. |