This situation comes from a "teaching game" I played against a 3-dan. The way Black handled the ko made a big difference, and we can learn from his mistakes. In response to Black 85, White plays atari at 86. If you were Black, what would you play now? We will review this at the end. Diagram. Basic: In the game, Black started the ko directly with the atari at 87. Black 89 was the first threat played. What do you think of this threat? Day 1; Game I: (86-90) This article by Dai Junfu 8d was translated into Spanish by Isaac Ripoll 3d for La Esquina. Pushing with 1 is the right threat because it creates more threats with A and B. In other words, this move not only serves as a threat but also increases the total number of them. Diagram 2: The Right Threat In the game, Black captured the ko with 91, but White 92 is a good counterattack. Locally, Black has no good defense to save ☐; now we see the cost of Black 89 in Diagram 1: it was a threat that has now produced a big loss. Keep in mind that White 90 should not have been played at A, since Black could then reproduce the situation in Dia. 2 by pushing at B.Dia. 3; Game II: (91-95); White 94 = ▲ What do you think of Black's threat at 95? If winning the ko is urgent, White can play the kosumi at 1 before defending again with 3. This leaves a huge weakness in the center of Black's position, forcing Black to protect with 4; White could then eliminate the ko with A. However, in this position capturing the stone at A is not urgent, since it does not threaten Black's group and White's group in the corner is in no immediate danger. Dia. 4: White's trick If White were to finish the ko now, Black could reduce with B and even threaten an attack with the cut at C; this sequence is bad for White. In any case, White has revealed his plan too soon. Black 93 in Dia. 3 is a mistake; the best defense is to extend at 1. If White pushes with 2, Black can invade with 3 and 5, preserving the possibility of starting an attack with A, which would try to kill White with the corner ko. Also, White has no reason to play B and C to eliminate this ko unless Black starts with A, because that would let Black play twice elsewhere. Day 5: Black's Best Response If Black 93 in Dia. 3 blocks at 1, White 2 brutally separates Black's groups. After White 16 the corner group is already alive, and after the connection with White 18, both of Black's groups in the northeast and in the center are in danger. Dia. 6; Black is in danger Against Black's threat at 95 in Dia. 3, blocking with 96 is the correct response for White; now Black's invasion of the upper side will be less severe. In other words, Black has lost something with this threat. Faced with a ko that barely threatens the life of the corner group, White decided to ignore it and add a move in the center with 98, punishing the ko threat that Black had played in the center. Day 7; Game III: (95-104) Once Black ends the ko with 99, White 100 makes the group alive, so in the end White lost nothing in this ko. Black 101 misses the last chance. Black has once again wasted his sente; once White defends with 104, Black no longer has any chance of recovering this game. Looking at the final result, we can see that Black only won the ko without gaining anything else, while White was able to complete its moyo in the center and also defended the top side. Black has to reduce the center with 1. White has no reason to split the groups in the center with 2-6, because Black's group in the northeast is already alive. Day 8: Black's Last Chance Compared with Diagram 1, Black has no reason to start the ko with A; it is enough to strengthen the center with 1-7. With Black's influence in between, White's potential in the center neutralizes itself. Another option, instead of reinforcing the center, would be a direct reduction with B, since White's attack with C is not severe; Black only has to escape toward the center with D. Diagram 9: What Black should have played. In any case, Black's group can live with E, so White's attack would be in vain. Conclusions: Avoid starting a minor ko when there are still interesting areas left to fight over. Creating cutting points can generate more ko threats. Avoid playing ko threats that lose something when you are fighting a minor ko, because you risk losing more than the ko itself is worth. Published in La Esquina #011 (November 2026). Download the full magazine in PDF
