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PGB241
Skip to PGB231. Black threatens to cut off a white group and white has to take defensive measures. White 1: White has to connect at 3, of course, but this intermediate atari gives additional points and is sente. Black 2: Black saves a stone keeping alive the threat to cut. White 3: White connects, otherwise the cut off group would die and the dead black group in the top corner would return to life. BillSpight: If Black cuts, White can win the semeai in the corner with a reply at 'a'. However, White loses 3 1/2 points in the corner and quite a bit in the center and top side, as well. The connection at W 3 is big. Black 4: The move prevents white from saving a marked stone. It is interesting to compare the value of this move with the value of white 5 in the game. The most interesting question of the position is who wins a ko at the top. B4 is a reverse sente worth 3 2/3 points. The top is bigger. --Bill It is a good place to note that most weak amateurs are afraid of ko. We see an example of quite a large ko here that both players try to avoid. But, naturally, one of them is able to win it. Thus one of the players is wrong.
Black 1 on the diagram threatens to capture 4 white stones at the top. White has to answer 2 and start a ko. This ko is fairly large. Playing at 'a' black could forse white to conenct at 1 in sente, but this will probably give him 1 point more than what happened in the game. But that would be a safe variation if black did want to fight it, becaue White could also force ko. White 5: White threatens to capture two black stones, taking some territory from black. At this point of the game white was behind, so, perhaps sagari at 6 with following ko was a better move. White avoids ko as black did on the last move.
Black 6: This move saves two black stones. But is this the largest move on the board? It is worth 3 points by miai counting. The right side is bigger, as is the bottom. --Bill White 7: White connects his stone and threatens to take two black stones. Thus this is a local sente. Yes, but play the right side and bottom first. --Bill Black 8: Captures white's stone and saves one of his. White 9: Having got sente at the top white defends his territory. Black 10. Black conencts preventing white from saving the marked stone. This is a copy of the living page "PGB241" at Sensei's Library. (C) the Authors, published under the OpenContent License V1.0. |