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keima slide and ogeima slide
Difficulty: Dan level
Keywords: Shape
Discussion originally on answer keima with kosumi.
This is another common kosumi response to a keima.
But when White plays ogeima, the tobi is the usual response. I learned this years ago. Frankly, I have forgotten why. Yesterday I saw Prof. Teigo Nakamura 6-dan. He has the most encyclopedic go knowledge of any amateur I know. He had forgotten why, too. ;-) But he spent a few minutes playing with the position and came up with the answer.
If Black answers the ogeima with kosumi (both marked), later he can play Black 1 - Black 7.
If White protects with White 1, she threatens to jump in at a. Note that Black had responded at a instead of the kosumi (marked), he would still threaten to play at b, but White would not have a big threat after White 1. (Moved from answer keima with kosumi.) Charles Matthews I have wondered about this, having seen something very similar in an old Japanese book on tesuji.[1] Firstly, there is no 'shape-based' rule.
If one looks at this sort of pattern, just somewhere on the side, then Black a and Black b are both commonly seen. If one specialises to the case of the small high enclosure, then the diagonal move answer is more popular:
Black 1 here is much more popular than Black at a.
Black 1 is more popular than Black a. These come from database search: they may contradict the book I read. Looking, as one should, into the game context, the diagonal move answers do seem to be in the type of position where Black wants to take sente.
There may be something in the idea that the one-point jump answer Black 1 here invites White 2 and 4, at which point Black would want to add another stone here.
In the keima slide case, White's immediate cut with 4 and 6 is possibly tactically. (White would like a good ladder for this, but perhaps that isn't a precondition?) [1] A 1955 book by Kano Yoshinori. Here are the actual positions.
Black 1 is given as correct. In three pro games, Black played tenuki from the corner.
Black 1 here is given as correct. This is more plausible: a low-ranked Korean pro has played a, but as a rule this is what one sees. This is a copy of the living page "keima slide and ogeima slide" at Sensei's Library. ![]() |