topazg wrote:
Indeed, but where and how?
$$Bcm17
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[go]$$Bcm17
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This black 19 is already showing the effect of the white influence. When someone approaches a 4-4 and you already have the 4-10 in place, it is de rigeur to kick to make heavy, prevent slide to corner, and cause overconcentration due to the 4-10 stone in the way of a good extension. That you didn't play this presumably reflects your feeling that in this position although in one respect it makes f17 heavy, it also weakens and reduces connectedness to the k16 stone. (Maybe 24 could be one to the right).
$$Bcm17 Make white heavy or stronger?
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[go]$$Bcm17 Make white heavy or stronger?
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In fact I think the above is better for black than one point jump to 19 as that allows white to slide to corner (and of course if black doesn't 3-3 white is content to play there). This way white's group has more eyespace so is practically alive locally, black is simply running on dame and weak, and white can aim at
a.
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[go]$$Bcm17 Plus slide
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Another idea would be to simply invade at h17/h16/g16 directly, maybe as below?
$$Bcm17 Jumpy jumpy
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[go]$$Bcm17 Jumpy jumpy
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Then again, maybe you don't play on the top yet at all and just get on with playing some fuseki. Leave black to worry about k16 getting attacked later. If he plays submissive moves out of fear for an impending attack your thickness is working without you even trying. Once you have got some stones on the left side it is likely to make the invasion on the top even more powerful.
A rather similar position came up in a game I played with Matthew Macfadyen. He invaded in the wrong place (h17 on this board), so it's not an easy question if our 6d 25-time British Champion can get it wrong

. h17 was wrong because the cap at h15 was a good answer that helped d16 and k16 link together. That's why a 4th line invasion is better, it directly severs that connection.
A similar shape also came up in the recent Meijin title match.
http://gogameguru.com/yamashita-keigo-wins-36th-meijin/. In that game Iyama made a rather strange choice to build a gote wall which Yamashita then reduced with k16 (not holding back at f17/g17), but then black's wall in that game is not as thick as white's in topazg's example so k16 seems more reasonable. Iyama invaded at h17, the mistake move in my game, but in his game white does not have the ladder which is required to play the f15 cover after black f16 (see my Macfadyen game for the ladder variation), so white is forced to play the not-so-nice g16. (And in topaz's game white has the ladder to black can't f15 so h17 is back on the menu). In the comments on that game David Ormerod said he expected a black invasion on the 4th line. Maybe the lack of the ladder is why he did it, I would be interested to see a pro commentary!