How to respond to a Cap?

Xai · #1

Hi,

I am looking for general advice on how to respond to the "Cap" move, such as the one in this diagram. I did not find the pages at Senseis very helpful because the pages I found don't have a response by the player doing the "capping", for a lack of a better verb. I wasn't sure of a good way to respond to :b3:

Here's the diagram lifted from a game I just played

Click Here To Show Diagram Code: [go]$$Bc 19x19 board $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . 1 . . . . . . . . . | $$ | . . . O . . . 2 . , . 3 . . . O . . . | $$ | . . . . . . . . . O . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

illluck · #2

In this case, I would consider cutting as below. Whether it's correct probably depends on a lot of factors, but just considering the stones right now I think it's hard for black. "a" might be ok to attack on a larger scale, but I suspect white is not solid enough in area?

Click Here To Show Diagram Code: [go]$$Bc 19x19 board $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . a . . . . . . . | $$ | . . . . . . . . . 1 4 . . . . . . . . | $$ | . . . O . . . 2 . , . 3 . . . O . . . | $$ | . . . . . . . . . O . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Kirby · #3

I like 'a' better.

Bill Spight · #4

Here is my first thought.

Click Here To Show Diagram Code: [go]$$Bc 19x19 board $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . 1 . . . . . . . . . | $$ | . . . O . . . 2 . , . 3 . . . O . . . | $$ | . . . . . . . . . O . . . . . 4 . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

And in this kind of situation, my first thought for :w2:

.

Click Here To Show Diagram Code: [go]$$Bc 19x19 board $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . 1 . . . . . . . . . | $$ | . . . O . . . . . 2 . . . . . O . . . | $$ | . . . . . . . . . O . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Joaz Banbeck · #5

As I understand it, the essence or meaning of a cap is to prevent the opponent from expanding in a particular direction. In this instance, he is trying to prevent you from expanding northward. Given that, once you have gotten around him with :w2:

...

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . 4 . . . . . . . . . . . | $$ | . . . . . . . . . 1 . . . . . . . . . | $$ | . . . O . . . 2 . , . 3 . . . O . . . | $$ | . . . . . . . . . O . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

...the proper direction should be :w4:

.

sekoj · #6

After black 3 I would j6 without thinking >.> Have to agree with Bill's 2 though

Uberdude · #7

I have to disagree with Bill's bump. Whilst it can enable you to defend the territory on both sides (but not the corners), it is a vulgar bad-style move that unnecessarily strengthens your opponent and one I have learnt to eliminate from my intuition.

To the original question, the knight's move to one side is the standard answer. Which side is better obviously depends on the rest of the board. A common strategy for black in the 2 4-4s and 3-10 shape (I'm ignoring q7 and d9 for now) is to cap, and then if white answers with a knight's move to one side you invade the 3-3 on the side he answered. The thinking here is "Which side do you want points?", "Oh that one, ok I'll take them away at 3-3". If white then plays out a standard 3-3 invasion joseki the cap for knight's move ends up as an excellent exchange for black as white is overconcentrated. Imagine black played 3-3 first and then capped, white would of course not defend to the left as he is already very strong there.

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 8 . . . . . . . . . . . . . . . . | $$ | . 7 6 . . . . . . . . . . . . . . . . | $$ | . 5 4 . . . . . . B . . . . . . . . . | $$ | . . 3 O . . . W . , . . . . . O . . . | $$ | . . 1 2 . b . . . O . . . . . . . . . | $$ | . . a 9 0 . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Xai, you say black's 3 was the move that you didn't know how to answer? What did you expect? If l3 that is good as it's the normal move. When faced with an unexpected move the thought process I suggest is: "What did I expect, and how is his move different?". Another very good idea with unexpected moves is to consider tenuki. A good move elsewhere is unlikely to be that bad (unless the local situation is urgent) So here l3 would have taken a liberty from your k3 stone so you want to answer. But m4 didn't take a liberty so it is much easier for you to ignore.

Cutting at m5 is a plausible suggestion. The shape peep at m6 feels like an overplay to me. But the points that really scream out to me in this position are the 3-3 points: as black my aim would be to live in the corners, quite possibly in sente (obviously white can try some other variation to make it gote) and then so long as the cap doesn't die white has not much territory. So I want to play here (or maybe c4):

Click Here To Show Diagram Code: [go]$$Bc Corners are key! $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . 1 . . . . . . . . . | $$ | . . . O . . . 2 . , . 3 . . . O . . . | $$ | . . . 4 . . . . . O . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The reason I think this corner is more important than the right one is should black invade at c3 the h4 stones ends up overconcentrated. If black then invades the other 3-3 it makes white thick which makes an attack on the capping stones much more powerful (EDIT: but actually if black can 3-3 in sente and then help the centre group maybe white is a bit sad, so I think Bill's q3 suggestion is good too, even though c3 then makes me sad - white can't have everything). And if black attaches at q3 white could play like below and laugh all the way to the bank. White could also consider hane on the outside (r3 at p3) to separate the capping stones and let black live in the corner and then attack the capping stones, but I am unsure of the profit that way. This way is obvious profit.

Click Here To Show Diagram Code: [go]$$Bc $$$$$$$$$ $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . X 9 . . . . 6 . . . | $$ | . . . O . . . O . 8 . X . . 5 O . . . | $$ | . . . O . . . . . O 7 . . . 3 1 2 . . | $$ | . . . . . . . . . . . . . . . . 4 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Here is a nice pro example of ignoring the cap. As white has an extra knight's move on both corners he tenukis to another good point, and is ready to fight when black follows up on his cap with an attachment.
http://gogameguru.com/commentary-kim-ji ... -card-cup/

mitsun · #8

Almost all of the suggested responses have merit, and could be good depending on the surrounding position. Here is how I would interpret them:

L5 cut is the most severe response, leading to the most difficult continuations. This is the first move to consider, assuming the ladder does not work for B, and especially if W is stronger in the local area. W should have prospects of making territory by attacking, likely by killing one side or the other. B has to consider this response before playing the knight move, and believe he can survive the fight.

Jump to H6 or press at J6 are excellent moves, appropriate if W can make a moyo in the lower left quadrant, using the D9 stone efficiently. Both moves will allow B to strengthen his position to the right, so W declines to attack strongly, and does not count on much territory in the lower right.

M6 looks like a "thank you" move to me, forcing B to protect the knight's move weakness. W would have to be exceptionally strong in this area, with prospects to kill everything, for this to be a good move.

Q3 corner is undeniably large, and it does make it a bit more difficult for B to get a base, but it seems a bit weak to me, not quite sure why, maybe just a bit slow and lacking severity. Still, it could be quite playable in some circumstances, say if W does not think he can gain much by an immediate direct attack, and there are not good moyo prospects on the other side.

D3 corner ( or C3 or C4 or C5 depending on surroundings) looks better to me than Q3 corner, for the reasons Uberdude gives. W might want to play this way if he dislikes the result when he plays one of the moyo moves (H6 or J6) and B immediately invades at C3 to take the corner territory.

K4 bump (for move 2, instead of knight move) says W wants as much territory as possible along the bottom, but has no interest in a moyo on either side (since B gets to choose which side), and has no desire to attack the capping stone. B will presumably like this response, since the original cap more or less offered to give W bottom territory in order to erase center thickness and moyo prospects. This could be the best strategy for W, if he can count that he gets enough territory for a win, or it could be the worst strategy, if it allows B to make enough reduction in W territory to win. Most of the time I think it is probably better for W to decide which side is more important, then make a knight move in that direction, as in this game. If the position is completely symmetric, this move could be appealing.

Xai · #9

Thank you all very much for the replies. All of you showed me some good ideas that I will be able to learn from and apply to my game. During the time pressure of the game I responded poorly. As I suspected, the move that I made for :w4:

was not mentioned at all, which is the reason that I posted the question!

tapir · **#10**

Xai wrote:

Hi,

I am looking for general advice on how to respond to the "Cap" move, such as the one in this diagram. I did not find the pages at Senseis very helpful because the pages I found don't have a response by the player doing the "capping", for a lack of a better verb.

Me neither. Reductions, probes... are all a little underrepresented at SL and in amateur play in general (maybe I am generalizing my own playing style here). However, it feels quite strange that: When people look for something at SL and don't find it, they naturally look elsewhere, but rarely do they bother to come back and add what they learned. As a player who learned most from obsessively reading SL, I found the book by Fujisawa Hideyuki on reductions very useful (as it has many surprising and new moves to me, still reading) as it covers many blind spots.

How to respond to a Cap?

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