Not many options here. White is not strong enough in this area to try anything.

Black could also have invaded at F17, but this is OK, too, I think.

Click Here To Show Diagram Code

[go]$$Bcm21
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . b . . . . . . . . . . . . |
$$ | . . . O . . . . 0 . O . X . . . . . . |
$$ | . . . , . . 1 . . a . . . c . X X . . |
$$ | . . . . . . . . X . O . . . . . . . . |
$$ | . . O . . . . . . . . . X . . . O . . |
$$ | . . . . . . . . . . . . . . O . . O . |
$$ | . . . . . . . . . . . . . . . O O . . |
$$ | . . . . . . . . . . . . . . . X X O . |
$$ | . . X , X . . . . , . . . . . X . X . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . O . . . |
$$ | . . . . X . . . . O . . O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

This was a little difficult to decide on. I am not sure if it could be called a forcing move, but it helps strengthen Black and puts a little pressure on White. I think White may be aiming at C, but for now the immediate concern is Black's stone at J15. Helps strengthen J15, and perhaps we can call A and B miai now. If White defends at A, Black will descend and destroy White's top-side territory and influence. If White defends at B, Black can play A and split White apart, staring a fight and gaining influence.
I think it is almost time to do something about White's top-left corner, and G16 may be helpful there.

Edit - fixed the diagram, which looked funny as I accidently made the letters upper-case.

No particular deep analysis on this one. It's just a shape point... I think...

On :
My initial post had been eaten, and I hadn't had a chance to explain it at all. Basically, I'd seen some examples of reductions of box formations, particularly in Keshi and Uchikomi. The book doesn't cover this exact white formation, but it presents lots of ideas. The book was too difficult for me that last time I tried to read it, but this kind of move stuck out at me, so I decided to give it a try here. I usually don't see fully formed box-moyos in my games, so it seemed like a good opportunity.

I expected , but I'm skeptical of . I don't see an obvious refutation, but it feels a little off. This is a shape point, which should either make black heavy or leave a nasty cut, then white can take time to deal with his own stones.

The scale swings back a bit now. Black's move was a bit cocky, and White goes on the attack.

One thing I have forgotten to comment on is that is misplaced:

Click Here To Show Diagram Code

[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . O . O . X . . . . . . |
$$ | . . . , . . X . . , . . . . . X X . . |
$$ | . . . . . . . . X . O . . . . . . . . |
$$ | . . O . . . O . . . . . X . . . O . . |
$$ | . . . . . . . . . . . . . . O . . O . |
$$ | . . . . . . . . . . . . . W . C O . . |
$$ | . . . . . . . . . . . . . . . X X O . |
$$ | . . X , X . . . . , . . . . . X . X . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . O . . . |
$$ | . . . . X . . . . O . . O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Now, after , Black should reject 'a' to 'd' in the following diagram:

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[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . O . O . X . . . . . . |
$$ | . . . , . . X d b , . . . . . X X . . |
$$ | . . . . . . a c X . O . . . . . . . . |
$$ | . . O . . e O . . . . . X . . . O . . |
$$ | . . . . . . . . . . . . . . O . . O . |[/go]

The reason is that they would just create a worm or a brick---an eyeless, heavy group.

'e' has White simply playing hane on the outside, and Black still has to struggle.

I believe that Black should try to stir up the corner now, trusting that something workable will develop. I really would like to keep things more straightforward for my co-players, but I do not see a better move after the last two.

This was also tough, I was not exactly expecting these last two moves. I think protects the corner and prevents Black from splitting off White's C14 stone. If Black crosscuts, White should be able to either keep the corner or attack Black's outside stones (C14 will help with this). White's three stones in the top-middle have almost been cut off, Black may go after those stones next. White may sacrifice one or two of them to link up with either the corner or the group on the right.

The idea here is to just continue to lean on white's corner. If this goes well, black may get strong enough to attack the group of three right stones at the top.

I also considered the cross-cut, but then I think white could force black to live small in the corner and get strong enough to really kick butt on the outside.

Nothing much to say here. Everything else just helps Black.

Click Here To Show Diagram Code

[go]$$Bcm31 B:1, W:0
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O O X . . . O a O . X . . . . . . |
$$ | . . O X . . X . . 7 b . . . . X X . . |
$$ | . . . . . . . . X . O . . . . . . . . |
$$ | . . O . . . O . . . . . X . . . O . . |
$$ | . . . . . . . . . . . . . . O . . O . |
$$ | . . . . . . . . . . . . . . . O O . . |
$$ | . . . . . . . . . . . . . . . X X O . |
$$ | . . X , X . . . . , . . . . . X . X . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . O . . . |
$$ | . . . . X . . . . O . . O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

For this move, Black is threatening to cut White at A or B. I think defending the cut at E16 would be too slow, and if White plays E18 Black can defend at G17 or G18. Now Black can start attacking White's three stones, and perhaps take some more territory on the bottom side. If things start to go bad, Black can still jump out around J13.

Edit: Fixed hidden diagram, I put "0" instead of "O" and accidently added some uppercase letters.

It's not a good idea for black to try to go pushing through here right now.

Click Here To Show Diagram Code

[go]$$B
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O O X . . . O W O 3 B . . . . . . |
$$ | . . O X . . X a 4 X 1 2 . . . X X . . |
$$ | . . . . . . . 6 X 5 O . . . . . . . . |
$$ | . . O . . . O . . b . . B . . . O . . |
$$ | . . . . . . . . . . . . . . O . . O . |
$$ | . . . . . . . . . . . . . . . O O . . |[/go]

If black tries to cut like this, it's all kinds of trouble. If he cuts at a, white can capture at b, and if he escapes with those four stones, white can connect at a and the rest of the group is probably gonna die. Not to mention the thinness of that two space jump... This is just one way for this to go badly for black.

Click Here To Show Diagram Code

[go]$$B
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O O X . . . O W O 3 B . . . . . . |
$$ | . . O X . . X . . X 1 2 . . . X X . . |
$$ | . . . . . . . 4 X . O . . . . . . . . |
$$ | . . O . . . O . . . . . B . . . O . . |
$$ | . . . . . . . . . . . . . . O . . O . |
$$ | . . . . . . . . . . . . . . . O O . . |[/go]

This might be better for white.

Of course, if black doesn't push and cut, then becomes somewhat meaningless. So I imagine Harleqin is going to try to find some other way to make use of that stone.

Well, that last exchange was likely aji keshi; for example, attaching at H17 has lost its force, and there is no chance to peep from the second line instead later. Black cannot push through as long as White can cut in sente at H15.

Now, things have developed in such a way that the move I initially rejected as bad shape can actually be good, since it threatens to either push through on the right or isolate the lone white central stone. The alternative, attaching to the left of that central stone, seems to strengthen it too much.

Zengo is surely quite an experience...

Click Here To Show Diagram Code

[go]$$Bcm31 B:1, W:0
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . 0 . . . . . . . . . . . . |
$$ | . . O O X . . . O O O . X . . . . . . |
$$ | . . O X . . X . . X . . . a . X X . . |
$$ | . . . . . . . 9 X . O . . . . . . . . |
$$ | . . O . . . O . . . . . X . . . O . . |
$$ | . . . . . . . . . . . . . . O . . O . |
$$ | . . . . . . . . . . . . . . . O O . . |
$$ | . . . . . . . . . . . . . . . X X O . |
$$ | . . X , X . . . . , . . . . . X . X . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . O . . . |
$$ | . . . . X . . . . O . . O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

I was not expecting , but I can see why it is a good move. This is very tough for White... I feel that threatens to link up at E18 (and makes some eye space). If Black blocks there next, White can connect at L16 and try attacking Black's corner group (perhaps there is a weakness around a) or running out. Black's group is still floating too, but I think this may be an easier fight for Black, especially as Black has stones at E10, and White's G10 stone looks a little lonely.

Now that black is connected, this cut works. I'm surprised white passively slid underneath like that. I think it would be better to connect out and avoid getting sealed in, rather than trying to live locally. Accordingly, I think cutting, thereby sealing white in, is very big. does take away some of black's potential eye-shape, but there is so much running space that there isn't an effective attack.

I was actually quite tempted to tenuki. R3 is pretty huge, and H3 is big.

White is in a difficult position now. This reduction ended up being pretty effective, and white seems to be behind. If black gets R3, I'm not sure where white's going to get enough territory from. At the same time, a reduction of black's lower left is also urgent.

I really thought White would connect at L16.

Click Here To Show Diagram Code

[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O O X . . . O O O . X . . . . . . |
$$ | . . O X . . X . . X 1 . . . . X X . . |
$$ | . . . . . . . X X . O . . . . . . . . |
$$ | . . O . . . O . . . . . X . . . O . . |
$$ | . . . . . . . . . . . . . . O . . O . |
$$ | . . . . . . . . . . . . . . . O O . . |
$$ | . . . . . . . . . . . . . . . X X O . |
$$ | . . X , X . . . . , . . . . . X . X . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . O . . . |
$$ | . . . . X . . . . O . . O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

That would have kept Black completely separated, the white group would have had miai of the slide and the centre, and the black niken tobi would have got thin. Now, White almost has to connect at E18.

Cutting now seems mandatory:

Click Here To Show Diagram Code

[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . O O X . . . O O O 2 X . . . . . . |
$$ | . . O X . . X . . X X 1 . . . X X . . |
$$ | . . . . . . . X X . O 3 . 4 . . . . . |
$$ | . . O . . . O . . . . . X . . . O . . |
$$ | . . . . . . . . 6 . 5 . . . O . . O . |
$$ | . . . . . . . . . . . . . . . O O . . |
$$ | . . . . . . . . 8 . 7 . . . . X X O . |
$$ | . . X , X . . . . , . . . . . X . X . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . O . . . |
$$ | . . . . X . . . . O . . O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

However, White cannot really do anything with this, and and rather help Black's own moyo while White is running on neutral points. Therefore, I think that it is best to leave the aji open for now and contest the black moyo in the lower left---if Black gets there first, the game is really over.

I was not expecting , but I see now that the "fight" on the top can be resumed later, White playing around there may just end up helping Black.

In the lower-left corner, I do not know this joseki (if it is a joseki at all, that is). The side looks bigger than the corner, so I will defend there. I am not sure if White can live in the corner, and White can't crosscut right now (else Black will play B3). Even if White manages to live, Black should be happy to take the side, and perhaps attack White's center stones around G14 next.

Harleqin played a standard probe; I presume he's trying to borrow some strength from black's shimari to begin a reduction of the box formation. After black blocks on the outside like this, the only local response is to cross-cut. The idea is to sacrifice the probe stone to get a light group established inside black's moyo.

It's probably also possible to tenuki at this point, treating as a forcing move and coming back to use its aji later, but reducing this area is most urgent right now, so I might as well continue locally.

Click Here To Show Diagram Code

[go]$$B
$$ | . . . . . .
$$ | . . X , X .
$$ | . . . . . .
$$ | . . . . . .
$$ | . . b . 6 .
$$ | . 4 . a . .
$$ | . X W . c .
$$ | 5 O X 2 . .
$$ | . 1 3 . X .
$$ | . . . . . .
$$ | . . . . . .
$$ ------------[/go]

This is one possible sequence that kyu players commonly learn, but I don't think it's the most common among pros. It is played at the pro level though.

The exact placement of varies, but the idea is to stay light. Playing a would leave peeps at b and c and make the whole group heavy. With something like , white can easily sacrifice the original stones to make a stronger shape.

Click Here To Show Diagram Code

[go]$$B
$$ | . . . . . .
$$ | . . X , X .
$$ | . . . . . .
$$ | . . . . . .
$$ | . . . . . .
$$ | . b . . . .
$$ | . X W a . .
$$ | . O X . . .
$$ | . . . . X .
$$ | . . . . . .
$$ | . . . . . .
$$ ------------[/go]

I think a and b are actually more common, but I am less familiar with them, and I think they get pretty complicated. Some of the variations after b depend on a ladder which, remarkably, because of the the white stone at L15, seems to favor white at the moment. I'm going to reread it several more times because it's a tricky ladder, complicated by the many black stones near L15 and the black stone at E10.

Black could also play like this:

Click Here To Show Diagram Code

[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . O O X . . . O O O . X . . . . . . |
$$ | . . O X . . X . . X X . . . . X X . . |
$$ | . . . . . . . X X . O . . . . . . . . |
$$ | . . O . . . O . . . . . X . . . O . . |
$$ | . . . . . . . . . . . . . . O . . O . |
$$ | . . . . . . . . . . . . . . . O O . . |
$$ | . . . . . . . . . . . . . . . X X O . |
$$ | . . X , X . . . . , . . . . . X . X . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . a . . . . . . . . . . . . . . . . |
$$ | . 3 2 . . . . . . . . . . . . . X . . |
$$ | . X O 1 . . . . . . . . . . . . . . . |
$$ | . O X b . . . . . , . . . . . O . . . |
$$ | . . . . X . . . . O . . O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

with continuations 'a' or 'b' possible. However, this makes the game complicated, and I feel that Black is comfortably ahead. So, I expect something like this to transpire:

Click Here To Show Diagram Code

[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . O O X . . . O O O . X . . . . . . |
$$ | . . O X . . X . . X X . . . . X X . . |
$$ | . . . . . . . X X . O . . . . . . . . |
$$ | . . O . 7 . O . . . . . X . . . O . . |
$$ | . . . . . . . . . . . . . . O . . O . |
$$ | . . . . . . . . . . . . . . . O O . . |
$$ | . . . . . . . . . . . . . . . X X O . |
$$ | . . X , X . . . . , . . . . . X . X . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . 6 . . . . . . . . . . . . . . |
$$ | . 4 . . . . . . . . . . . . . . X . . |
$$ | . X O . . . . . . . . . . . . . . . . |
$$ | 5 O X 2 . . . . . , . . . . . O . . . |
$$ | . 1 3 . X . . . . O . . O . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

I am not quite sure about the best move for , but it should be somewhere around there.

I missed this when I played my last move as Black, but it looks like White can play lightly and escape, perhaps reducing/destroying Black's territory on the left side. Next I expect Black to defend at C3 or capture at A4, and then White can try something like F5 to get out. Maybe first White could peep at D9 as a kind of forcing move, but White should probably build up a little strength before going after those Black stones (C10 and F10).