Life In 19x19

I have a few questions about an opening that I play often. See SGF belows. Thanks!

My slightly old GoGoD (2008) has 3 games with this opening. In two of them black plays at "a", in one at "b"

Click Here To Show Diagram Code

[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . X . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . b . . |
$$ | . . . . . . . . . . . . . . . . a . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

These are the immediate continuations:

Click Here To Show Diagram Code

[go]$$Bcm1 Tiong Kee Soon 3d ama - Mykhailo Halchenko 5d ama, B+R
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . X . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . 3 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 2 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 1 . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Click Here To Show Diagram Code

[go]$$Bcm1 Han Sang-kweon 5d ama - Im Chae-hyeon 5d ama, W+1.5
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . X . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . 2 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 1 . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . . . . 3 . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Click Here To Show Diagram Code

[go]$$Bcm1 Takahashi Takamori - Nie Weiping, B+R
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . X . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 3 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 1 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . 2 . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

I think the takeaway point is that black can be happy to have two enclosures here.

I often play similarly. I play 7 at R6, so white no longer has miai for a two space extension.

I wonder if you can play this:

Click Here To Show Diagram Code

[go]$$Bcm9
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . X . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . a . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . b . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . O . . . . . , . . . 1 . , 4 . . |
$$ | . . . . . . . . . . . . . . . X 2 . . |
$$ | . . . . . . . . . . . . . . 5 . 3 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

As white I feel obliged to play at the point one space above 'b' (though I may suddenly die of slowness). As black I view 'a' and 'b' as miai, but I don't know if 'b' is the shape point here.


Edit: I've changed my mind.

This is weird. When I look at the posted position, the stones do not land on the intersections. I have never had this problem before, and am using the same browser as usual (Chrome).

I'd say corner enclosure is the best move when White splits the side. White should have approached the corner in the first place. If Black had occupied Hoshi instead of Komoku then the split is more correct.

maproom wrote:This is weird. When I look at the posted position, the stones do not land on the intersections. I have never had this problem before, and am using the same browser as usual (Chrome).

Do you have the page magnified? Magnification can break Eidogo in my experience; try hitting "ctrl +" or "ctrl -".

maproom wrote:This is weird. When I look at the posted position, the stones do not land on the intersections. I have never had this problem before, and am using the same browser as usual (Chrome).

It's a problem with chrome and Eidogo.

If you ever find a solution, please distribute it in the forum.

The reason emeraldemon found so few examples (and 2 were weak amateurs) is the r10 wedge is not the normal wedge with the 3-4 in the lower right: normal is r9. I'm not 100% sure of sequences to show why r9 is better but it can be understood qualitatively by looking at the gap on the side and picking the middle: this is r9.5. So which side to go to, r9 or r10? The shimari is stronger than the 3-4 (and we have nice approaches against the 3-4) so it makes sense to play away from strength and round down to r9.

As for sequences (sorry no diagrams from phone) I think with r10 if black plays checking extension at r12 and white makes a safe 2-space extension to r7 then black is quite content to make r5 shimari for profit and pressuring w's group. If the same idea happens shifted one line lower starting at white r9 then black only makes r4 kosumi shimari which is cramped. White may also approach the 3-4 (low or high but I prefer low) if checked from above. With r10 the gap between the wedge stone and approach is 4 spaces which makes a black pincer splitting these stones harder to deal with than were it 3 spaces with r9.

In Loons' diagram with the high approach I don't really like his O4. That's an old joseki that is slack territorially. Perhaps an argument could be made that it's a bit tricky for white to find an efficient continuation with r10 (though q8 looks ok to me)  and tenuki does seem a bit dangerous. I prefer r5 for points (and the usual hane, pull-back, solid connect, one-space jump) though a downside is it's likely gote and white gets to make a shimari at the top left if she choose not to defend at p10, but then we can invade at r8 (and in fact this board position is the same as if white approached first and that joseki played out, then black played checking extension at r10 which is a perfectly reasonable move, though given white has a 3-4 in the top right perhaps you would rather have approached there).

The other choice after the wedge is to play a move from below. Small shimari is most secure for the corner but puts less pressure on the wedge stone as it still has room for a 2-space extension to r7. I think most sensible for white is to then extend to r13, though tenuki could be considered. Big shimari means white has less room on the right but conversely black's corner is less secure. Black could even consider a checking extension at r8, white extends to r13, then black q5.

I'd probably play one of the shimaris as it simply gives black a nice position, but I disagree with SoDesuNe that white should have approached the corner in the first place rather than wedging. It's certainly more common in this position and allowing black to make 2 shimaris used to be considered bad, but with the big komi nowadays the wedge (at r9 not r10) is considered playable for white by at least some pros. If the 3-4 was at 4-4 then wedging at r10 is the usual place to wedge as it's in the middle of the gap, but in fact in the last few years has fallen out of favour (at least with 2 white hoshis, due to black f3, c6 r7/r8 r13 k4 giving black a dynamic position) and the approach against the hoshi at r6 is the popular move now (it used not to be played as after black plays one space low pincer taking the corner seemed to give black a nice right side, but that judgement was re-evaluated based on white having an excellent shoulder-hit reduction at q9 for later, which is why the one space low pincer has been replaced by the two space low pincer in the orthodox opening, as now if white takes the corner the later shoulder hit reduction gives black an extra line of territory, hence the development of various new double approach joseki for the two space pincer: isn't the evolution of fuseki/joseki theory wonderful!).

Uberdude wrote:I'd probably play one of the shimaris as it simply gives black a nice position, but I disagree with SoDesuNe that white should have approached the corner in the first place rather than wedging. It's certainly more common in this position and allowing black to make 2 shimaris used to be considered bad, but with the big komi nowadays the wedge (at r9 not r10) is considered playable for white by at least some pros.

My Fuseki knowledge is certainly not top-notch, since I "study" mostly classic games (Go Seigen being the only "modern" player), so I would like it very much if you can elaborate on this when you have the time. My feeling is that White's wedge makes it too easy for Black, even if it's closer to the 3-4 (and yes, as I read your post, I remembered this move, too ^^), I'm sure it is "considered playable for white by at least some pros" but then again, a lot of pros play a lot of funky stuff I never would (mostly because I can't follow).

So long story short: Is it just the 6.5 points Komi, which make it reasonable to grant Black two corner enclosures, or does White have plans/possibilities which lessens the value of two corner enclosures. (In this spirit: I really liked your explanation why White nowadays approaches the Hoshi in the Orthodox Fuseki instead of the split.)

SoDesuNe wrote:So long story short: Is it just the 6.5 points Komi, which make it reasonable to grant Black two corner enclosures, or does White have plans/possibilities which lessens the value of two corner enclosures.

I'm not aware of any particular continuations that work well for white, I think it's just that 6.5 is quite a lot of komi so she can afford to leisurely break up the board.

Focusing on just the right side:

Click Here To Show Diagram Code

[go]$$Bcm1 Top moves
$$----------------------
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . X . . . . |
$$ . , . . . . . , X . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . , . . . . . , f . . |
$$ . . . . . . . . d . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . e c . . |
$$ . . . . . . . a b . . |
$$ . , . . . . . , . . . |
$$ . . . . . . . X . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$----------------------[/go]

a = 1424
b = 476
c = 217
d = 54
e = 30
f = 13

If white plays the edge at d, the small enclosure is by far the most common response, 45/54 games:

Click Here To Show Diagram Code

[go]$$Wcm1 Other wedge
$$----------------------
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . X . . . . |
$$ . , . . . . . , X . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . 3 . . |
$$ . . . . . . . . . . . |
$$ . , . . . . . , . . . |
$$ . . . . . . . . 1 . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . 2 . . |
$$ . , . . . . . , . . . |
$$ . a . . . . . X . . . |
$$ . . . . . . . . . . . |
$$ . . . . . . . . . . . |
$$----------------------[/go]

After this exchange black usually tennukis to the other side, although the extension at "a" is also possible.

Overall, white plays some kind of approach to the bottom in 95% of the games I have with this position. the R9 wedge is more common than R10, but still pretty rare. Like I said, my GoGoD is from 2008 (need to update!) so if the trend Uberdude is talking about is newer than that it won't show up here.