OGG2 - White Connects with 152

OG2 (151 - 160) variation 1  

White connects and Black takes the big point on the left, treating 1 as a forcing move. I think that White 4 is the natural play.

What happens next?

OG2 (151 - 160) variation 1  

HolIgor: When taking the big decision I considered this variation and thought that White forced Black to take too many points. And here Nonny's question comes.

Dieter: I think - without calculating much - that Black a makes miai of capturing White 4 and making an eye at b.

OG2 (151 - 160) variation 1  

unkx80: This is a 2 am post, and a continuation from the previous diagram. Did I read wrongly?

DaveSigaty: There is definitely bad aji left here for Black. See JamesA's alternatives further down the page. The stone would be better off at a, reducing the white stone's liberties.

Ko  

Bill Spight: Good point, unkx80! But maybe White should make ko. (Black can live by playing at in the previous diagram.)

Black lives?  

unkx80: (3 am) Hmm, thanks. I will look at this again some other time. I think I should go to sleep. =P

White kills?  

Bill: Thanks. I overlooked . But above looks like a mistake. Better the descent, threatening to connect either way.

White kills? Variation 1  

If , connects. is met with , containing Black.
Instead of , if Black a, White b.

White kills? Variation 2  

secures the corner, I believe. Because of Black's shortage of liberties, the oiotoshi of does not work.

unkx80: Thank you, Bill! =)

OG2 variation 1a  

Dave: Let's see! I think this is one of the main theoretical lines. The questions seems to be whether Black can find something that works after forcing moves to here. I think that a and b are miai for White to prevent both a second eye and a connection to the left.

OG2 (151 - 160) variation 2  

What else might Black choose after White connects?

OG2 alternative for Black? Variation 1  

DaveSigaty: This looks like nice timing. White answers with and to prevent an eye and cut Black off from the center. I had not looked at (only a) in deciding to play . This is better as it reduces the white stone's liberties. At this point Black is alive as far as I can see.

Remaining Aji 1

OG2 alternative for Black? Aji 1  

Varous bits of aji remain, however. The most serious is White's descent at here. If Black does not answer (for example he protects the lower right instead, White kills the black group by forcing a connection to the marked stone. White would like to test Black along the lower right side to see whether the aji is of any use. Black has to be careful in answering on the lower right so as not to give White an opportunity to use to her advantage.

Remaining Aji 2

OG2 alternative for Black? Aji 2  

If the play on the lower right side proceeds in such a way that White does not use the descent to the edge in the previous diagram, White may choose to capture the ko in sente. Black cannot afford to let White cut at a and must answer with , or some other move. This can be important later because if Black manages to cut the white stones in two at b, both the resulting white strings may have to take time to secure two eyes.

OG2 alternative for Black? Variation 2(cont'd)  

6 at 1

Black seems OK in these variations, but I'd bet money that I've missed something....

OG2 (151 - 160)  

This is just a question: Not that White wants to, but doesn't the solid connection at White 152 mean that White can put the marked stone in motion, threatening to connect directly or underneath? I'm probably missing something, but it seems to me that because of the potential atari by White at a, connection underneath is possible? Please let me know what I'm not considering. --Nonny

dnerra: It seems you are right; I did not see this, and it means that Black 151 may have been a bad move:

OG2 White connects underneath:  

If Black a next, White just connects at b and Black cannot cut. So Black would follow up with c, but this is gote and so White might as well get to play there.

Maybe White would play this sequence after capturing at d with sente.

OG2 Best move at 133?  

• Black 151: I now think that it is bad, but for a different reason: The exchange that happened in the game still seems good for Black to me. But if White had connected at Black 153 with 152, then Black might have lost more on the lower right than he gained in the upper right if we take Nonny's remarks into account.

But,to stress that point with the disrespect a little, I would say that I usually commit at least two blunders around this stage of every game that are worse than the mistakes listed here. If you don't believe me I will try to record them in one of my next tournaments and present them here on SL. :-)