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OGG2 - White Connects with 152
   

DaveSigaty: I thought this was a very interesting point in the game. When W played elsewhere in the actual game we moved immediately to the large yose stage. Connecting at 152 below instead leaves the situation on the right still unsettled. What happens here?


Variation 1

[Diagram]
Diag.: OG2 (151 - 160) variation 1

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

What happens next?


[Diagram]
Diag.: OG2 (151 - 160) variation 1

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

Dieter: I think - without calculating much - that Black 'a' makes miai of capturing W4 and making an eye at 'b'.


[Diagram]
Diag.: 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 B. See JamesA's alternatives further down the page. The marked B stone would be better off at 'a', reducing the W stone's liberties.

[Diagram]
Diag.: Ko

Bill Spight: Good point, unkx80! But maybe White should make ko. (Black can live by playing B 2 at 7 in the previous diagram.


[Diagram]
Diag.: Black lives?

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


[Diagram]
Diag.: White kills?

Bill: Thanks. I overlooked B 8. But W 5 above looks like a mistake. Better the sagari, threatening to connect either way.


[Diagram]
Diag.: White kills? Var. 1

If B 1, W 2 connects. B 3 is met with W 4, containing Black.
Instead of B 1, if B a, W b.


[Diagram]
Diag.: White kills? Var. 2

W 2 secures the corner, I believe. Because of Black's damezumari, the oiotoshi of B 5 does not work.

unkx80: Thank you, Bill! =)



[Diagram]
Diag.: OG2 variation 1a

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



Variation 2...

[Diagram]
Diag.: OG2 (151 - 160) variation 2


What else might Black choose after White connects?


JamesA: How about this for an alternative black play?

[Diagram]
Diag.: OG2 alternative for black? var 1

DaveSigaty: This 1 looks like nice timing. W answers with 2 and 4 to prevent an eye and cut B off from the center. I had not looked at 5 (only 'a') in deciding to play the marked stone. This is better as it reduces the W stone's liberties. At this point B is alive as far as I can see.


Remaining Aji 1

[Diagram]
Diag.: OG2 alternative for black? aji 1

Varous aji remains however. The most serious is W's descent at 1 here. If B does not answer (for example he protects the lower right instead, W kills the B group by forcing a connection to the marked stone. W would like to test B along the lower right side to see whether the aji is of use. B has to be careful in answering on the lower right so as not to give W an opportunity to use 1 to her advantage.

Remaining Aji 2

[Diagram]
Diag.: OG2 alternative for black? aji 2

If the play on the lower right side proceeds in a way that W does not use the descent to the edge in the previous diagram, W may choose to capture the ko in sente. B can not afford to let W cut at 'a' and must answer with 2 or some other move. This can be important later because if B manages to cut the W stones in two at 'b', both the resulting W strings may have to take time to secure two eyes.


[Diagram]
Diag.: OG2 alternative for black? var 2

[Diagram]
Diag.: OG2 alternative for black? var 2(cont'd)

6 at 1


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


Sideline question

[Diagram]
Diag.: OG2 (151 - 160)

This is just a question: Not that white wants to, but doesn't the solid connection at W152 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 B151 may have been a bad move:


[Diagram]
Diag.: OG2 White connects underneath:

If Ba 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.


Dieter: You know what I think ? After having read the whole discussion and considering the truckloads of aji that exist along the right side, I think Nonny was correct all the way when he questioned my move at 135 (see OngoingGame2). I also think his proposal for improvement was correct. Black 135 should have been played at 4 in variation 1 (top of this page). Gentlemen, I take my hat off to Nonny.

HolIgor: Come on, Dieter. If playing 4 was necessary then, of two moves, 133 and 134 the latter was larger by far. I think that Dnerra, 4d, eased up a little bit on white to make the game closer.

dnerra: Oops, I think you should show a little more disrespect to my rank, HolIgor! :) (Which is 3d, not 4d btw.) So there were 3 moves of mine that got particularly criticized.

  • B121: I am still not convinced this one was bad.
  • B133: Here I have to agree completely. I hadn't realized that W134 would be sente. In the game, B133 turned out particularly bad, as W effectively got to play W154 in sente. It seems to me that B133 would best have been played here:

[Diagram]
Diag.: OG2 Best move at 133?


  • B151: 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 W had connected at B153 with 152, then Black might have lost more on the lower right than 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 ar 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. :-)



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