RTG Problem 4 / Attempts

Sub-page of RTGProblem4

BrianMarshall: Well, I guess I'll make an attempt.

White first to play.  

To me, W1 seems the best move at Black's vital point. Even so, it seems Black has the chance to live in ko.

Black gets ko, I  

After B8, doesn't this depend on the ko?

unkx80: Nice try! Unfortunately the correct result is not ko. =)

Another attempt resulting in ko:

Black gets ko, II  

White invades fiercely...

Black gets ko, II - moves 11-13  

But after White 13, Black can again live by winning the ko. White 11 at 12, while tempting (to me, at least), is worse. B2 at W1 gives Black unconditional life.

Now an example of one failed attempt by White.

White fails  

After B2, I think a and b are miai for life.

unkx80: This statement is somewhat inaccurate. W3 at b, B4 at a, and W5 at c makes a ko.

Brian: Ah, I see. Thank you for the correction.

White fails again  

Now Black can easily get two eyes and live.

unkx80: If W5 is played at B6, then Black dies. Also, what happens when B2 is played at B6?

Brian: Hmm. If W5 is at B6, then Black cannot split at W5, or he'll lose black+circle. But blocking reduces the eye to three in a row, which White can kill. OK, I see that now.

But when B2 is at B6,

A better result?  

White can just extend with W3, preventing an eye in the corner. Black needs an eye on the left, so B4. Ah! W5 kills, then, by threatening a white move at B6. B6 defends, but W7 prevents the eye.

Is this the correct answer this time?

unkx80: What if B4 is played at B6?

Brian: If B4 is played at B6, then W5 played at B4 prevents an eye on the left.

Bill: But then the result is seki.

Important plays  

The situation after W1.

In my mind, for Black to form an eye at z he needs to occupy one set of: a-b-c-d, a-b-c-e, a-b-d-e, or b-c-d-e.

Alternately, Black could attempt to form an eye at d. This would require points c-z-e.

Since, at best, Black requires three of six points, White can prevent this.

unkx80: I admit that this problem is not so easy, and this isn't the Beginner Exercises series. I shall drop one hint: the main line to the solution involves shortage of liberties. Good effort there!

Main line  

Dieter: I have a feeling this is coming pretty close. Just another minute ...

Shortage of liberties  

In a real game I would have gone for ko, I'm afraid. B8 cannot connect at W9. W9 takes away the second eye.

unkx80: Bingo. =)

Thanks for the hint, unkx80, I had been under the illusion that Black could connect at W9.

RTG Problem 4 / Attempts last edited by Unkx80 on October 24, 2003 - 18:52
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