Xuanxuan Qijing Problem 20 / Attempts

Black to play.  

Post your solution here.

HolIgor: I won't post a solution yet. In fact I am amazed at the level of this problem. Could it be dan level? We have not heard from our dans yet.

I lost it in an IGS game. I agreed gladly to this position considering it a sure win for Black. But it proved to be much more difficult than expected. So, I decided that Black loses here.

- Perhaps I should have added I'm a European 2 dan. Goran

When I opened a book at a random diagram I could not believe my eyes. Is it possible for Black to win?

Some general words about the solution. The motifs are normal: a group with an eye wins agains a group without eyes, hence some eye stealing, a sacrifice to gain a tempo, shortage of liberties. But everything requires exact reading.

How about a ko? (9 at 1)  


HolIgor: Black can do better.

Black 1?  


I'm not sure of the best 'defence' for White, but I cannot see any quick way for White to save his stones after B1...?

Black 1 fails  

White rebuts this with a simple outside attack true to the fundamentals. HolIgor

Oops. I thought Black could cut one to the left of W6, but he cannot.

DaveSigaty: I couldn't figure this one out. Finally I gave up and searched my books for an analysis - I wasn't even close to finding the key play (which is Black's second play rather than his first!). The honor of posting the answer belongs to HolIgor when he is ready.

My attempt  

Before HolIgor does so, allow me to make a try... After B7, White clearly is one move behind.

Better defense (Black 11 at a, White 12 at b)  

A better defense for White seems to be W2 here. After White 12, Black loses despite the me ari me nashi.


Black however has an improvement with B7 here. First destroying the eye, then moving out seems to be enough to save Black.

No good either  

Playing W6 on this side does not work either. After B7, the best White can do is to capture B5 in sente.

Last defense?  

One more line of defense seems open for White, namely W4 here. But the B5 - W6 exchange again saves the day. If White plays Wh6 at a, Black plays at W6, and gains liberties again.

-- AndreEngels

White's defense?  

I hate disagreeing with stronger players, but how does Black play after W6 here? Black must defend against White a. Black at b gives White d and Black dies.

Black at a gives White c and Black dies. Black at e again gives White c and Black suffers? -- MortenPahle

You should not hate disagreeing with me. Certainly not when, as in this case, you are right and I am wrong. -- AndreEngels

HolIgor: The move proposed by Morten is a strong defence but Cho shows how to beat it. Consider it a new problem.

Black wins still!  
Black e, White c Black 3?  


Yes, Black sacrifices two stones but kills the rest. --HolIgor

Thus the first move is found:

Black 1 is the first move.  

White's strongest defence is W2. So the problem is to find Black's second move; which is the key, as Dave put it.

-- HolIgor

Black 1 seems to work  


Yes, this is the solution. The variations should be considered further:

JBS Solution?.

Alternative solution?  

dnerra: I just looked at this problem and read out this simple-minded sequence. It looks so obvious that it might be worth discussing: What did I miss in this sequence?


Apparently, W1 in this diagram is the only move here. (White a, Black b, White 1, Black c should usually be very good for Black, as White has to come back and make life at d.



The usual tesuji in such cases is this Wh1. I give only one variation. But one has to be very careful.

The problem is very good. It was published more than a half millenium ago.

Xuanxuan Qijing Problem 20 / Attempts last edited by Unkx80 on May 6, 2004 - 20:02
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