Xuanxuan Qijing Problem 213 / Solution To Variation 1

Here are a few of the important sequences in this variation.

solution (5')  

Starting from solution (5) in the main solution, with the marked stone in place forcing the sequence up to here (well, almost ; there is another difficult variation starting with Black pushing and cutting, then driving White down with 7), the following is forced too :

solution (6)  
solution (7)  

But next it gets quite complicated (and I may still have missed something ; the full solution in sgf format soon to be found on my site : [ext] http://denisfeldmann.fr/bestiary.htm#emperor). I give only two examples:

solution (8a) (White escape or win easily the fight)  
variation (1) after (8a)  

shevious: I don't think White in (8a) wins or escapes.
If White goes to ko fight, Black has local ko threat at B7.
Black wins.
(B5 at white+circle, W8 at W4, B9 at black+circle)

variation (2) after (8a)  

shevious: If White connects, Black wins the capturing race.
(White W6 at B7 is just a repeat.)

Yes, sorry for that. It should have been :

solution (8'a) (White escape or win easily the fight)  

solution (9'a)  
varation to (8'a)  

shevious: Before that, Black B5 in (8'a) seems not to be the best, too.
(B11 at B5)
Since White has no local ko threat, Black wins.
(If White W6 moves at W12, then Black a works.)

dfeldmann?Yes, again I was oversimplifying (damn diagrams). Here is, I believe, the solution to your variation (but instead of only trying to demolish my solutions, you could try to mend them first :-)). Anyway, I am very grateful, for I had too quickly dismissed this option, and the final tesuji (sagari at 4 in diagram 10''a') is quite hard to find...

solution (8''a) (against the hane komi) : first play the 4-5 exchange  
solution (9''a) (a and b are miai), or  
solution (9''a')  
solution (10''a')  
solution (11''a') (2 right of 1, 6 takes back the ko)  
solution (8b)  
solution (9b) (I am quite proud of this last sequence)  

Attempts and comments

shevious: OK. I'll try to mend it if I can. :)
Actually, there are several moves that should be considered in the above solutions. I'll suggest some.

attempt (1) - sente?  

Black black+circle sente cannot be done before White W5.

solution (5'-fix)  

I think (5') is just a copying error from (5), but worth to be notified.
I mended it myself. :)

The Black's sente timing at a is delicate.

shevious: Then, what if Black goes back to ko fight after White W3?

attempt (2)  

If White connects at a, then it goes back to attempt (1).
Black escapes.

attempt (3a)  

a and b are miai.
Black black+circle works?

attempt (3b1)  

White W5 is necessary to catch, but..

attempt (3b2)  

Black black+circle works?

attempt (3c1)  

If White W5 at B8, Black to W7 and wins ko fight to make two eyes?

attempt (3c2)  

black+circle works as a net?
shevious: I have more candidates to consider, but let's solve it together one by one.
Any suggestions will be welcome.
f3etoiles: It is getting too hard to discuss this here; see your personal page for a parsonal message

Xuanxuan Qijing Problem 213 / Solution To Variation 1 last edited by IronChefSakai on November 11, 2016 - 21:20
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