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 : 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 .
Black wins.
( at , at , at )

variation (2) after (8a)  

shevious: If White connects, Black wins the capturing race.
(White at 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 in (8'a) seems not to be the best, too.
( at )
Since White has no local ko threat, Black wins.
(If White moves at , 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 sente cannot be done before White .

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 ?

attempt (2)  

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

attempt (3a)  

a and b are miai.
Black works?

attempt (3b1)  

White is necessary to catch, but..

attempt (3b2)  

Black works?

attempt (3c1)  

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

attempt (3c2)  

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