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End Game Test One Solution
  Difficulty: Dan level   Keywords: Problem, EndGame

Solution for "The Practical Endgame Test One"
See also EndGameTestOneSolution2 and EndGameTestOneSolution3.


[Diagram]
Diag.: White wins by 1 points

B1 is sente against the bottom w group, so W has to answer at 2. Next B cuts at 3 and reduces W even more.

B has sente to play the big point of 9 and W gets 10 next.


[Diagram]
Diag.: White wins by 1 points (continued)

B continues with 1 and W gets the last point with 6. 8 and 9 are necessary defense moves once all dame are filled in.

Count:

W has 4 points at the bottom (3+1 capture) 12 points at the top (11+1 prisoner)
B has 5 points on the left (4+1 capture) 10 points on the right (9+1 prisoner)
W wins by 1

--ArnoHollosi

DaveSigaty: W has not played as well as she could.



Ok, actually, this seems better for W:

[Diagram]
Diag.: White wins by 3 points

W plays 1 here instead of 10 in the previous diagram (2 here). So B plays 2 - I actually thought of this line, but somehow dismissed it, because 2 is bigger than 1. I didn't take the sente/gote relationship into account. After B10 the sequence continues with 'a' through 'd'. Now W wins by 3 points. --ArnoHollosi


[Diagram]
Diag.: White wins by a large margin

And if instead of 3 above White plays this? 6 connects? -- HolIgor


[Diagram]
Diag.: White wins by 4 points

Ok, so then black 2 here. If W answers at 3 & 5 she wins by 3 points. Hm, wait - W can play at 'a' now and force B to answer at 'b' then she plays 'c'. B cannot start the ko capturing with 'c' because black could not resist white 'd' after w 'b'. So white wins by 4 points. --ArnoHollosi



DaveSigaty: Most of the right ideas are coming out but there are more resources in this position than have shown up yet. Hint: the correct result is W wins by 4 points. But we haven't yet seen the correct order. For example, in the last diagram above B's play at 6 is not the best and B lets W get at least 1 more point than she should (I think!).

BTW, this problem looked fairly uncomplicated when I looked at it except for the tesuji in the lower left corner. However, in checking the solution I found that in the original readers' poll in Kido only 6% of the answers sent in were correct.


[Diagram]
Diag.: Another try: White wins by 3 points

Arno: I asked my high dan friend about this problem, and he came up with this new sequence on the right, which gives white sente. However, whichever variation we tried, white only wins by 3 points. I'm at my wits end. Enlighten me please.



Solution

[Diagram]
Diag.: The Answer Part 1

Dave Sigaty: This is the big stuff that Arno got right from the beginning...


[Diagram]
Diag.: Part 2 - W+4

The key point is W 2 here. B can't win the ko and would be forced to connect at a (allowing b) if he played away at 6 instead of connecting at 3. So W gets to come back for 4 and 6.



Dave: these problems should really have only a single line of correct play if they are good. In other words other choices by either B or W should lead to worse results for B or W respectivly.

Arno: for alternatives to B3 (in the above diagram) look at EndGameTestOneSolution2. (proving that this may not be a "good" problem)

Dave: for a more in depth analysis of another position that arose see EndGameTestOneSolution3.

Arno: new problem - alternative to B1 (in the last diagram). See EndGameTestOneSolution4



This is a copy of the living page "End Game Test One Solution" at Sensei's Library.
(C) the Authors, published under the OpenContent License V1.0.