Endgame problem 29 / Attempts

Sub-page of EndgameProblem29
Alex's Attempt  

Alex Weldon: This seems to be best play for both sides, as far as I can tell. I don't see any way for White to do this in sente.

Hane and Connect  

SnotNose: White's only hope for sente is the hane and connect of W1 and W3. Compared to Alex's solution above, this result is four points better for Black, but White retains sente. Note that B4 isn't necessary for life so even this might not be sente for White. However, if Black omits B4, White can make a further reduction, as shown in the next diagram.

Black Tenuki  

SnotNose: If Black omits B4 of the previous diagram, White can play as shown. This is equivalent to Alex's solution (in terms of Black's area). A difference is that White has fully protected the right edge (i.e., Black cannot hane and connect to the right anymore.)

Success #1  

Velobici: Play on the point of symmetry is a proverb. W1 does just that, as does B2. At this point, White must be careful in choosing which way to move in connecting W1 to the outside, the two directions of not symmetrical. The marked black stone decreases White's liberty count if White plays at a in place of W3.

Black resists more strongly  

Black can resist more stongly with B2, protecting the weaker side of his position and trying for a shortage of liberties on W1. After B6, White faces a connect and die situation.

Success #2  

White must sacrifice a stone with W3, forcing Black to connect with B3, and preventing Black from creating the connect and die. Black can not play at a due to his own shortage of liberties. This allows White to connect at the point formerly occupied by B6 and at b. Black will live by playing at c, forcing White to connect at the point formerly occupied by B6. Black then plays at a, forming his second eye by capturing W3 and forcing White to connect at b.

Correct for both?  

dnerra: Looking at everything proposed so far, it seems to me that this is the correct sequence for both. After W5, Black can tenuki, as White cannot play at B8 himself. Black has to add the exchange B8-W9 at some time when it has become sente and before he has lost his liberties all around. Since Black a-White b can be counted as Black's priviledge, this seems approximately one point better for Black than the sequence suggested above as optimal for both sides.

Dieter: Aside from the tenuki issue, this is indeed the solution we found when watching the game on KGS. Note that White can't play W7 at B8 due to shortage of liberties. In the game, joeker? missed W3, either or not deliberately since he was winning anyway.

Bill: W3 is indeed a nice play. I would be happy to find it in a game. :-) B8 and W9 are miai. I calculate W1 - W5 to be a 2.5 point gote (miai counting).

If White wishes to retain sente, he can play as in the Black resists more strongly diagram. That loses only 1/6 of a point.

Endgame problem 29 / Attempts last edited by BillSpight on December 26, 2003 - 20:33
RecentChanges · StartingPoints · About
Edit page ·Search · Related · Page info · Latest diff
[Welcome to Sensei's Library!]
Search position
Page history
Latest page diff
Partner sites:
Go Teaching Ladder
Login / Prefs
Sensei's Library