Life In 19x19

fwiffo wrote:

$$B Ko
$$ | . . . . .
$$ | X X X , .
$$ | 4 O X . .
$$ | 3 O O X .
$$ | . 5 O X .
$$ | X . O X .
$$ | 1 O O X .
$$ | O X X O .
$$ | 2 . . O .
$$ | . O . . .
$$ | . . . . .
$$ ---------

Click Here To Show Diagram Code

[go]$$B Ko
$$ | . . . . .
$$ | X X X , .
$$ | 4 O X . .
$$ | 3 O O X .
$$ | . 5 O X .
$$ | X . O X .
$$ | 1 O O X .
$$ | O X X O .
$$ | 2 . . O .
$$ | . O . . .
$$ | . . . . .
$$ ---------[/go]

$$B Throw-in not working anymore
$$ | . . . . .
$$ | X X X , .
$$ | a O X . .
$$ | 3 O O X .
$$ | 4 5 O X .
$$ | X b O X .
$$ | 1 O O X .
$$ | O X X O .
$$ | 2 . . O .
$$ | . O . . .
$$ | . . . . .
$$ ---------

Click Here To Show Diagram Code

[go]$$B Throw-in not working anymore
$$ | . . . . .
$$ | X X X , .
$$ | a O X . .
$$ | 3 O O X .
$$ | 4 5 O X .
$$ | X b O X .
$$ | 1 O O X .
$$ | O X X O .
$$ | 2 . . O .
$$ | . O . . .
$$ | . . . . .
$$ ---------[/go]

White can do better.

quantumf wrote:

White A7

No real defence: If Black A3, White B6, and then lives at A9, or, if black approaches at A9, then white captures the two stones, and if black captures back, white plays B3

White can do better.

MountainGo wrote:

quantumf wrote:White A7

No real defence: If Black A3, White B6, and then lives at A9, or, if black approaches at A9, then white captures the two stones, and if black captures back, white plays B3

If Black A3, White can just A9, which gets a couple more points. So Black won't play A3 but rather A9 immediately, which forces White to capture two.

Bill Spight wrote:White can do better.

I continue to be stumped on this, though...

No, you got it right. if B A-03, W A-09, not W B-06. That's how White does better.

gonut wrote:Bill,

Great problem! I obviously don't know the correct answer to your question, because your White move seems to be better than the actual game. And a master wouldn't misplay an endgame, right?

In any event, here's my analysis, which in addition to $5 will get you a latte at a Starbucks:

(;
AB[aj][bj][cj][ck][dl][dm][dn][do][cp][bp]
AW[bk][bl][cl][cm][cn][co][bo][dp][dq][br];
B[an]
(;
W[ao]
C[The actual game.];
B[al];W[am];B[bm];W[bn];B[ak];W[am]
)
(;
W[ap]
C[Bill Spight's question: Black's response?]
(;
B[ao]
C[Best for Black.]
(;
W[am]
C[Best]
(;
B[ak]
C[Sente];
W[bn];B[al]
C[At the end of the game, Black may be able to take another point here. But Black is still a half point worse than in the actual game?]
)
(;
B[aq]
C[A mistake];
W[ak]
C[Black cannot avoid a shortage of liberties.];
B[bn];W[bq];B[ap];W[ar]
)
)
(;
W[bq]
C[Inferior];
B[aq];W[am];B[ak];W[bn];B[al]
C[Black pushes again in sente.]
)
(;
W[ak]
C[A mistake];
B[bm]
C[Black has a seki or a ko.]
)
(;
W[al]
C[A mistake];
B[aq];W[bq];B[ak];W[cq];B[ap];W[ar];B[bn]
C[Seki]
)
(;
W[aq]
C[A mistake.];
B[al]
C[Black has a ko.]
)
)
(;
B[ak]
C[2nd best for Black, but still one point worse for Black than the actual game.];
W[al]
C[Black does end in sente.];
B[aq]
C[Black cannot do any better.];
W[ao]
C[White is safe.]
)
(;
B[aq]
C[Fails];
W[ak]
C[Correct];
B[ao];W[am];B[bn];W[bq];B[ap];W[ar]
)
(;
B[al]
C[Fails];
W[ak]
(;
B[aq];W[am]
)
(;
B[bm];W[bq]
)
(;
B[ao];W[am];B[aq];W[bn]
)
)
)
)

Yes, for a while I thought that I had found a better move.

(;FF[4]GM[1]SZ[19]AP[GOWrite:2.2.21]ST[2]CA[ISO8859-1]PB[ ]PW[ ]FG[259:]AW[dp][dq][eq][fr][fs][br][bo][co][cn][cm][cl][bl][bk]PM[2]GN[ ]AB[cp][bp][do][dn][dm][dl][ck][cj][bj][aj]
;B[an]
;W[ap]
;B[aq]
;W[ak]
;C[Black has a better play here.]B[ao]
)

gonut wrote:Bill,

Doesn't my SGF above show the refutation of your most recent variation for Black? Viz., after the end of your variation, doesn't White A7 kill all the Black corner stones by keeping the Black stones in a shortage of liberties?

What am I missing?
Please be sure to type slow, I'm old.

And what is "zi"? (I don't really go to Starbucks.)

Myron

gonut wrote:Bill,

Doesn't my SGF above show the refutation of your most recent variation for Black? Viz., after the end of your variation, doesn't White A7 kill all the Black corner stones by keeping the Black stones in a shortage of liberties?

And what is "zi"? (I don't really go to Starbucks.)

Myron

topazg wrote:I think Black at B7 instead of capturing at A5 is Bill's point ?

Bill Spight wrote:

topazg wrote:I think Black at B7 instead of capturing at A5 is Bill's point ?

Yes.

This ko is lurking in the main line, as well. E. g., B A-06, W A-09, B B-07, W A-07. If White is komaster, White can play that way. But then Black will not start at A-06, either.