Life In 19x19

One of my old problems, which some people will recall.

Click Here To Show Diagram Code

[go]$$Wc White to play and win
$$ ---------------
$$ | . . . . . . . |
$$ | . O O O O O . |
$$ | . O X . X O O |
$$ | O X X . X . . |
$$ | O X . X . X . |
$$ | O X X . X X . |
$$ | . . . . . . . |
$$ ---------------[/go]

No komi.

Enjoy!

NoSkill wrote:

$$Wc White to play and win
$$ ---------------
$$ | . . . . . . . |
$$ | . O O O O O . |
$$ | . O X 3 X O O |
$$ | O X X . X . . |
$$ | O X . X . X 1 |
$$ | O X X . X X 2 |
$$ | . . . . . . . |
$$ ---------------

Click Here To Show Diagram Code

[go]$$Wc White to play and win
$$ ---------------
$$ | . . . . . . . |
$$ | . O O O O O . |
$$ | . O X 3 X O O |
$$ | O X X . X . . |
$$ | O X . X . X 1 |
$$ | O X X . X X 2 |
$$ | . . . . . . . |
$$ ---------------[/go]

Why did you stop at that point?

Bill Spight wrote:

NoSkill wrote:

$$Wc White to play and win
$$ ---------------
$$ | . . . . . . . |
$$ | . O O O O O . |
$$ | . O X 3 X O O |
$$ | O X X . X . . |
$$ | O X . X . X 1 |
$$ | O X X . X X 2 |
$$ | . . . . . . . |
$$ ---------------

Click Here To Show Diagram Code

[go]$$Wc White to play and win
$$ ---------------
$$ | . . . . . . . |
$$ | . O O O O O . |
$$ | . O X 3 X O O |
$$ | O X X . X . . |
$$ | O X . X . X 1 |
$$ | O X X . X X 2 |
$$ | . . . . . . . |
$$ ---------------[/go]

Why did you stop at that point?

No way for black really from there

NoSkill wrote:

Bill Spight wrote:

NoSkill wrote:

$$Wc White to play and win
$$ ---------------
$$ | . . . . . . . |
$$ | . O O O O O . |
$$ | . O X 3 X O O |
$$ | O X X . X . . |
$$ | O X . X . X 1 |
$$ | O X X . X X 2 |
$$ | . . . . . . . |
$$ ---------------

Click Here To Show Diagram Code

[go]$$Wc White to play and win
$$ ---------------
$$ | . . . . . . . |
$$ | . O O O O O . |
$$ | . O X 3 X O O |
$$ | O X X . X . . |
$$ | O X . X . X 1 |
$$ | O X X . X X 2 |
$$ | . . . . . . . |
$$ ---------------[/go]

Why did you stop at that point?

No way for black really from there

True enough. But I was hoping that you would refer to the miai. The board is not scorable, but play is essentially over.

Good problem, Bill. I have to ask, though... Why are so many of your problems "cute"?

Kirby wrote:Good problem, Bill. I have to ask, though... Why are so many of your problems "cute"?

Because they are small with funny wrinkles.

Click Here To Show Diagram Code

[go]$$Wc White to play and win
$$ ---------------
$$ | . . . . . . . |
$$ | . O O O O O . |
$$ | . O X a X O O |
$$ | O X X . X . . |
$$ | O X . X . X b |
$$ | O X X . X X . |
$$ | . . . . . . . |
$$ ---------------[/go]

The cute wrinkle here is that "a" and "b" look like miai, familiar gote plays that gain 1/2 point each.

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[go]$$Wc Miai?
$$ ---------------
$$ | . . . . . . . |
$$ | . O O O O O . |
$$ | . O X 4 X O O |
$$ | O X X . X . 3 |
$$ | O X . X . X 1 |
$$ | O X X . X X 2 |
$$ | . . . . . . . |
$$ ---------------[/go]

The wrinkle is that "a" and "b" are not independent. They form a combination that gains more than 1/2. In fact, it gains 7/12.

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[go]$$Bc Black first
$$ ---------------
$$ | . . . . . . . |
$$ | . O O O O O . |
$$ | . O X 1 X O O |
$$ | O X X a X . . |
$$ | O X . X . X b |
$$ | O X X . X X c |
$$ | . . . . . . . |
$$ ---------------[/go]

makes 1 pt. at "a" and leaves the 1/2 pt. gote at "b", so that we count "c" as 1/2 pt. The sum of the two is 1.5 pt. (for Black).

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[go]$$Wc White first
$$ ---------------
$$ | . . . . . . . |
$$ | . O O O O O . |
$$ | . O X 3 X O O |
$$ | O X X . X . . |
$$ | O X . X . X 1 |
$$ | O X X . X X 2 |
$$ | . . . . . . . |
$$ ---------------[/go]

In this combination does not connect, but returns to the center. There is a hidden ko in the right side, worth 1/3 pt. (for Black).

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[go]$$Bc Black follow-up
$$ ---------------
$$ | . . . . . . . |
$$ | . O O O O O . |
$$ | . O X O X O O |
$$ | O X X 3 X 2 1 |
$$ | O X . X . X W |
$$ | O X X . X X X |
$$ | . . . . . . . |
$$ ---------------[/go]

@

After takes , forces . Then takes .

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[go]$$Bc Result
$$ ---------------
$$ | . . . . . . . |
$$ | . O O O O O . |
$$ | . O X O X O O |
$$ | O X X X X O . |
$$ | O X . X . X W |
$$ | O X X . X X X |
$$ | . . . . . . . |
$$ ---------------[/go]

The exchange of the two stones cancels out. The ko stone, , is worth 1/3 pt. to Black.

For the White follow-up White simply connects, gaining 1/3 pt. for a count of 0.

The original count of that region is 11/12 for Black. Black to play gains 7/12, for a count of 1.5. White to play gains 7/12, for a count of 1/3.