Problem
In https://www.lifein19x19.com/viewtopic.p ... 67#p277667 I showed my invented problem from Tactical Reading, problem 40, page 181.
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[go]$$W White to move
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X . X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O . . . . . . . O .
$$. . . X X . X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
First Move Candidates
For solving the problem by tactical reading, identify the interesting first move candidates. Other moves are obviously inferior.
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[go]$$W first move candidates
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X c X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O g f . b . d e O .
$$. . . X X a X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
White's Start I
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X C X X O .
$$. . O X O X . X . O .
$$. O 6 X X X X X . O .
$$. O 4 3 . 2 . C . O .
$$. . 5 X X 1 X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
White's continuation on a marked intersection or reversions fail so White 1 fails.
White's Start II
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[go]$$W a = 10...
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X 3 X X O .
$$. . O X O X . X . O .
$$. O 6 X X X X X a O .
$$. O 4 . 7 1 b . 8 O .
$$. . 5 X X 2 X X 9 O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black 2 is correct. White achieves a gote seki.
White's Start III
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X 1 X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O . . . 2 . . . O .
$$. . . X X . X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black 2 is correct.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X O X X O .
$$. . O X O X . X . O .
$$. O . X X X X X b O .
$$. O 3 4 . X . 6 5 O .
$$. . . X X . X X a O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Instead of White 3, a - 6 and b - 6 also fail.
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[go]$$W a = 10...
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X O X X O .
$$. . O X O X . X . O .
$$. O c X X X X X 8 O .
$$. O 4 3 e X a 5 6 O .
$$. . b X X 9 X X 7 O .
$$. O . d O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
A reversion also fails.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X O X X O .
$$. . O X O X . X . O .
$$. O 8 X X X X X . O .
$$. O 6 5 . X . 4 . O .
$$. . 7 X X 3 X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black 4 is the simplest move establishing life and prevents White 4. White 3 fails.
Since all White 3s fail, White 1 fails.
White's Start IV
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X 2 X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O C C . C C 1 C O .
$$. . . X X C X X C O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
White's next move on one of the labelled intersections fails so White 1 fails.
White's Start V
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X 2 X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O C C . C . C 1 O .
$$. . . X X C X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
White's next move on one of the labelled intersections fails so White 1 fails.
White's Start VI
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X . X X O .
$$. . O X O X . X . O .
$$. O 4 X X X X X . O .
$$. O 2 1 . . . . . O .
$$. . 3 X X . X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X 5 X X O .
$$. . O X O X . X . O .
$$. O X X X X X X . O .
$$. O X O . . . 8 7 O .
$$. . O X X 6 X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X C X X O .
$$. . O X O X . X . O .
$$. O X X X X X X . O .
$$. O X O . 6 . C . O .
$$. . O X X 5 X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
White's next move on one of the labelled intersections fails so White 5 fails.
Both White 5s fails so White 1 fails.
White's Start VII
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X . X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O 1 . . . . . . O .
$$. . . X X . X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Each of the correct next black moves allows White 1 to capture typically the lower left black string. This is 6 ~ 8 points better for White than the seki and both results should be White's gote. 6 ~ 8 points better equals half a rank. In other problems with decisions between life or death of all stones, such can be worth a difference of two or three ranks. Proper tactical reading is mandatory in such problems!
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X C X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O O 2 . 3 . . . O .
$$. . . X X C X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black's next move on one of the labelled intersections fails so Black 2 fails.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X 3 X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O O 4 . 7 . 6 5 O .
$$. . . X X 2 X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black 2 is wrong.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X 3 X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O O 4 . 5 7 . 2 O .
$$. . . X X 6 X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black's variations also fail. Black 2 is wrong.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X 3 X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O O 7 . 6 2 . 4 O .
$$. . . X X 5 X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black 2 is wrong.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X . X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O O . . 2 . . . O .
$$. . . X X . X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black 2 allows White to capture the lower left black string.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X 3 X X O .
$$. . O X O X . X . O .
$$. O . X X X X X 8 O .
$$. O O 4 . X . 5 6 O .
$$. . . X X . X X 7 O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
White 3 does not capture any black stone.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X 5 X X O .
$$. . O X O X . X . O .
$$. O . X X X X X 8 O .
$$. O O 4 . X . 3 6 O .
$$. . . X X . X X 7 O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
White 3 does not capture any black stone.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X 6 X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O O 4 . X . 5 . O .
$$. . . X X 3 X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
White 3 does not capture any black stone.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X 4 X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O O 3 7 X . 6 . O .
$$. . . X X 5 X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black 6 is the simplest move enabling life for most black stones. Instead, Black 7 - 6 is wrong. The correct White 3 captures the lower left black string so this is the result of the preceding Black 2.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X 2 X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O O . . . . . . O .
$$. . . X X 3 X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
White 3 is correct. Black 2 allows White to capture the lower left black string because this is the result of both Black 4s.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X X X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O O 5 . 4 . . . O .
$$. . . X X O X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black 4 allows White to capture the lower left black string.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X X X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O O O 7 X . . 6 O .
$$. . . X X O X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black 6 is correct. White captures the lower left black string. This is the result of the preceding Black 4.
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[go]$$W a = 10...
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X X X X O .
$$. . O X O X . X . O .
$$. O . X X X X X b O .
$$. O O O 6 X a 7 8 O .
$$. . . X X O X X 9 O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black 6 fails.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X X X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O O . . . . . 4 O .
$$. . . X X O X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black 4 allows White to capture the lower left black string with any of his correct next moves.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X X X X O .
$$. . O X O X . X . O .
$$. O . X X X X X d O .
$$. O O a . b c . X O .
$$. . . X X O X X 5 O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Next, Black avoids Black a to d.
Each of Black's correct next moves allows White to capture the lower left black string so this is the result of White 5.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X X X X O .
$$. . O X O X . X . O .
$$. O . X X X X X 8 O .
$$. O O 7 9 6 b a X O .
$$. . . X X O X X O O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Instead of move 8, Black avoids Black 9 - a - b - 8 and Black 9 - a - 8 - b.
Black 6 allows White to capture the lower left black string.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X X X X O .
$$. . O X O X . X . O .
$$. O . X X X X X 6 O .
$$. O O 7 9 8 b a X O .
$$. . . X X O X X O O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Instead of move 8, Black avoids Black 9 - b. Instead of move 7, e.g., White b - 8 - 7 - a - 9 is also possible.
Black 6 allows White to capture a black string.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X X X X O .
$$. . O X O X . X . O .
$$. O . X X X X X 5 O .
$$. O O a . b c . X O .
$$. . . X X O X X d O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Next, Black avoids Black a to d.
Each of Black's next moves allows White to capture the lower left black string so this is the result of White 5.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X X X X O .
$$. . O X O X . X . O .
$$. O . X X X X X O O .
$$. O O . . . . . X O .
$$. . . X X O X X 6 O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black 6 allows White to capture either lower black string but White can choose sente.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X X X X O .
$$. . O X O X . X . O .
$$. O . X X X X X O O .
$$. O O a b 8 7 c X O .
$$. . . X X O X X X O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
White a - c - b or White c - a (White's sente) capture either lower black string so this is the result of White 7.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X X X X O .
$$. . O X O X . X . O .
$$. O . X X X X X O O .
$$. O O 7 9 8 a . X O .
$$. . . X X O X X X O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Instead of move 8, Black 9 - a results in the death of the black group. White 7 captures the lower left black string.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X X X X O .
$$. . O X O X . X . O .
$$. O . X X X X X O O .
$$. O O 7 9 6 . a X O .
$$. . . X X O X X 8 O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black 6 is correct: White can only capture in gote. Black 8 at 9 is countered by White a, which kills the black group. Black 6 allows White to capture the lower left black string.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X X X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O O 5 . . . . X O .
$$. . . X X O X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
White 5 captures the lower left black string because this is the result of Black's correct reply.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X X X X O .
$$. . O X O X . X . O .
$$. O . X X X X X . O .
$$. O O O 7 6 . . X O .
$$. . . X X O X X . O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
The correct Black 6 allows White to capture the lower left black string.
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[go]$$W
$$. . . . . . . . . . .
$$. . . . . O O O O . .
$$. . O O O X X X X O .
$$. . O X O X . X . O .
$$. O . X X X X X d O .
$$. O O O 6 a b c X O .
$$. . . X X O X X 7 O .
$$. O . . O O O O O . .
$$. . O . . . . . . . .
$$ . . . . . . . . . .[/go]
Black a - c - b - d, Black a - c - d - b, Black b - d, Black c - a and Black d - b fail so Black 6 results in the death of the black group.
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