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 Post subject: Tactical Problems in Books #1 Posted: Sat May 13, 2023 11:26 am
 Judan

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Problem

In https://www.lifein19x19.com/viewtopic.p ... 67#p277667 I showed my invented problem from Tactical Reading, problem 40, page 181.

`[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.

`[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

`[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

`[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

`[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.

`[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.

`[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.

`[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

`[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

`[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

`[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]`

`[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]`

`[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

`[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!

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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.

`[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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