Diff: Beginner Exercise 161 / Solution

BeginnerExercise161/Solution:page info & history, related pages, related changes

Current page:	version 6	modified on September 13, 2024 - 03:57	by hnishy
Archived page:	version 4	modified on October 23, 2022 - 06:47	by xela

Edit summary: "cleanup. Keep simple things simple"

Switch to diff-in-page view.

Diff: Beginner Exercise 161 / Solution

RecentChanges · StartingPoints · About

Edit page ·Search · Related · Page info · Latest diff

@@ -1,26 +1,30 @@	edit block
- KarlKnechtel: This looks to me a lot harder than exercise 162 or 163, so I thought I'd give it a shot. I'm pretty sure this is correct:
-
- $$B Black to play and live
+ $$B Solution
$$ . . . . . . . . . . . . . .
$$ . . . . . . . . . . . . . .
$$ . . . . O O O O O O . . . .
- $$ . . . . . . c 3 X . O . . .
- $$ . . . . O X c . d d O . . .
+ $$ . . . . . . . b X . O . . .
+ $$ . . . . O X . . . . O . . .
$$ . . O O . X X X X X . . . .
$$ . . O X X X O O O X O O . .
- $$ . . O X W W X X O O X O . .
- $$ . . O X e 2 f 1 b . a . . .
+ $$ . . O X O O X X O O X O . .
+ $$ . . O X . a . 1 . . . . . .
$$ ---------------------------

- B1 looks odd, but seems to be an example of [guzumi]. White cannot yet atari Black's [empty triangle] on either side, due to [damezumari] - White must play at a first before b. And since B2 would take the [vital point] of a [bulky five], White has no time for this capturing plan - she must play W2 herself, answering the empty triangle with one of her own.
+ B1! saves the stones most efficiently and lives, making ''a'' and ''b'' [miai] for an additional eye.

- That's the key; Black has now secured the bottom eye in [sente] (by threatening to make a second eye there), giving him time to complete the second eye at the top. B3 makes [miai] of the c's and of the d's.
-
- Later, White forces with Wa, Be, Wb, Bf. There is still lots of aji here! Note that Ba doesn't really help Black any, though it does give him one ko threat versus the several that White can get out of the position. W2 is better than playing it at 3, even though it fails; the points available to Black are the same, and White gets more threats. I don't think I'm qualified to compare W2 vs. tenuki, though.
-
- [xela]: "W2 is better than playing it at B3": I disagree! It's a little tricky to count the territory in either case, because you have to remember that eventually black will be forced to capture the WC stones, and you have to reassure yourself that there's no [under the stones] traps here. In the above diagram, black will end up with 7 points of territory (one point below B3, and 6 points for capturing three white stones). If white plays W2 at B3, then black will end up with 5 points of territory (two captives plus a point at ''f''), and there's also potential for white to capture the stone next to B3. Generally, you'd take the extra two points rather than worrying about the number of threats in a hypothetical future ko.
+ $$B Failure
+ $$ . . . . . . . . . . . . . .
+ $$ . . . . . . . . . . . . . .
+ $$ . . . . O O O O O O . . . .
+ $$ . . . . . . . 4 X . O . . .
+ $$ . . . . O X . . . . O . . .
+ $$ . . O O . X X X X X . . . .
+ $$ . . O X X X O O O X O O . .
+ $$ . . O X O O X X O O X O . .
+ $$ . . O X 3 1 . 2 . . . . . .
+ $$ ---------------------------

- Note that showing W2 in the solution diagram is good, because you want to check that you've read out all the variations and can find B3 if you need to. It's common that tsumego solutions show "the strongest resistance" rather than the moves you'd play in a real game.
+ B1 here is easily killed.

----