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Tsumego thinking log

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Tsumego thinking log

Posted: Fri Jul 14, 2017 11:51 am
by Calvin Clark
Upon reflecting on my recent games, I must draw the conclusion that I'm
infected with blitz thinking. When I get this way, simple tsumego only
make things worse, and I have to crank on ones that require more thinking.
This one is marked "advanced" in TsumeGo Pro, but I actually don't think
it's advanced. Still, I took some time to think about it more thoroughly,
rather that going with my instinct move. My thinking is under the hide tag.

Problem 1
Click Here To Show Diagram Code
[go]$$B Black to play
$$ ------------
$$ | . X . . . .
$$ | . O X X . .
$$ | . . O X . .
$$ | . . O X . .
$$ | . O X O O .
$$ | . O X . . .
$$ | O X X . O .
$$ | . O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
The first thing I notice is that black has only three liberties. Next I see
that white has a lot of cutting points, and black has a double atari at 'a'.
Click Here To Show Diagram Code
[go]$$B Black to play
$$ ------------
$$ | . X . . . .
$$ | . O X X . .
$$ | . a O X . .
$$ | . . O X . .
$$ | . O X O O .
$$ | . O X S . .
$$ | O X X S O .
$$ | . O X S . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
Exploratory reading reveals the double atari isn't promising immediately.
Click Here To Show Diagram Code
[go]$$B Black to play
$$ ------------
$$ | . X . . . .
$$ | 3 O X X . .
$$ | . 1 O X . .
$$ | . 2 O X . .
$$ | . O X O O .
$$ | . O X 4 . .
$$ | O X X . O .
$$ | . O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
2nd exploratory reading shows white can't play at either 'a' or 'b', so at
first this looks promising.
Click Here To Show Diagram Code
[go]$$B Black to play
$$ ------------
$$ | . X . . . .
$$ | . O X X . .
$$ | a 2 O X . .
$$ | 3 1 O X . .
$$ | b O X O O .
$$ | . O X . . .
$$ | O X X . O .
$$ | . O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
But looking at liberties, it seems black has to fill three liberties to put
white in atari and white has to fill three to put black in atari. Since it's
white's move, this doesn't work for black. (Reading a sequence of alternating
triangles and squares while holding this starting position in my head takes
effort, but in this case I don't have to do it that way. I can just count.)

Discouraged, I take a nap.
Click Here To Show Diagram Code
[go]$$W
$$ ------------
$$ | T X T . . .
$$ | T O X X . .
$$ | . O O X . .
$$ | X X O X . .
$$ | S O X O O .
$$ | S O X . . .
$$ | O X X . O .
$$ | S O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
On my first reading, I don't see that if white plays :w1:, :b2: is atari.
Click Here To Show Diagram Code
[go]$$W
$$ ------------
$$ | . X . . . .
$$ | . O X X . .
$$ | 2 O O X . .
$$ | X X O X . .
$$ | . O X O O .
$$ | 1 O X . . .
$$ | O X X . O .
$$ | . O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
I also didn't notice this:
Click Here To Show Diagram Code
[go]$$W
$$ ------------
$$ | . X . . . .
$$ | . O X X . .
$$ | . W O X . .
$$ | X B O X . .
$$ | 2 O X O O .
$$ | . O X 1 . .
$$ | O X X . O .
$$ | . O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
Is it looking like this cut at :bc: is promising. :bc: is forcing and white has no other response but :wc:.

At last, verify that white has no way to stop both 'a' and 'b'.
Click Here To Show Diagram Code
[go]$$W
$$ ------------
$$ | . X . . . .
$$ | . O X X . .
$$ | a O O X . .
$$ | X X O X . .
$$ | b O X O O .
$$ | . O X . . .
$$ | O X X . O .
$$ | . O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]

Re: Tsumego thinking log

Posted: Fri Jul 14, 2017 3:19 pm
by Kirby
It's an interesting thought process. I'd say the biggest difference between my thoughts and yours is that I almost treat this as an end state immediately:
Click Here To Show Diagram Code
[go]$$B Black to play
$$ ------------
$$ | . X . . . .
$$ | . O X X . .
$$ | a 2 O X . .
$$ | 3 1 O X . .
$$ | b O X O O .
$$ | . O X . . .
$$ | O X X . O .
$$ | . O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
I don't consciously count liberties. This shape just seems to be in my pattern recognition database or something. Since this is an end state at a glance, it's much easier to look for weak points in white's shape.

I don't know what makes this an "end state" for me. I wish more shapes that I have to consciously think about were "end states", too.

Maybe it's just a matter of doing more problems.

Posted: Fri Jul 14, 2017 8:32 pm
by EdLee
Hi Calvin, Thanks for posting interesting shapes.
( If you separate the original shape in a stand-alone post,
then people can [quote] with no worries of your hidden text. )
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . O . O . . . .
$$ | . X X X O . . . O , .
$$ | . X O O X X X X O . .
$$ | X O . . O O X O O . .
$$ | . . . . . . O . . . .
$$ -----------------------[/go]
First feeling, the chicken shape, so W cannot approach:
( If this fails, then I read something else. )
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . O . O . . . .
$$ | . X X X O . . . O , .
$$ | . X O O X X X X O . .
$$ | X O 2 1 O O X O O . .
$$ | . . . 3 . . O . . . .
$$ -----------------------[/go]
Click Here To Show Diagram Code
[go]$$B var 1. B kills
$$ | . . . . O . O . . . .
$$ | . X X X O . . . O , .
$$ | . X O O X X X X O . .
$$ | X O 2 1 O O X O O . .
$$ | . 4 . 3 . 5 O . . . .
$$ -----------------------[/go]
Click Here To Show Diagram Code
[go]$$B var 2. B kills
$$ | . . . . O . O . . . .
$$ | . X X X O . . . O , .
$$ | . X O O X X X X O . .
$$ | X O 2 1 O O X O O . .
$$ | . . 5 3 . 4 O . . . .
$$ -----------------------[/go]
As Bill points out, below, B should tenuki in var 2;
and if B wants to atari, the hane is better:
Click Here To Show Diagram Code
[go]$$B var 2a
$$ | . . . . O . O . . . .
$$ | . X X X O . . . O , .
$$ | . X O O X X X X O . .
$$ | X O 2 1 O O X O O . .
$$ | . 5 . 3 . 4 O . . . .
$$ -----------------------[/go]
IMG_0053.JPG
IMG_0053.JPG (92.67 KiB) Viewed 20382 times

Re: Tsumego thinking log

Posted: Fri Jul 14, 2017 8:52 pm
by Calvin Clark
@Kirby, I have to be careful of my terminal states, as this problem shows.

This is a class B problem from 手筋事典

Problem 2
Click Here To Show Diagram Code
[go]$$B Black to play
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . X . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . Q . . . . . . . . . . . . . . . . |
$$ | . . . Q . . . . . . . . . . . . O . . |
$$ | . . X . . X X O . . . . . . . . . . . |
$$ | . . X X X X O O . , . . . . . X X . . |
$$ | . O X O O O . . . . . . X . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Big hint:
It's in a section titled: コスミ

My reading:
First, the aim is to attack the marked white stones. That being said, black's lower left group has no eyes and can't afford to become a target. Attempts to connect under with moves like 'a' are not part of the aim. :b1: is the natural move even without the hint. Softer moves like 'b' or 'c' would let white out more easily.
Click Here To Show Diagram Code
[go]$$B Black to play
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . X . b . . . . . . . . . . . O . . |
$$ | . . . 1 c . . . . . . . . . . . . . . |
$$ | . a Q . . . . . . . . . . . . . . . . |
$$ | . . . Q . . . . . . . . . . . . O . . |
$$ | . . X . . X X O . . . . . . . . . . . |
$$ | . . X X X X O O . , . . . . . X X . . |
$$ | . O X O O O . . . . . . X . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
My first reading is if white tries to escape fast with :w2: After :b5:, as long as the ataris at 'a' and 'b' aren't helping white, this seems fine for black.
Click Here To Show Diagram Code
[go]$$B First feeling
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . X . . . . . . . . . . . . . O . . |
$$ | . . . 1 a . . . . . . . . . . . . . . |
$$ | . . Q b 3 2 . . . . . . . . . . . . . |
$$ | . . . Q 4 5 . . . . . . . . . . O . . |
$$ | . . X . . X X O . . . . . . . . . . . |
$$ | . . X X X X O O . , . . . . . X X . . |
$$ | . O X O O O . . . . . . X . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Other ways for white to escape seem too slow, but I checked this one. I considered this "terminal" after :b3:, because 'a' and 'b' are miai.
Click Here To Show Diagram Code
[go]$$B Check a worse move for white.
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . X . . . . . . . . . . . . . O . . |
$$ | . . . 1 . . . . . . . . . . . . . . . |
$$ | . . Q 3 2 . . . . . . . . . . . . . . |
$$ | . . a Q b . . . . . . . . . . . O . . |
$$ | . . X . . X X O . . . . . . . . . . . |
$$ | . . X X X X O O . , . . . . . X X . . |
$$ | . O X O O O . . . . . . X . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
But the book suggests I should look further. What about :w1:? If black 'a', white 'b' and black is not as well off. I did not read this far. It turns out black can handle this :w1:, but frankly if I couldn't see how when playing :bc:, this could a problem in a game. Shallow reading.
Click Here To Show Diagram Code
[go]$$W
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . X . . . . . . . . . . . . . O . . |
$$ | . . . B . . . . . . . . . . . . . . . |
$$ | . . Q X O . . . . . . . . . . . . . . |
$$ | . . O Q X 1 b . . . . . . . . . O . . |
$$ | . . X . a X X O . . . . . . . . . . . |
$$ | . . X X X X O O . , . . . . . X X . . |
$$ | . O X O O O . . . . . . X . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Re:

Posted: Fri Jul 14, 2017 8:53 pm
by Calvin Clark
EdLee wrote:Hi Calvin, Thanks for posting interesting shapes.
( If you separate the original shape in a stand-alone post,
Good suggestion! I missed this post just now, but will do that next time.

Posted: Fri Jul 14, 2017 9:00 pm
by EdLee
Hi Calvin,
These two are slightly different, I think...
Click Here To Show Diagram Code
[go]$$B var 1
$$ | . . . . O . O . . . .
$$ | . X X X O . . . O , .
$$ | . X O O X X X X O . .
$$ | X O O X O O X O O . .
$$ | . O . X . 5 O a . . .
$$ -----------------------[/go]
Click Here To Show Diagram Code
[go]$$B var 2
$$ | . . . . O . O . . . .
$$ | . X X X O . . . O , .
$$ | . X O O X X X X O . .
$$ | X O O X O O X O O . .
$$ | . O . X 5 . O . . . .
$$ -----------------------[/go]
Var 1: B can remove the :white: stone with 1 move, (a).
Var 2: B needs 2 moves to do it.

Var 2: W (a) could be an immediate threat.
Var 1: Nope.

Re: Tsumego thinking log

Posted: Fri Jul 14, 2017 10:18 pm
by Bill Spight
Calvin Clark wrote:My thinking is under the hide tag.
Click Here To Show Diagram Code
[go]$$B Black to play
$$ ------------
$$ | . X . . . .
$$ | . O X X . .
$$ | . . O X . .
$$ | . . O X . .
$$ | . O X O O .
$$ | . O X . . .
$$ | O X X . O .
$$ | . O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
A few comments. :)
Calvin Clark wrote:The first thing I notice is that black has only three liberties. Next I see that white has a lot of cutting points, and black has a double atari at 'a'.
Click Here To Show Diagram Code
[go]$$B Black to play
$$ ------------
$$ | . X . . . .
$$ | . O X X . .
$$ | . a O X . .
$$ | . . O X . .
$$ | . O X O O .
$$ | . O X S . .
$$ | O X X S O .
$$ | . O X S . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
It also helps to count the dame of the White stones, even though, as you know, dame are not everything.
Exploratory reading reveals the double atari isn't promising immediately.
Click Here To Show Diagram Code
[go]$$B Black to play
$$ ------------
$$ | . X . . . .
$$ | 3 O X X . .
$$ | . 1 W X . .
$$ | . 2 W X . .
$$ | . O X O O .
$$ | . O X 4 . .
$$ | O X X . O .
$$ | . O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
The :wc: stones had two dame, but after :w2: they have three. Not a promising start, as you say. :)

However, :w4: is a mistake.
Click Here To Show Diagram Code
[go]$$Bc Throw-in and ko
$$ ------------
$$ | . X . . . .
$$ | 3 O X X . .
$$ | . 1 O X . .
$$ | 7 2 O X . .
$$ | 6 O X O O .
$$ | 5 O X 4 . .
$$ | O X X . O .
$$ | . O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
:w4: in the next diagram is correct.
Click Here To Show Diagram Code
[go]$$Bc No ko
$$ ------------
$$ | . X . . . .
$$ | 3 O X X . .
$$ | . 1 O X . .
$$ | . 2 O X . .
$$ | . O X O O .
$$ | 4 O X . . .
$$ | O X X . O .
$$ | . O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
2nd exploratory reading shows white can't play at either 'a' or 'b', so at
first this looks promising.
Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ------------
$$ | . X . . . .
$$ | . O X X . .
$$ | a 2 O X . .
$$ | 3 1 O X . .
$$ | b O X O O .
$$ | . O X . . .
$$ | O X X . O .
$$ | . O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
But looking at liberties, it seems black has to fill three liberties to put
white in atari and white has to fill three to put black in atari. Since it's
white's move, this doesn't work for black. (Reading a sequence of alternating
triangles and squares while holding this starting position in my head takes
effort, but in this case I don't have to do it that way. I can just count.)

Discouraged, I take a nap.
Click Here To Show Diagram Code
[go]$$Wc
$$ ------------
$$ | T X T . . .
$$ | T W X X . .
$$ | . W W X . .
$$ | B B W X . .
$$ | S O X O O .
$$ | S O X . . .
$$ | O X X . O .
$$ | S O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
The :wc: stones have only two dame. Which, it turns out, are its only liberties. There are two ways that a unit of connected stones with only two dame, without help from nearby stones, can have more than two liberties. One is if it includes a stone on a 1-2 point, and the other is if one of its dame is in an eye. The :bc: stones have only two dame and have no eye, but have four liberties because of help from nearby stones. :) If the :wc: stones descend to the 1-2 point, they will have two dame but three liberties. (Black can connect at C-19 and reduce the liberties back to two.)

On my first reading, I don't see that if white plays :w1:, :b2: is atari.
Click Here To Show Diagram Code
[go]$$W
$$ ------------
$$ | . X . . . .
$$ | a W X X . .
$$ | 2 W W X . .
$$ | B B W X . .
$$ | . O X O O .
$$ | 1 O X . . .
$$ | O X X . O .
$$ | . O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
Since the :wc: stones have only two liberties and the :bc: stones have three liberties, :b2: is unnecessary now. Also, "a" is a slightly better way to atari the :wc: stones, in case Black ignores a ko threat.
I also didn't notice this:
Click Here To Show Diagram Code
[go]$$Wc
$$ ------------
$$ | . X . . . .
$$ | . O X X . .
$$ | . O O X . .
$$ | X X O X . .
$$ | 2 O X O O .
$$ | . O X 1 . .
$$ | O X X . O .
$$ | . O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
:b2: in the next diagram is correct.
Click Here To Show Diagram Code
[go]$$Wc
$$ ------------
$$ | . X . . . .
$$ | . O X X . .
$$ | . O O X . .
$$ | X X O X . .
$$ | . O X O O .
$$ | 2 O X 1 . .
$$ | O X X . O .
$$ | a O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
Note that connecting at "a" is not sente. :)
Is it looking like this cut at :bc: is promising. :bc: is forcing and white has no other response but :wc:.

At last, verify that white has no way to stop both 'a' and 'b'.
Click Here To Show Diagram Code
[go]$$W
$$ ------------
$$ | . X . . . .
$$ | . O X X . .
$$ | a O O X . .
$$ | X X O X . .
$$ | b O X O O .
$$ | . O X . . .
$$ | O X X . O .
$$ | . O X . . .
$$ | . O O O . .
$$ | . . . , . .
$$ | . . . . . .[/go]
This kind of position is called Golden Cock Stands on One Leg, a poetic name that suggests how it looks. :D

Posted: Fri Jul 14, 2017 10:55 pm
by EdLee
Hi Bill,

Unhidden one sentence, hopefully without any spoilers:
...more than two liberties. One is if it includes a stone on a 1-2 point,
and the other is if one of its dame is in an eye.
Does dame here mean PrimaryLiberty ?

Does liberties here mean SecondaryLiberty ?

Could you show an example (or two? :)) of the eye situation ?
Click Here To Show Diagram Code
[go]$$B ?
$$ | . . . . . . . . . . . |
$$ | O O O O O O . O O O O |
$$ | X X X X X O O O X X X |
$$ | O O X . X O X X X . O |
$$ | . O . X X O X . X O . |
$$ -------------------------[/go]
Thanks.

Re: Tsumego thinking log

Posted: Sat Jul 15, 2017 7:51 am
by Calvin Clark
From 前田詰碁集

This one's a bit harder (or at least deeper). As EdLee suggests, I'll post the problem first.

Problem 3
Click Here To Show Diagram Code
[go]$$W White to play
$$ -------------------
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . , . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . X . . . . . . .
$$ | . O X X O O . . .
$$ | . X O O X X O . .
$$ | . . O , X . X . .
$$ | . O O X X . . . .
$$ | . O X O O O O . .
$$ | . X X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . , . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ ------------------[/go]

Re: Tsumego thinking log

Posted: Sat Jul 15, 2017 8:08 am
by Calvin Clark
Thanks @EdLee, and @Bill Spight for showing some of the defects in my reading. Please continue doing so! I should put out a disclaimer for anyone viewing this thread that I am in no way attempting to post authoritative solutions to the problems shown. Quite the opposite, The goal is rather to sort out---with the help of other SL members---
the things that tend to trip me up after a few moves have been read. Sometimes the issue will be clear to me once an intermediate position is reached and put into a solid diagram, and other times I may still miss it even when it's staring me in the face. Weaker players will not learn much from what I am saying except perhaps how to beat me :oops: or (more positively) that you are not alone.

Feel free also share the hallucinations that bother you in some positions, or other tips that help you decide what to look at first. Two (or more?) ways in which my bad style made my reading less efficient that it could be have been pointed out in a single problem! I am beginning to appreciate why Mingjiu Jiang 7p gave the advice: "do problems with a friend." Working alone, you can really fool yourself.

Posted: Sat Jul 15, 2017 12:43 pm
by EdLee
First feeling: run once. Read later... :study:
Click Here To Show Diagram Code
[go]$$W
$$ | . . . . . . . . . . . . . .
$$ | . . . . . . . . O X . O . .
$$ | . . . . . . . O X . . O . .
$$ | . . . . . . . O X X X O . .
$$ | . . . , . . . X O , X O . .
$$ | . . . . . . . X O O O X X .
$$ | . . . . . . X O X . O O X .
$$ | . . . . . . . 1 . . . . . .
$$ -----------------------------[/go]
Another try: :study:

Re:

Posted: Sat Jul 15, 2017 1:11 pm
by Cassandra
@ EdLee
EdLee wrote:First feeling: run once. Read later... :study:
Click Here To Show Diagram Code
[go]$$W
$$ -------------------
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . , . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . X . . . . . . .
$$ | 1 O X X O O . . .
$$ | . X O O X X O . .
$$ | . . O , X . X . .
$$ | . O O X X . . . .
$$ | . O X O O O O . .
$$ | . X X . . . . . .
$$ | . . . . . . . . .[/go]
Click Here To Show Diagram Code
[go]$$W
$$ -------------------
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . , . . . . .
$$ | . . . . . . . . .
$$ | . . 2 . . . . . .
$$ | . X . . . . . . .
$$ | O O X X O O . . .
$$ | . X O O X X O . .
$$ | . . O , X . X . .
$$ | . O O X X . . . .
$$ | . O X O O O O . .
$$ | . X X . . . . . .
$$ | . . . . . . . . .[/go]

Re: Re:

Posted: Sat Jul 15, 2017 1:29 pm
by Cassandra
Let's put the cart before the horse ...

(1) White's wishful thinking in the centre.
Click Here To Show Diagram Code
[go]$$W
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$$ | . X . . . . . . .
$$ | . O X X O O 3 . .
$$ | . X O O X X O 2 .
$$ | . . O , X 5 X 1 .
$$ | . O O X X 6 . 4 .
$$ | . O X O O O O . .
$$ | . X X . . . . . .
$$ | . . . . . . . . .[/go]
Click Here To Show Diagram Code
[go]$$W
$$ -------------------
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$$ | . X . . . . . . .
$$ | . O X X O O O . .
$$ | . X O O X X O X .
$$ | . . O , X . X O 8
$$ | . O O X X X 7 X .
$$ | . O X O O O O . .
$$ | . X X . . . . . .
$$ | . . . . . . . . .[/go]
Click Here To Show Diagram Code
[go]$$W
$$ -------------------
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$$ | . X . . . . . . .
$$ | . O X X O O O . .
$$ | . X O O X X O X .
$$ | . . O 9 X . X . X
$$ | . O O X X X O X .
$$ | . O X O O O O . .
$$ | . X X . . . . . .
$$ | . . . . . . . . .[/go]

Re: Tsumego thinking log

Posted: Sat Jul 15, 2017 9:58 pm
by Calvin Clark
On the Maeda problem (Problem 3):
The first thing I notice is that black's shape is bad. It's hard for black to fill the liberty at 'a' because of the weakness at 'b'. The second thing I notice is that there is no obvious way for the white stones to live in the side without capturing something. So the aim is to capture some black stones.
Click Here To Show Diagram Code
[go]$$W White to play
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$$ | . X . . . . . . .
$$ | . O X X O O . . .
$$ | . X O O X X O . .
$$ | . . O a X b X . .
$$ | . O O X X . . . .
$$ | . O X O O O O . .
$$ | . X X . . . . . .
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$$ ------------------[/go]
Ideally, white would like to play :w1:, because of black plays there first, it's hard to contain black. I am very scared of playing such moves in real games because white has so many cutting points, but it seems like this will be needed. So, reading...
Click Here To Show Diagram Code
[go]$$W White tries to contain.
$$ -------------------
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$$ | . . . . . . . . .
$$ | . X . . . . . . .
$$ | . O X X O O 3 . .
$$ | . X O O X X O 2 .
$$ | . . O . X . X 1 5
$$ | . O O X X . 6 4 .
$$ | . O X O O O O . 7
$$ | . X X . . . . . .
$$ | . . . . . . . . .
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$$ | . . . , . . . . .
$$ | . . . . . . . . .
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$$ ------------------[/go]
When I was reading this out, I was unsure about the net at :w7:. (In fact, it does not work, which is left as an exercise for readers.)

I looked for other options for black:
Click Here To Show Diagram Code
[go]$$W Stopping too soon
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$$ | . . . . 6 . . . .
$$ | . X . 7 5 4 . . .
$$ | . O X X O O 2 . .
$$ | . X O O X X O 3 .
$$ | . . O . X . X 1 .
$$ | . O O X X . . . .
$$ | . O X O O O O . .
$$ | . X X . . . . . .
$$ | . . . . . . . . .
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$$ ------------------[/go]
Tragically, I stopped reading at :b7:, thinking the ladder doesn't work for black.

When tried to verify my previous solution the board I noticed that the above ladder does work for black. This is very bad. So I started thinking about ways to break that ladder in sente before playing :w1:
Click Here To Show Diagram Code
[go]$$W Success?
$$ -------------------
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$$ | . . . , . . . . .
$$ | . . . . . . . . .
$$ | . . . 3 6 a . . .
$$ | . X 1 2 4 5 0 . .
$$ | . O X X O O 8 . .
$$ | . X O O X X O 9 .
$$ | . . O . X . X 7 .
$$ | . O O X X . . . .
$$ | . O X O O O O . .
$$ | . X X . . . . . .
$$ | . . . . . . . . .
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$$ ------------------[/go]
After :b10:, white 'a' is atari. So the ladder problem is solved, but would I have seen the correct continuation?

More later...

Re: Re:

Posted: Sat Jul 15, 2017 11:06 pm
by Calvin Clark
@Cassandra:
Click Here To Show Diagram Code
[go]$$W
$$ -------------------
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . , . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . X . . . . . . .
$$ | . O X X O O 3 . .
$$ | . X O O X X O 2 .
$$ | . . O , X 5 X 1 .
$$ | . O O X X 6 . 4 .
$$ | . O X O O O O . .
$$ | . X X . . . . . .
$$ | . . . . . . . . .[/go]
And if :b2: at :w3:?
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