Shapes to remember (SDK level)

gennan · Post by **gennan** » Fri Mar 10, 2023 3:32 am

jlt wrote:Position #78, Black to play. From the same correspondence game against gennan. At move 144 (position below) Katago says White was leading by 1.5. In the end White won by 16.5, increasing his advantage step by step between moves 144 and 286.

During this game, I was aware of what would have been black's optimal endgame in both of those situations, so I knew that black lost points there. I was also aware that white lost points around F9, but only after the fact. A recent comment of mine elsewhere was about situations like these.

Many players up to about my level (3d EGF) are not sufficiently aware how many points can still be gained or lost in the endgame and they just go through the motions of the endgame to "play the game out", sort of assuming that the score is more or less frozen in the endgame, as long as you don't make obvious mistakes. I used to be one of those people and it frustrated me to lose many games to "point-collector" type of players who would catch up to my (perceived) lead during in the endgame to "steal my win".

If you can't beat 'em, join 'em.
This also means that in live games nowadays I spend less time on the opening to save time for the later stages of the middle game and for the endgame.
That's also following advice that InSeong gave me when I was still a member of his online school.

Some other games from that OGS fast correspondence handicap tournament, where my opponent allowed me to catch up in the endgame: https://online-go.com/game/51513875, https://online-go.com/game/51513876

jlt · Post by **jlt** » Fri Mar 17, 2023 2:52 pm

Position #79, White to play an easy endgame move in the upper left quadrant.

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

Answer

Click Here To Show Diagram Code: [go]$$Wc Answer $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . X . X O O . . . . . . . | $$ | . 3 X X X O X . . X X . O O . O O O . | $$ | . . O O O O . . . , . . . X X X X O . | $$ | . 1 . . . O X X . . . X . . . . X X . | $$ | . 2 X . O X O . . . X . . O . X O . . | $$ | . . . . O X X X X . . O X . . . . . . | $$ | . . . X O O O O . . . O X . X . . . . | $$ | . . . . X . . . . . . . O X . X X . . | $$ | . . X O X . O . . , O . O O . O X . . | $$ | . . X X O O . . . . . . . . . O O . . | $$ | . . O O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . X . . X . . . . . |[/go]

The order is important. If White plays

at

then Black can peep:

Click Here To Show Diagram Code: [go]$$Wc Wrong answer $$ --------------------------------------- $$ | . . . 5 . . . . . . . . . . . . . . . | $$ | . . 3 4 6 X . X . X O O . . . . . . . | $$ | . 1 X X X O X . . X X . O O . O O O . | $$ | . 7 O O O O . . . , . . . X X X X O . | $$ | . 2 . . . O X X . . . X . . . . X X . | $$ | . . X . O X O . . . X . . O . X O . . | $$ | . . . . O X X X X . . O X . . . . . . | $$ | . . . X O O O O . . . O X . X . . . . | $$ | . . . . X . . . . . . . O X . X X . . | $$ | . . X O X . O . . , O . O O . O X . . | $$ | . . X X O O . . . . . . . . . O O . . | $$ | . . O O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . X . . X . . . . . |[/go]

Schachus · Post by **Schachus** » Sat Mar 18, 2023 1:33 pm

jlt wrote:Position #79, White to play an easy endgame move in the upper left quadrant.

$$Wc White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . X . X O O . . . . . . . |
$$ | . . X X X O X . . X X . O O . O O O . |
$$ | . . O O O O . . . , . . . X X X X O . |
$$ | . . . . . O X X . . . X . . . . X X . |
$$ | . . X . O X O . . . X . . O . X O . . |
$$ | . . . . O X X X X . . O X . . . . . . |
$$ | . . . X O O O O . . . O X . X . . . . |
$$ | . . . . X . . . . . . . O X . X X . . |
$$ | . . X O X . O . . , O . O O . O X . . |
$$ | . . X X O O . . . . . . . . . O O . . |
$$ | . . O O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . X . . X . . . . . |
$$ | . . O . . . . . . X . . . . . . X . . |
$$ | . . . . . X . O O O X X . . . . X . . |
$$ | . . O O . . . . . , O . . X X X O . . |
$$ | . . X . O X . O . . . . O O X O . O . |
$$ | . . . X X X O . . . . . . . O O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------
Click Here To Show Diagram Code
[go]$$Wc White to play $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . X . X O O . . . . . . . | $$ | . . X X X O X . . X X . O O . O O O . | $$ | . . O O O O . . . , . . . X X X X O . | $$ | . . . . . O X X . . . X . . . . X X . | $$ | . . X . O X O . . . X . . O . X O . . | $$ | . . . . O X X X X . . O X . . . . . . | $$ | . . . X O O O O . . . O X . X . . . . | $$ | . . . . X . . . . . . . O X . X X . . | $$ | . . X O X . O . . , O . O O . O X . . | $$ | . . X X O O . . . . . . . . . O O . . | $$ | . . O O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . X . . X . . . . . | $$ | . . O . . . . . . X . . . . . . X . . | $$ | . . . . . X . O O O X X . . . . X . . | $$ | . . O O . . . . . , O . . X X X O . . | $$ | . . X . O X . O . . . . O O X O . O . | $$ | . . . X X X O . . . . . . . O O O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
Answer
$$Wc Answer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . X . X O O . . . . . . . |
$$ | . 3 X X X O X . . X X . O O . O O O . |
$$ | . . O O O O . . . , . . . X X X X O . |
$$ | . 1 . . . O X X . . . X . . . . X X . |
$$ | . 2 X . O X O . . . X . . O . X O . . |
$$ | . . . . O X X X X . . O X . . . . . . |
$$ | . . . X O O O O . . . O X . X . . . . |
$$ | . . . . X . . . . . . . O X . X X . . |
$$ | . . X O X . O . . , O . O O . O X . . |
$$ | . . X X O O . . . . . . . . . O O . . |
$$ | . . O O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . X . . X . . . . . |
Click Here To Show Diagram Code
[go]$$Wc Answer $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . X . X O O . . . . . . . | $$ | . 3 X X X O X . . X X . O O . O O O . | $$ | . . O O O O . . . , . . . X X X X O . | $$ | . 1 . . . O X X . . . X . . . . X X . | $$ | . 2 X . O X O . . . X . . O . X O . . | $$ | . . . . O X X X X . . O X . . . . . . | $$ | . . . X O O O O . . . O X . X . . . . | $$ | . . . . X . . . . . . . O X . X X . . | $$ | . . X O X . O . . , O . O O . O X . . | $$ | . . X X O O . . . . . . . . . O O . . | $$ | . . O O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . X . . X . . . . . |[/go]
The order is important. If White plays at then Black can peep:
$$Wc Wrong answer
$$ ---------------------------------------
$$ | . . . 5 . . . . . . . . . . . . . . . |
$$ | . . 3 4 6 X . X . X O O . . . . . . . |
$$ | . 1 X X X O X . . X X . O O . O O O . |
$$ | . 7 O O O O . . . , . . . X X X X O . |
$$ | . 2 . . . O X X . . . X . . . . X X . |
$$ | . . X . O X O . . . X . . O . X O . . |
$$ | . . . . O X X X X . . O X . . . . . . |
$$ | . . . X O O O O . . . O X . X . . . . |
$$ | . . . . X . . . . . . . O X . X X . . |
$$ | . . X O X . O . . , O . O O . O X . . |
$$ | . . X X O O . . . . . . . . . O O . . |
$$ | . . O O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . X . . X . . . . . |
Click Here To Show Diagram Code
[go]$$Wc Wrong answer $$ --------------------------------------- $$ | . . . 5 . . . . . . . . . . . . . . . | $$ | . . 3 4 6 X . X . X O O . . . . . . . | $$ | . 1 X X X O X . . X X . O O . O O O . | $$ | . 7 O O O O . . . , . . . X X X X O . | $$ | . 2 . . . O X X . . . X . . . . X X . | $$ | . . X . O X O . . . X . . O . X O . . | $$ | . . . . O X X X X . . O X . . . . . . | $$ | . . . X O O O O . . . O X . X . . . . | $$ | . . . . X . . . . . . . O X . X X . . | $$ | . . X O X . O . . , O . O O . O X . . | $$ | . . X X O O . . . . . . . . . O O . . | $$ | . . O O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . X . . X . . . . . |[/go]

how about

?

That was my first instinct…

jlt · Post by **jlt** » Sun Mar 19, 2023 1:36 am

Your answer is not good either (not better nor worse than the wrong answer described in my previous message). Some precise counting would be necessary but here is one plausible explanation. Let's say that after B16, Black protects with B14. Then White B18 is not sente, and has no sente followup. Whereas in the correct answer B15-B14-B17, the move C18 is White's priviledge.

Note: in the correct answer, after B15-B14, Katago actually wants to play the sente sequence B3-B2-B4-A2 before returning to B17.

kvasir · Post by **kvasir** » Sun Mar 19, 2023 5:08 pm

C13 looks interesting, like I'd want to play there. I think KataGo was quoted above so I could be hallucinating that this a good move.

jlt · Post by **jlt** » Mon Mar 20, 2023 1:13 am

I use 15-block Katago and don't have a GPU, so amateur dan players occasionally find better moves especially in complex fights.

In this situation C13 is a low-policy move but once played, it agrees that it's a good move, about as good as B15. Katago wants to continue locally as follows:

Click Here To Show Diagram Code: [go]$$Wc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . X . X O O . . . . . . . | $$ | . . X X X O X . . X X . O O . O O O . | $$ | . . O O O O . . . , . . . X X X X O . | $$ | . 7 . . . O X X . . . X . . . . X X . | $$ | . 5 X . O X O . . . X . . O . X O . . | $$ | . 6 1 2 O X X X X . . O X . . . . . . | $$ | . . . X O O O O . . . O X . X . . . . | $$ | . 3 . . X . . . . . . . O X . X X . . | $$ | . 4 X O X . O . . , O . O O . O X . . | $$ | . . X X O O . . . . . . . . . O O . . | $$ | . 8 O O . . . . . . . . . . . . . . . | $$ | . 9 . . . . . . . . X . . X . . . . . | $$ | . . O . . . . . . X . . . . . . X . . | $$ | . . . . . X . O O O X X . . . . X . . | $$ | . . O O . . . . . , O . . X X X O . . | $$ | . . X . O X . O . . . . O O X O . O . | $$ | . . . X X X O . . . . . . . O O O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

However this is a bit too complex for me to understand.

jlt · Post by **jlt** » Mon Mar 27, 2023 1:27 am

Position #80, White to play.

Click Here To Show Diagram Code: [go]$$Wc White to play $$ --------------------------------------- $$ | . . . O . . . . . . . . . . . . . . . | $$ | . X O . O . . . . . . . . . O . X . . | $$ | . . X O . . . . . . . . . O . O X . . | $$ | . . X O . . . . . , . . O X . X . . . | $$ | . . X O . . . . . . . . O X . . . . . | $$ | . X O O . . . O . O O O X X . . . . . | $$ | X . X . . . . . . . X X O X . . . . . | $$ | . X . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . X O . O B . . | $$ | . . . . . . . . . . . X X X O X . . . | $$ | . . . . . . . . . . O O X X O . X . . | $$ | . . . . . . . . . . X X O O O O X . . | $$ | . . X . . . . . . . . . . X . . . O . | $$ | . . . , O . . . . , . . . X O O O . . | $$ | . . . O . . . . . . . . . . X X X O . | $$ | . . . . . . . . . . . . . . . . X X O | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

I hesitated between two moves

One of those moves is 4 points better than the other according to Katago. I chose the wrong one because I couldn't see some continuations of the correct answer.

Answer:

The correct answer was hane. I didn't want to play it because I thought that Black could capture the stone like this

Click Here To Show Diagram Code: [go]$$Wc White to play $$ --------------------------------------- $$ | . . . O . . . . . . . . . . . . . . . | $$ | . X O . O . . . . . . . . . O . X . . | $$ | . . X O . . . . . . . . . O . O X . . | $$ | . . X O . . . . . , . . O X . X . . . | $$ | . . X O . . . . . . . . O X . . . . . | $$ | . X O O . . . O . O O O X X . . . . . | $$ | X . X . . . . . . . X X O X . . . . . | $$ | . X . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . 4 6 . | $$ | . . . , . . . . . , . . . . . 2 1 5 . | $$ | . . . . . . . . . . . . X O 3 O X 7 . | $$ | . . . . . . . . . . . X X X O X 8 . . | $$ | . . . . . . . . . . O O X X O . X . . | $$ | . . . . . . . . . . X X O O O O X . . | $$ | . . X . . . . . . . . . . X . . . O . | $$ | . . . , O . . . . , . . . X O O O . . | $$ | . . . O . . . . . . . . . . X X X O . | $$ | . . . . . . . . . . . . . . . . X X O | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

However I couldn't see that the following continuation was very good for White:

Click Here To Show Diagram Code: [go]$$Wcm9 $$ --------------------------------------- $$ | . . . O . . . . . . . . . . . . . . . | $$ | . X O . O . . . . . . . . . O . X . . | $$ | . . X O . . . . . . . . . O . O X . . | $$ | . . X O . . . . . , . . O X . X . . . | $$ | . . X O . . . . . . . . O X . . . . . | $$ | . X O O . . . O . O O O X X . . . . . | $$ | X . X . . . . . . . X X W X . . . . . | $$ | . X . . . . . . . . . . . . . 3 . . . | $$ | . . . . . . . . . . . . . 5 . 1 X X . | $$ | . . . , . . . . . , . . . . 2 X O O . | $$ | . . . . . . . . . . . . X O O O X O . | $$ | . . . . . . . . . . . X X X O X X 4 . | $$ | . . . . . . . . . . O O X X O . X . . | $$ | . . . . . . . . . . X X O O O O X . . | $$ | . . X . . . . . . . . . . X . . . O . | $$ | . . . , O . . . . , . . . X O O O . . | $$ | . . . O . . . . . . . . . . X X X O . | $$ | . . . . . . . . . . . . . . . . X X O | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

(The false geta

doesn't capture

but after Black captures three white stones, White gets good shape and can pull out the marked white stone.)

So Black responds to the hane like this:

Click Here To Show Diagram Code: [go]$$Wc $$ --------------------------------------- $$ | . . . O . . . . . . . . . . . . . . . | $$ | . X O . O . . . . . . . . . O . X . . | $$ | . . X O . . . . . . . . . O . O X . . | $$ | . . X O . . . . . , . . O X . X . . . | $$ | . . X O . . . . . . . . O X . . . . . | $$ | . X O O . . . O . O O O X X . . . . . | $$ | X . X . . . . . . . X X O X . . . . . | $$ | . X . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . 3 4 . | $$ | . . . , . . . . . , . . . . . . 1 2 . | $$ | . . . . . . . . . . . . X O . O X . . | $$ | . . . . . . . . . . . X X X O X . . . | $$ | . . . . . . . . . . O O X X O . X . . | $$ | . . . . . . . . . . X X O O O O X . . | $$ | . . X . . . . . . . . . . X . . . O . | $$ | . . . , O . . . . , . . . X O O O . . | $$ | . . . O . . . . . . . . . . X X X O . | $$ | . . . . . . . . . . . . . . . . X X O | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The fight is still complicated, but this is not the point of this post. I just wanted to remind myself that stones can be sacrificed.

remotecontrol · Post by **remotecontrol** » Mon Mar 27, 2023 5:21 pm

reminds me of this side joseki I had in a game recently.

Click Here To Show Diagram Code: [go]$$Wc Black to play $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . 4 3 . . | $$ | . . . . . . . . . . . . . . . 2 1 . . | $$ | . . . . . . . . . . . . . . . 6 5 . . | $$ | . . . . . . . . . . . . . . . a X b . | $$ | . . . . . . . . . . . . . . . . 7 . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . O . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

jlt · Post by **jlt** » Thu Apr 06, 2023 12:41 am

Position #81, Black to play, find the next 3-4 moves. Nothing complicated, but not on my radar.

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . W . . . . . . . . . . . . | $$ | . . . . . O X . . . . . . . . . . . . | $$ | . . . O O X . . . , . . . . . X . . . | $$ | . O O X X X . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Answer

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . 4 . . . . . . . . . . . . | $$ | . . O . . 1 O . . . . . . . . . . . . | $$ | . . . . 2 O X 3 . . . . . . . . . . . | $$ | . . . O O X . . . , . . . . . X . . . | $$ | . O O X X X . . . . . . . a . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

After that, a simple continuation is Black a. Another possibility is

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . b . . . . . . . . . . . . . | $$ | . . . . . . 4 . . . . . . . . . . . . | $$ | . . O . 5 1 O . . . . . . . . . . . . | $$ | . . . . 2 O X 3 . . . . . . . . . . . | $$ | . . . O O X . . . , c . . . . X . . . | $$ | . O O X X X . . . . . . . . . . . . . | $$ | . 6 X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

after which Black can pull out the two stones at b, or play the extension at c and leave the two stones for the moment. The two stones can be pulled out later, or can be left as aji to be sacrificed later.

EricBackus · Post by **EricBackus** » Thu Apr 06, 2023 10:32 am

jlt wrote:Position #81, Black to play, find the next 3-4 moves. Nothing complicated, but not on my radar.

$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . W . . . . . . . . . . . . |
$$ | . . . . . O X . . . . . . . . . . . . |
$$ | . . . O O X . . . , . . . . . X . . . |
$$ | . O O X X X . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------
Click Here To Show Diagram Code
[go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . W . . . . . . . . . . . . | $$ | . . . . . O X . . . . . . . . . . . . | $$ | . . . O O X . . . , . . . . . X . . . | $$ | . O O X X X . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

What do you think of:

Click Here To Show Diagram Code: [go]$$Wc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . O B . . . . . . . . . . . | $$ | . . . . . O X . . . . . . . . . . . . | $$ | . . . O O X . . . , . . . . . X . . . | $$ | . O O X X X . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

My SDK instinct was to look at this, to try to increase Black's potential territory while decreasing White's. I don't see anything obvious wrong with this, but maybe it's that this ends up in gote rather than sente?

jlt · Post by **jlt** » Thu Apr 06, 2023 12:11 pm

Your move is exactly the one I played in my game so we both have the same wrong intuition, and/or we are both reluctant to cut and leave the cutting stones for later. Let's examine the continuation.

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . 5 . . . . . . . . . . . | $$ | . . O . . 4 O 1 b . . . . . . . . . . | $$ | . . . . . O X 2 d c . . . . . . . . . | $$ | . . . O O X 3 . . , . . . . . X . . . | $$ | . O O X X X . . a . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The differences with the correct answer are that

Black finishes in gote
White has repaired his weakness with
White has played a cutting stone which will become annoying.

After that Katago wants White to start another group at a (the stone

is just a helping stone which will be sacrificed).

If Black had played

at b then besides being slower, White will play c followed with Black d, and it's the stone White c which helps to invade the bottom.

Black could have eliminated the aji of

with

at d but this is even worse since this gives White a free atari at H7.

EricBackus · Post by **EricBackus** » Thu Apr 06, 2023 6:25 pm

jlt wrote:Your move is exactly the one I played in my game so we both have the same wrong intuition, and/or we are both reluctant to cut and leave the cutting stones for later. Let's examine the continuation.

$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . 5 . . . . . . . . . . . |
$$ | . . O . . 4 O 1 b . . . . . . . . . . |
$$ | . . . . . O X 2 d c . . . . . . . . . |
$$ | . . . O O X 3 . . , . . . . . X . . . |
$$ | . O O X X X . . a . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------
Click Here To Show Diagram Code
[go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . 5 . . . . . . . . . . . | $$ | . . O . . 4 O 1 b . . . . . . . . . . | $$ | . . . . . O X 2 d c . . . . . . . . . | $$ | . . . O O X 3 . . , . . . . . X . . . | $$ | . O O X X X . . a . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
The differences with the correct answer are that

Black finishes in gote

White has repaired his weakness with

White has played a cutting stone which will become annoying.
After that Katago wants White to start another group at a (the stone is just a helping stone which will be sacrificed).

If Black had played at b then besides being slower, White will play c followed with Black d, and it's the stone White c which helps to invade the bottom.

Black could have eliminated the aji of with at d but this is even worse since this gives White a free atari at H7.

What you say must be correct.

But I still wonder about

at b. You say White will play c and that will help invade the bottom. But on the other hand, maybe that would be White playing too close to strength?

jlt · Post by **jlt** » Thu Apr 06, 2023 10:57 pm

With

at b, here is a simple continuation. Black protects his corner. White is not alive yet but

will help and may be sacrificed later.

Click Here To Show Diagram Code: [go]$$Bcm5 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . O O X 1 . . . . . . . . . . | $$ | . . . . . O X O 3 2 . . . . . . . . . | $$ | . . . O O X X . . , . . 8 . . X . . . | $$ | . O O X X X . . . 6 . . 4 7 . . . . . | $$ | . . X . . . . . . . . . . 5 . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Another possibility is this

Click Here To Show Diagram Code: [go]$$Bcm5 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . O O X 1 . . . . . . . . . . | $$ | . . . . . O X O 3 2 . . . . . . . . . | $$ | . . . O O X X . . , . . . . . X 0 . . | $$ | . O O X X X . . . 6 5 . 4 . . 9 8 . . | $$ | . . X . . . . . . 7 . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

White gets the corner and

,

and

have played lightly inside Black's sphere of influence. Some of these stones may be sacrificed later.

gennan · Post by **gennan** » Fri Apr 07, 2023 3:11 am

jlt wrote:Position #81, Black to play, find the next 3-4 moves. Nothing complicated, but not on my radar.

$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . W . . . . . . . . . . . . |
$$ | . . . . . O X . . . . . . . . . . . . |
$$ | . . . O O X . . . , . . . . . X . . . |
$$ | . O O X X X . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------
Click Here To Show Diagram Code
[go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . W . . . . . . . . . . . . | $$ | . . . . . O X . . . . . . . . . . . . | $$ | . . . O O X . . . , . . . . . X . . . | $$ | . O O X X X . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
Answer
$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . 4 . . . . . . . . . . . . |
$$ | . . O . . 1 O . . . . . . . . . . . . |
$$ | . . . . 2 O X 3 . . . . . . . . . . . |
$$ | . . . O O X . . . , . . . . . X . . . |
$$ | . O O X X X . . . . . . . a . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------
Click Here To Show Diagram Code
[go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . 4 . . . . . . . . . . . . | $$ | . . O . . 1 O . . . . . . . . . . . . | $$ | . . . . 2 O X 3 . . . . . . . . . . . | $$ | . . . O O X . . . , . . . . . X . . . | $$ | . O O X X X . . . . . . . a . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The hidden answer was actually my first thought, with white losing sente for a somewhat unclear gain in central influence. I'd assume that this isn't good enough for white to give up sente this early in the game, so white shouldn't even hane at F5 at this moment. The game is still in the early opening, so I feel white should have played elsewhere instead, for example approach a black 4-4 corner, 3-3 invade either corner or some other normal opening move.

I wonder how the situation in the lower left before white F5 arose. To me it already looks beneficial for black, not like en even result (joseki). I think white let himself be tricked there.

jlt · Post by **jlt** » Fri Apr 07, 2023 4:01 am

Yes I was surprised that my OGS 3k opponent misplayed that common joseki. The game sequence was

Click Here To Show Diagram Code: [go]$$Bc $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 2 . . . . . . . . . . . . . . . . | $$ | . . . . . a . . . . . . . . . . . . . | $$ | . . . O 6 9 . . . , . . . . . X . . . | $$ | . 8 4 3 7 1 . . . . . . . . . . . . . | $$ | . . 5 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

which was already bad for White since Black got 2 more points than in the usual joseki, and then White continued at "a" instead of tenuki.

Life In 19x19

Shapes to remember (SDK level)

Re: Shapes to remember (SDK level)

Re: Shapes to remember (SDK level)

Re: Shapes to remember (SDK level)

Re: Shapes to remember (SDK level)

Re: Shapes to remember (SDK level)

Re: Shapes to remember (SDK level)

Re: Shapes to remember (SDK level)

Re: Shapes to remember (SDK level)

Re: Shapes to remember (SDK level)

Re: Shapes to remember (SDK level)

Re: Shapes to remember (SDK level)

Re: Shapes to remember (SDK level)

Re: Shapes to remember (SDK level)

Re: Shapes to remember (SDK level)

Re: Shapes to remember (SDK level)