Shapes to remember (SDK level)

jlt · **#101**

Position #61, Balck to play. Again a rather basic shape.

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

Knotwilg · **#102**

Hane at the head of two, I assume. BTW before counting the stones I assumed from the shape it was White's turn to play and I would also play there.

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

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

jlt · **#103**

Correct!

jlt · **#104**

Position #62, Black to play. White just played this move:

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

Black has at least two good responses. In the game I played

which is approved by Katago, but I didn't get the continuation right. So how should Black continue after this?

Possible answer:

Katago considers only one move:

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

This moves threatens the hane "a", so White will have to defend. Before playing "d", White can play at "b" or "c". Let's for instance examine "b".

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

Click Here To Show Diagram Code: [go]$$Bcm11 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . O O O . . | $$ | . . . . . . . . . . . . . O X O X X . | $$ | . . . O . O . . . , . . . . X X . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . X X . . . . . . . . . . . . X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . X X . O . . . . . . . . . . . . . . | $$ | . O X X O . . . . . . . . . . . . . . | $$ | . O O O X X . . . , . . . . . , . . . | $$ | . . . . O X . . . . . . . . . . . . . | $$ | . . B O . . . . . . . . . . . . . . . | $$ | . . 2 . 1 . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . O O . . | $$ | . . X X . . . . . . . . . . . O X . . | $$ | . . O , O . . . . , . . . . . , X . . | $$ | . . . O . . . . . . . . . X . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The idea being to sacrifice the marked stone, enclose White in sente and get the influence. Black is cut into two pieces but can manage the fight.

jlt · **#105**

Position #63, White to play in the lower left quadrant. At least two good moves are possible.

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

Knotwilg · **#106**

On 62 I got it right. In a game I might play the outside hane but as a problem I can see why inward is making better use of the two stones above.

On 63

jlt · **#107**

For #63, Knotwilg got one of the good answers. Further remark on that move:

I did consider the move but failed to see its usefulness since it didn't enclose White, and moreover the knight's move can be cut. However Katago doesn't care about the cut, both players get two weak groups so the fight is fair.

Click Here To Show Diagram Code: [go]$$Wc knight's move, what if Black cuts? $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . X . . . . . | $$ | . . . O . . . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , X . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . O . O . O . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . 0 . . . . . . . . . . . | $$ | . . X . . . . . 1 . . . . . . O O . . | $$ | . . . , X X X 2 3 , . . . . . , X . . | $$ | . . 7 O O 4 O O 6 . . . . X . X . . . | $$ | . . . . . 5 . 9 8 . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

So Black won't cut at least for the moment. A simple continuation (there are more complicated variations):

Click Here To Show Diagram Code: [go]$$Wc knight's move, simple continuation $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . X . . . . . | $$ | . . . O . . . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , X . . . . , . . . . . , . . . | $$ | . . . . . . 7 5 . . . . . . . O . . . | $$ | . . O . O . O 4 6 . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . 2 . . . . . . . . . . . | $$ | . . X . . . . . 1 . . . . . . O O . . | $$ | . . . , X X X . . , . . . . . , X . . | $$ | . . 3 O O . O O . . . . . X . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The idea is that :w1:

threatens to enclose Black, so Black gets out with :b2:

and then

defends the white group while weakening Black, so both players get a weak group and the fight is fair.

The other move considered by Katago is this:

jlt · **#108**

Position #64, Black to play. The AI move is not fancy but seemed counter-intuitive to me.

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

Answer:

jlt · **#109**

Position #65, White to play the best endgame move on the top of the board. Provide at least 3-move sequence (nothing fancy).

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

Knotwilg · **#110**

The tesuji that comes to mind is this one

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

I'm playing this out to have a reference. Probably 3 pts better than:

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

Not really sente either

jlt · **#111**

Interesting but :w5:

is not considered as sente by Katago. If I didn't make a calculation mistake, the miai value of :b6:

is only about 2.79167 points, that's too small at this stage of the game. So instead of :w1:

, White can play a much simpler sente move elsewhere. (Nothing difficult, the main point is to notice that the move is sente.)

Knotwilg · **#112**

I must admit it didn't "feel" like sente either.
So maybe my first idea was my best idea after all.

jlt · **#113**

That's closer but there is a better move:

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

Black may atari after that but still has to add a defensive move.

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

If Black plays :b6:

elsewhere, White has a ko for the life of the black group.

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

So after Black's defensive move, White can play elsewhere. A simple local continuation is the monkey jump:

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

ez4u · **#114**

Knotwilg wrote:

I must admit it didn't "feel" like sente either.
So maybe my first idea was my best idea after all...

I think you need to flip your idea.

jlt · **#115**

Position #66, White to play.

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

Knotwilg · **#116**

This is not an easy problem, while the answer is probably very clear.

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

The first move that comes to mind is hane at the head of two. After this relatively calm sequence I'd like to take sente and play A, rather than defend against the cut at B by playing C first. Forcing at D is another option.

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

How about this trade?

Click Here To Show Diagram Code: [go]$$Wc White to play $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . a . . . . . . . . . . . | $$ | . . . O O X . . . . . . . . . X X . . | $$ | . . O , X X . . . X . . . X . O X . . | $$ | . . . . . . . . . . . . . . . O O . . | $$ | . . O . . . . . . . . . . . . . 3 1 . | $$ | . . . . . . . . . . . . . . 4 2 O X . | $$ | . . . O O . . . . . . . . . . O X 0 . | $$ | . . O X . . . . . . . . . . . O B . . | $$ | . . . X . . . . . , . . . . . b 5 6 . | $$ | . . X . . . . . . . . . . . . . 7 8 . | $$ | . . . . . . . . . . . . . . . . 9 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . X , O . . . . , . d . . . O . . . | $$ | . . . X O . . O . . X . . X . . O . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

This hane is the second thought.
:b4:

looks unreasonable, so

Click Here To Show Diagram Code: [go]$$Wc White to play $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . a . . . . . . . . . . . | $$ | . . . O O X . . . . . . . . . X X . . | $$ | . . O , X X . . . X . . . X . O X . . | $$ | . . . . . . . . . . . . . . . O O . . | $$ | . . O . . . . . . . . . . . . . . 1 . | $$ | . . . . . . . . . . . . . . . . O X . | $$ | . . . O O . . . . . . . . . . O X . . | $$ | . . O X . . . . . . . . . . . O B . . | $$ | . . . X . . . . . , . . . . 3 2 . . . | $$ | . . X . . . . . . . . . . . . 4 . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . X , O . . . . , . d . . . O . . . | $$ | . . . X O . . O . . X . . X . . O . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

jlt · **#117**

Thanks for your comments,

First, Katago's local answer. The AI sees two main local variations, with only one move for :w1:

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

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

Note that Black can't play :b4:

at

, otherwise the following sequence is bad for Black (I couldn't see the variation during the game, which is why I rejected :w1:

).

Click Here To Show Diagram Code: [go]$$Wc is bad for Black $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O O X . . . . . . . . . X X . . | $$ | . . O , X X . . . X . . . X . O X . . | $$ | . . . . . . . . . . . . . . . O O 2 . | $$ | . . O . . . . . . . . . . . . . . 5 b | $$ | . . . . . . . . . . . . . . . 1 O X . | $$ | . . . O O . . . . . . . . . . O X a . | $$ | . . O X . . . . . . . . . . . O X . . | $$ | . . . X . . . . . , . . . . . , 3 4 . | $$ | . . X . . . . . . . . . . . . . c . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

White has a double atari at "a". Black can atari at "c" but afterwards has to choose between protecting "a", or play "b" to capture :w5:

and let White capture 2 stones.

Instead of the above :b2:

, Black may prefer to jump:

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

In any case, Black can't at the same time link to the upper group and separate the two white groups.

That said, Knotwilg's first instinct (R10) is almost as good (less than 1 point difference):

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

Knotwilg's second proposition (S14) is also about 1 point worse than Katago's answer:

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

Knotwilg · **#118**

Interesting. Of course the solution move crossed my mind as well but I dismissed it without further reading because I thought it would anyhow be the wrong order of moves and sort of slow.

My main line is not so different from the 2nd solution and the answer to the question I had is: yes White takes gote in order to ensure the connection. Which is a heuristic surprise, as slow connections are to be avoided and sente matters a lot, as per my Mistakes series.

jlt · **#119**

The move S10 connects R10 with Q11, and at the same time links with the bottom right group while making points, so I guess it's more than a slow connection (two slow moves combined in one may become an efficient move).

jlt · **#120**

Position #67, Black to play. The shape is not yet natural to me.

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

Shapes to remember (SDK level)

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