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Shapes to remember (SDK level)

https://lifein19x19.com/viewtopic.php?t=16894

Page 6 of 12

Re: Shapes to remember (SDK level)

Posted: Thu Mar 25, 2021 4:20 pm
by jlt
A no-brainer for today. Somehow I had never thought seriously about that topic before.

Position #46, Black to play.
Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . O O X . . . . . . . . . . . . |
$$ | . . . O X X X . . . . . . . . . . . . |
$$ | . . . O X O . . . . . . . . . . . . . |
$$ | . . . O O X . O . O . X . . . , . . . |
$$ | . . . . . X . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Click Here To Show Diagram Code
[go]$$Bc Answer
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . O O X . . . . . . . . . . . . |
$$ | . . . O X X X . . . . . . . . . . . . |
$$ | . . . O X O . 1 . . . . . . . . . . . |
$$ | . . . O O X . O . O . X . . . , . . . |
$$ | . . . . . X . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
In the game I captured directly following the proverb to capture the laddered stone at the earliest opporunity, but this is less good than the solution. The move above allows White to play a forcing move
Click Here To Show Diagram Code
[go]$$Bc Forcing move
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . O O X . . . . . . . . . . . . |
$$ | . . . O X X X . . . . . . . . . . . . |
$$ | . . . O X O 3 1 . . . . . . . . . . . |
$$ | . . . O O X 2 O . O . X . . . , . . . |
$$ | . . . . . X . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
It's clearly better than playing :b3: directly. Adding moves :b1: and :w2: is good for Black, as :w2: is almost useless while :b1: faces the center and exerts pressure on the white group.

Re: Shapes to remember (SDK level)

Posted: Tue Mar 30, 2021 11:39 am
by jlt
Position #47, White to play.
Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O X . O . . . O X X . . X X O O . . |
$$ | . O X O . O . . . O . X . O . X O . . |
$$ | . O X O . X . . . O . . . X . X O . . |
$$ | . X O O X . . . . . . . . . . X X O . |
$$ | X . X X O O . . . . . O . O O O O O . |
$$ | . X . . X O . . . . . . O X X O X X O |
$$ | . . . . X X . . . . . . O . X X X . O |
$$ | . . . . . . . . . O . X X X . X X O O |
$$ | . . . , . . . . . , O X X O X O X X O |
$$ | . . . . . . . . . . . X O O O O X . X |
$$ | . . . X . . . . . O . . . . . X O X . |
$$ | . . X . O . . . . . . . . . O O O X X |
$$ | . X . . . . . . . . . . . . X . . O . |
$$ | . . . O . . . . . . X . . . . . O . . |
$$ | . . X O . . . O O , . . . . X , . X . |
$$ | . . X O . O O X . . X . . . . X . . . |
$$ | . . . . . . X . X . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Black only has one eye but M7 and T6 are miai so Black can connect to a living group. However White has a good endgame move.
Click Here To Show Diagram Code
[go]$$Wc Answer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O X . O . . . O X X . . X X O O . . |
$$ | . O X O . O . . . O . X . O . X O . . |
$$ | . O X O . X . . . O . . . X . X O . . |
$$ | . X O O X . . . . . . . . . . X X O . |
$$ | X . X X O O . . . . . O . O O O O O . |
$$ | . X . . X O . . . . . . O X X O X X O |
$$ | . . . . X X . . . . . . O . X X X . O |
$$ | . . . . . . . . . O . X X X . X X O O |
$$ | . . . , . . . . . , O X X O X O X X O |
$$ | . . . . . . . . . . . X O O O O X . X |
$$ | . . . X . . . . . O . . . . . X O X . |
$$ | . . X . O . . . . . . . . . O O O X X |
$$ | . X . . . . . . . . . . . . X . . O . |
$$ | . . . O . . . . . . X . . . . . O . . |
$$ | . . X O . . . O O , . . . . X , 1 X . |
$$ | . . X O . O O X . . X . . . . X a b . |
$$ | . . . . . . X . X . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Black can't block at "a":
Click Here To Show Diagram Code
[go]$$Wc Blocking at a
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O X . O . . . O X X . . X X O O . . |
$$ | . O X O . O . . . O . X . O . X O . . |
$$ | . O X O . X . . . O . . . X . X O . . |
$$ | . X O O X . . . . . . . . . . X X O . |
$$ | X . X X O O . . . . . O . O O O O O . |
$$ | . X . . X O . . . . . . O X X O X X O |
$$ | . . . . X X . . . . . . O . X X X . O |
$$ | . . . . . . . . . O . X X X . X X O O |
$$ | . . . , . . . . . , O X X O X O X X O |
$$ | . . . . . . . . . . . X O O O O X . X |
$$ | . . . X . . . . . O . 5 . . . X O X . |
$$ | . . X . O . . . . . . . . . O O O X X |
$$ | . X . . . . . . . . . . . . X . . O c |
$$ | . . . O . . . . . . X . . . . . O e d |
$$ | . . X O . . . O O , . . . . X , 1 X . |
$$ | . . X O . O O X . . X . . . . X 2 3 . |
$$ | . . . . . . X . X . . . . . . . . 4 . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
If Black c White d then Black e would be self-atari so Black is dead. Therefore :b2: was wrong and should have been at "b". Here is a continuation suggested by Katago:
Click Here To Show Diagram Code
[go]$$Wc Stepping back at b
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O X . O . . . O X X . . X X O O . . |
$$ | . O X O . O . . . O . X . O . X O . . |
$$ | . O X O . X . . . O . . . X . X O . . |
$$ | . X O O X . . . . . . . . . . X X O . |
$$ | X . X X O O . . . . . O . O O O O O . |
$$ | . X . . X O . . . . . . O X X O X X O |
$$ | . . . . X X . . . . . . O . X X X . O |
$$ | . . . . . . . . . O . X X X . X X O O |
$$ | . . . , . . . . . , O X X O X O X X O |
$$ | . . . . . . . . . . . X O O O O X . X |
$$ | . . . X . . . . . O . . . . . X O X . |
$$ | . . X . O . . . . . . . . . O O O X X |
$$ | . X . . . . . . . . . . f . X . . O . |
$$ | . . . O . . . . . . X . . . 0 . O . . |
$$ | . . X O . . . O O , . . . 9 X 8 1 X . |
$$ | . . X O . O O X . . X . . . 7 X 3 2 . |
$$ | . . . . . . X . X . . . . . . 5 4 6 . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Next move :w11: is at "f". I can't read the fight but the basic idea is that Black is forced to connect in gote at some point, allowing White to save stones around :w9: or at least to have a good endgame, using the aji of the stones :w5:, :w7: and :w9:. Anyway these three stones are in Black's area so can be sacrificed without damage if necessary.

Re: Shapes to remember (SDK level)

Posted: Mon Apr 05, 2021 2:48 pm
by jlt
Position #48, White to play.
Click Here To Show Diagram Code
[go]$$Bc White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . 1 . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . O O O . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . O . O . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
In the game I was surprised by :b1: but this is actually the "blue move". What I had expected instead of :b1: was
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . 3 X X . 5 . . . . . . . . . . . . . |
$$ | . 1 O O O . . . . , . . . . . X . . . |
$$ | . 2 . . . . . . . . . . . . . . . . . |
$$ | . 4 X . . . . . . . . . . . . . . . . |
$$ | . . 6 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . O . O . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Back to the game. Here is the continuation suggested by Katago, which is apparently not in Josekipedia:
Click Here To Show Diagram Code
[go]$$Bc Answer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . 1 . . . . . . . . . . . . . |
$$ | . 5 X X . . . . . . . . . . . . . . . |
$$ | . 3 O O O . . . . , . . . . . X . . . |
$$ | . 4 . . . . . . . . . . . . . . . . . |
$$ | . 6 X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 2 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . a . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . O . O . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Actually Katago suggests to tenuki at "a" for :b3: but I am showing the local continuation.

But what if :b3: jumps, are the three white stones in trouble?
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . 1 . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . O O O . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . 3 . 5 . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 2 . 4 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]
Click Here To Show Diagram Code
[go]$$Wcm6
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . 4 . . a X 2 . . . . . . . . . . . . |
$$ | 6 3 X X . 1 . . . . . . . . . . . . . |
$$ | . . O O O . . . . , . . . . . X . . . |
$$ | . 5 . . . . . . . . . . . . . . . . . |
$$ | . 7 X . X . X . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]
Black can't play :b11: at :w12: because of the threat at "a".

Re: Shapes to remember (SDK level)

Posted: Mon Apr 05, 2021 6:34 pm
by dhu163
I'm not sure how useful human comments are post AI, but here's a try for coming up with explanations without checking the AI.

48:
From what I've seen, just in the upper left, hane connect is particularly popular for AI when white's pincer stone is at D11. Otherwise, I think katago prefers hane connect normally for closer pincers anyway. The key is to threaten either B14 (directly) or prepare with E14, trying to induce white to press at F16. But :b1: at F18 has also become played after it was found in alphago teach, released in Dec 2017. It was almost not considered at all (or at least discarded/forgotten) pre alphago. These days it is common enough that I might realise it is better in this position (in a 1hr each game) but still rare.
In your position, hane, connect and jump is still a nice way to get sente locally. However, in this position, there are the weak black stones on the left that can only make a one space jump. This feels like to me the main reason not to make white thicker, especially not C10. Furthermore, the F17 jump can be too close to thickness. That is normally exploited with H17.

Your second KG diagram is interesting. The difference to the first KG diagram seems very subtle. I'm not sure how much difference F17-F18 makes. F17 is further from the C15 cut and not so tight on the E16 liberties, but if W had defended tightly at C13, there wasn't much there anyway. As far as I can tell, the D11 peep is useful aji pretty soon after say E9 and so may be C13 or C15 (if C13 response then A15 endgame + cut + C12 is overconcentrated + some D11 aji remains), though they seem far into the future now.

In the first KG diagram, aji definitely remains, but perhaps it takes a move for B to prepare and threaten it? Whereas in the second diagram as long as black has a move around D11 and E14, the C15 cut becomes a problem that threatens to kill something, especially as white doesn't have the F16 forcing move. In addition white never wants to add another move where white is already low and making one space extensions. Of course, white is thicker here and has the right to fight and not let this happen easily, so it is pretty subtle. I anticipate a sequence like Q6-R17 following, but white attack around C8, D8, E9, F9, G6 remain interesting. Perhaps black can play C9 or D9 to more forcefully exploit the two spaces between C10-C13 though. But for the time being perhaps white is ok. If so, locally I'd like to aim for D11 and D13 by first playing E9. As white is thick, I would be nervous about shape attacks such as D9 from white though or E10-F10-F9-D10-E8-D11 when white has the ladder. I'm not strong enough to know what happens here at a glance.
Click Here To Show Diagram Code
[go]$$Bc White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . X X X . . . . . . . . . . . . . . . |
$$ | . X O O O . . . . , . . . . . X . . . |
$$ | . O . . . . . . . . . . . . . . . . . |
$$ | . O X . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . |
$$ | . . . 6 . . . . . . . . . . . . . . . |
$$ | . . O 1 . . . . . , . . . . . , . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . 4 2 3 . . . . . . . . . . . . . . |
$$ | . . . . 5 . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . O . O . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
In your third (hidden) KG diagram, :b3: jumping out is certainly something black wants to aim for (or even B14 in extreme scenarios), but it seems early because C10-C12 can get strength by attacking D8 as well as the aji in your fourth diagram. It can feel like you are fighting against nothing and may be chasing E16 into your upper side potential. I don't understand :w4: if white can't kill black or it is unnecessary for building territory/saving C12. It is saying I am worried about my weakness at D11, and can still connect underneath later, but I'd be worried if :b5: could be played at B17. B17 is a key point for both sides, both big endgame and concerning the connection for both sides. Normally for :b3: locally, black delays making the choice between B16 and G17.
47:
oo. Didn't notice that in the ? seconds I spent. Looks very tricky. The M4 peep looks relevant in some variations because if L5 is cut off, so is the escape route for M9, but white also has cutting points. :w5: at M8 also wasn't my first instinct, instead at M7, but both have lots of bad aji. I'm imagining M8-L9-K9-L8-L7 or M7-L8-L7-K9-?.
46:
hmm, my thought process was
tesuji -> J3 -> yes, seems to work -> no, wait that's too small, why does white care about that? -> black should be attacking not asking for an exchange -> D2 is bad shape -> C3? -> F2 connects C3 but does nothing on other side -> H2 still leaves G5 -> nothing interesting with F8 because G5 is too damaging -> damn, have to connect -> H5 -> but white at J5 is painful -> but oo I still have J3 to annoy white -> ok H5.

I guess the point here is that black has enough liberties with F3 and G6 (though its close) that all that matters is capturing F5. H5 is the most efficient method. If black was low on liberties then G5 is better. If black is low on eyespace then G4 is better.

The reason I would give for a more efficient move to exist locally is that black already has 4 stones trying to capture F5, namely E5, F6, G6 (I would label E6 and F3 as connecting moves, that increase black's liberties instead, and G7 as too far away). Normally 4 stones is enough to capture one stone, so you don't need to add another one at G5. Of course, G6 only blocks F5 escaping in say 60% of local variations and H4 threatens it, but you don't need to play G5 until white threatens to save F5 in those 40% of variations (i.e. when white plays G4). Instead you can block what H4 is threatening. Not sure how easy it is to apply such a principle though.
45:
thought process (not so linearly this time):
white G14 doesn't cut -> upper right looks solid though P14 isn't small -> the N10 group isn't 100% but ok especially with G14 aji -> what is happening at D10? -> ooh black J2 looks scary -> what is N3 doing left there! -> defense at N3 still seems risky with shortage of liberties -> is there a G1 tesuji? -> no white wins by one liberty -> read answer

Having read answer, it makes sense, but I think I might well have responded at a too in a game if I didn't have enough time to read that the black group was weak enough. The difference between one eye and two is big. I see that :w9: also defends against my worries of J2.

It is very cute that as white has J9 in sente, black E10 is no longer sente, making white D9 a threat in combination with the B11 hane. Exact move order I don't know but imagine after e-f exchange, D9-D10-B11-B10(?)-E10-C10-B9-A10-C9. White wins by one liberty. Another aji to read is D9-B10-E10-D7-B9-B8-D10-A9-B11 but as E10 is still valuable, I think D9-E10 is fairly likely.

Perhaps you prioritised safety for white's groups too much, but I think it is fairly normal in this situation.
44:
Thought process:
G8 interesting -> probably captured -> hmm no H7 is short on libs -> but still captured -> everything else seems connected and alive -> G5? -> still no -> F14 -> G13 is a cut -> E14 needed first -> is E12 a tesuji? -> needs reading -> R2 annoying ko -> O15 annoying but might not work given O12 -> oh wait is it just C9 -> how did I miss that? -> is black even not alive at top? -> hmm, I think black is only ko for life -> not sure then.
43:
lots of reading at F8 -> looks close to creating something but can't capture anything and G10 doomed -> ?? -> read answer
ah, it is easy to forget that N12 is alive. Still it's difficult to find the right sequence even when you know you have to attack that black group. In the final position white's group seems pretty vulnerable, but I couldn't see a way to attack severely. J19 is the standard tesuji; if B starts at G18, I think white can even block at H18 and be alive, but K19 may well still be better; if B starts at K19, white has enough liberties to even consider G17. Note that white always threatens to cut at L16 as white hasn't played N15 to short their own liberties. Black doesn't even seem to have any eyes yet, so needs to attack the group at the top accurately. That's pretty complicated.
42:
Once I see white's threat I see. Misread explanation of third diagram as "White should even connect the stone in atari" -> what?? white is on the verge of death -> oh I misread.
37:
I think :b1: can consider playing at K3 to avoid the white's O2 life making tesuji. My ideal sequence is
Click Here To Show Diagram Code
[go]$$Bc answer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . X O . O O . . |
$$ | . . X , X . . . . , . X . X . X X . . |
$$ | . . . . . . . . . . . . X X . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . , . . . . . , . . . . . , X . . |
$$ | . X O O . . . . O O O . . . . . . X . |
$$ | X . X . O . . . X X O X . . X X X O . |
$$ | . X . . . O . . X O X X O . O X O . O |
$$ | . . . X . . . O O O . . O . O O . O . |
$$ | . . X . . . . . X X X X X X O . O . . |
$$ | . . X O . O X . X O O O X . X O O . . |
$$ | . O O . . O . X O 1 8 7 O 5 X . . . . |
$$ | . . . . . . 6 X O 2 O 4 3 . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
:b2: at L3 is ko for life. But it isn't trivial for black to fight either as white is so thick.
However, looking at this diagram compared to KG's variation, KG's variation seems better both for endgame and life as P2 is a valuable move to prevent S2. The only thing my diagram gains is to reduce white by around 2 points. Furthermore, :w2: is probably better at J1. Although :w2: is a tesuji, black is happy to force white into it because black gains by answer everything. I was too aggressive in my variation.

Re: Shapes to remember (SDK level)

Posted: Mon Apr 05, 2021 11:54 pm
by jlt
Thank you for your comments, I will read them in more detail tonight (no time right now), but to answer to
I'm not sure how useful human comments are post AI
Yes, I am very interested in human comments, whether coming from stronger players like you or from weaker players who have been silent so far. An AI can only show the main lines and answer my questions, but cannot think about all the variations that might be played in a game between humans.

Re: Shapes to remember (SDK level)

Posted: Wed Apr 07, 2021 2:10 pm
by jlt
Further Katago variations on my third hidden diagram.
Suppose that Black plays :b5: at B17, then Katago thinks the only move for :w6: is B16.
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . 1 . . . . . . . . . . . . . |
$$ | . 5 X X . . . . . . . . . . . . . . . |
$$ | . 6 O O O . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . 3 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 2 . 4 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]
Click Here To Show Diagram Code
[go]$$Bcm7 :w14: at a or b
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . X X X . . 2 . . . . . . . . . . . . |
$$ | . O O O O . . . . , . . . . . X . . . |
$$ | . . . . . . a . . . . . . . . . . . . |
$$ | . . X . X . b . . . . . . . . . . . . |
$$ | . . . 1 . . . . . . . . . . . . . . . |
$$ | . . O 3 O . . . . . . . . . . . . . . |
$$ | . . . 4 5 7 . . . . . . . . . . . . . |
$$ | . . O , 6 . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]
Instead of peeping, Black may want to continue jumping.
Click Here To Show Diagram Code
[go]$$Bcm7 Running fight
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X 5 . . . . . . . . . . . . |
$$ | . X X X . . 2 . . . . . . . . . . . . |
$$ | . O O O O . . 4 . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . a X . X . 1 . . . . . . . . . . . . |
$$ | . . . 3 . . . . . . . . . . . . . . . |
$$ | . . O . O . . . . . . . . . . . . . . |
$$ | . . . . . . 6 . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]
In the above diagram, White may want to connect underneath at "a" for :w8:, this is slightly less good.

In any case, Black cannot push and cut
Click Here To Show Diagram Code
[go]$$Bcm7 bad for Black
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . X X X . 3 2 . . . . . . . . . . . . |
$$ | . O O O O 4 5 7 9 , . . . . . X . . . |
$$ | . . . . . . 6 8 . . . . . . . . . . . |
$$ | . a X . X . 1 . . . . . . . . . . . . |
$$ | . . . . . . 0 . . . . . . . . . . . . |
$$ | . . O . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]
White can save the 5 stones with "a" at any time.
Edit: last diagram corrected.

Re: Shapes to remember (SDK level)

Posted: Thu May 13, 2021 2:53 pm
by jlt
Really a shape problem.

Position #49, White to play. What is White's next move, and what is the continuation?
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X X O |
$$ | . . X O . . . . . . X X . X . O X O . |
$$ | . . X O . . . . . , . O . X . X O O O |
$$ | . . . O . . . . . . O . O X . X X O . |
$$ | . X . . . . . . . . O O X X X O O O . |
$$ | . . . . . . . . . . . X O O O X X . . |
$$ | . . . . . . . . . . . X . . . O X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . O O O . . . , . . . . X , . . . |
$$ | . . O X O X X . . . . . . . . X . . . |
$$ | . . X X X . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Answer:
Click Here To Show Diagram Code
[go]$$Wc Katago's answer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X X O |
$$ | . . X O . . . . . . X X . X . O X O . |
$$ | . . X O . . . . . , . O . X . X O O O |
$$ | . . . O . . . . . . O . O X . X X O . |
$$ | . X . . . . . . . . O O X X X O O O . |
$$ | . . . . . . . . . . . X O O O X X . . |
$$ | . . . . . . . . . . b X . . . O X . . |
$$ | . . . . . . . . . . . 3 . 1 . 2 . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . a . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . O O O . . . , . . . . X , . . . |
$$ | . . O X O X X . . . . . . . . X . . . |
$$ | . . X X X . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
White cannot kill the three stones, at least not immediately. :w3: strengthens the three white stones so that White can aim at attacking one of the black groups later. For instance if Black doesn't defend the group on the right, then "a" will be a good point for White. If Black doesn't defend the two stones then "b" will be a good point for White.

Re: Shapes to remember (SDK level)

Posted: Fri May 14, 2021 6:48 am
by Bill Spight
Edit: Nevermind. :D

I assume that the following is the correct diagram for the last one in #81..
Click Here To Show Diagram Code
[go]$$Bcm7 bad for Black
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . X X X . 3 2 . . . . . . . . . . . . |
$$ | . O O O O 4 5 7 9 , . . . . . X . . . |
$$ | . . . . . . 6 8 . . . . . . . . . . . |
$$ | . a X . X . 1 . . . . . . . . . . . . |
$$ | . . . . . . 0 . . . . . . . . . . . . |
$$ | . . O . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]
White can save the 5 stones with "a" at any time.

Re: Shapes to remember (SDK level)

Posted: Fri May 14, 2021 7:33 am
by jlt
Yes indeed, there were two :w12: in the diagram, I forgot to erase one. I edited my post according to your comment.

Re: Shapes to remember (SDK level)

Posted: Fri Jun 11, 2021 3:40 am
by jlt
Position #50, White to play. Shouldn't be hard but I missed it.
Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . O . X X X X X . O . . . . |
$$ | . . . O X . O X X O O O . X O . . . . |
$$ | . . O , O . . O O , . . . X . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . O . |
$$ | . . X . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . X . O . . . . . , . . . . . , O X . |
$$ | . X O . . . . . . . . . . . . . . X . |
$$ | X . X O . . . . . . . . . . . O O O X |
$$ | . X . . . . . . . X X . X O . O X X . |
$$ | X O O O . O . . O X O X . X O X X . . |
$$ | . X X . . . O O X O O O X . O O X . . |
$$ | . . . X X X O X X X . . X X O X . . . |
$$ | . . O X O O X . X . O O . . X X . . . |
$$ | . O . O O O X . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Answer:
Click Here To Show Diagram Code
[go]$$Wc Answer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . O . X X X X X . O . . . . |
$$ | . . . O X . O X X O O O . X O . . . . |
$$ | . . O , O . . O O , . . . X . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . O . |
$$ | . . X . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . X . O . . . . . , . . . . . , O X . |
$$ | . X O . . . . . . . . . . . . . . X . |
$$ | X . X O . . . . . . . . . . . O O O X |
$$ | . X . . . . . . . X X . X O . O X X . |
$$ | X O O O . O . . O X O X . X O X X . . |
$$ | . X X . . . O O X O O O X . O O X . . |
$$ | . . . X X X O X X X . . X X O X . . . |
$$ | . . O X O O X . X . O O . . X X . . . |
$$ | . O . O O O X . 2 1 . . . 3 . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Re: Shapes to remember (SDK level)

Posted: Fri Jun 11, 2021 10:56 pm
by jlt
Yet another simple move.

Position #51, White to play. There are several possible good moves, the question is how to attack/put pressure on the group K16.
Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . O . |
$$ | . . . . . . . . . . . X . . . . . . O |
$$ | . . . O . . O . . X . . . O . O O O X |
$$ | . . . . . . . . . . . . . . . . X X X |
$$ | . . . . . . O . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . O O . . |
$$ | . O . . . . . . . . . . . . . . X X . |
$$ | O . O . . . . . . . . . . . . X . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . X O X . . . . . , O . . . . X . . . |
$$ | . X O X . . . . . . . O O O . . . . . |
$$ | . X O . . . . . . . . . X X X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Answer:
In fact, many good moves are available on the board:
Click Here To Show Diagram Code
[go]$$Wc Possible moves
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . O . |
$$ | . . . . . . . b a . . X . . . . . . O |
$$ | . . . O . . O . . X . . . O . O O O X |
$$ | . . d . . . . . . . . . . . . . X X X |
$$ | . . e . . . O . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . c . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . O O . . |
$$ | . O . . . . . . . . . . . . . . X X . |
$$ | O . O f . . . . . . . . . . . X . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . X O X . . . . . , O . . . . X . . . |
$$ | . X O X . . . . . . . O O O . . . . . |
$$ | . X O . . . . . . . . . X X X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
I am mostly interested in move "a" which attacks Black's shape. Katago expects Black to just answer and then White takes a big point elsewhere.
Click Here To Show Diagram Code
[go]$$Wc continuation of move a
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . O . |
$$ | . . . . . . . . 1 2 . X . . . . . . O |
$$ | . . . O . . O . . X . . . O . O O O X |
$$ | . . . . . . . . . . . . . . . . X X X |
$$ | . . 3 . . . O . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . O O . . |
$$ | . O . . . . . . . . . . . . . . X X . |
$$ | O . O . . . . . . . . . . . . X . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . X O X . . . . . , O . . . . X . . . |
$$ | . X O X . . . . . . . O O O . . . . . |
$$ | . X O . . . . . . . . . X X X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
For move :w3:, White shouldn't make a move around N17: the upper right corner doesn't need to be protected since it is completely alive (for instance, a black move at O18 wouldn't be sente), and since Black has strenghthened his group with :b2:, a white move around N17 won't put a lot of pressure so Black won't respond.

Black can't play :b2: at O18, otherwise we get the following sequence:
Click Here To Show Diagram Code
[go]$$Wc continuation of move a (2)
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . 7 8 6 2 . . . O . |
$$ | . . . . . . . . 1 . 9 X 3 5 . . . . O |
$$ | . . . O . . O . . X 0 b 4 O . O O O X |
$$ | . . . . . . . . . . . . a . . . X X X |
$$ | . . . . . . O . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . c . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . O O . . |
$$ | . O . . . . . . . . . . . . . . X X . |
$$ | O . O . . . . . . . . . . . . X . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . X O X . . . . . , O . . . . X . . . |
$$ | . X O X . . . . . . . O O O . . . . . |
$$ | . X O . . . . . . . . . X X X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
and then White a, Black b, White c follow.

Re: Shapes to remember (SDK level)

Posted: Fri Jul 23, 2021 12:59 am
by jlt
Position #52, from an OGS 1k vs. 2k game. Black to play an endgame move.
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . O . . . . . . |
$$ | . . . O X . . . . . . O . O X . . . . |
$$ | . . O X X . . X . O . O . O O X . . . |
$$ | . . O , . . X . . , . X O X X X . . . |
$$ | . . . O . . . O O . O O O X . . . . . |
$$ | . . . . . X X X O . . X X . . . . . . |
$$ | . . . X O . X O . . . . . . . . . . . |
$$ | . . . O . O X O . . O O X . . . . . . |
$$ | . . . . O . X O . O X . X . . . . . . |
$$ | . . . , . . X X . O X . . X . , X . . |
$$ | . . . . O . . . . O . . . . . . . . . |
$$ | . O O . . . . X . O X X . O . . O . . |
$$ | . X O . . . . . X X O . X X O . . . . |
$$ | . X O . X . X X O . O . X O . O . . . |
$$ | . X O O . X X O O . . . . . O O O . . |
$$ | . . X O O O X X O , O O O O X O X X . |
$$ | . . X O . . O O X X X X X X X X . . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Katago's answer:
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . O . . . . . . |
$$ | . . . O X . . . . . . O . O X . . . . |
$$ | . . O X X . . X . O . O . O O X . . . |
$$ | . . O , . . X . . , . X O X X X . . . |
$$ | . . . O . . . O O . O O O X . . . . . |
$$ | . . . . . X X X O . . X X . . . . . . |
$$ | . . . X O . X O . . . . . . . . . . . |
$$ | . . . O . O X O . . O O X . . . . . . |
$$ | . . . . O . X O . O X . X . . . . . . |
$$ | . . . , . . X X . O X . . X . , X . . |
$$ | . . . . O . . . . O . . . . a . 1 . . |
$$ | . O O . . . . X . O X X . O . 2 O . . |
$$ | . X O . . . . . X X O . X X O . . . . |
$$ | . X O . X . X X O . O . X O . O . . . |
$$ | . X O O . X X O O . . . . . O O O . . |
$$ | . . X O O O X X O , O O O O X O X X . |
$$ | . . X O . . O O X X X X X X X X . . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
White is not alive yet so :b1: is sente. After :w2:, Black aims at a.

If Black doesn't play at :b1: then a sequence like this can happen:
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . 3 . . . . . . . . O . . . . . . |
$$ | . 2 1 O X . . . . . . O . O X . . . . |
$$ | . . O X X . . X . O . O . O O X . . . |
$$ | . . O , . . X . . , . X O X X X . . . |
$$ | . . . O . . . O O . O O O X . . . . . |
$$ | . . . . . X X X O . . X X . . . . . . |
$$ | . . . X O . X O . . . . . . . . . . . |
$$ | . . . O . O X O . . O O X . . . . . . |
$$ | . . . . O . X O . O X . X . . . 5 . . |
$$ | . . . , . . X X . O X . . X . 4 X . . |
$$ | . . . . O . . . . O . . . . . . . . . |
$$ | . O O . . . . X . O X X . O . . O . . |
$$ | . X O . . . . . X X O . X X O . . . . |
$$ | . X O . X . X X O . O . X O . O . . . |
$$ | . X O O . X X O O . . . . . O O O . . |
$$ | . . X O O O X X O , O O O O X O X X . |
$$ | . . X O . . O O X X X X X X X X . . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Re: Shapes to remember (SDK level)

Posted: Sat Jul 24, 2021 1:52 am
by jlt
Position #53, White to play.
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X X . X . . . . . . . . . . . . |
$$ | . . . , O O . . . , . . . . . X . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Two moves are possible:
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X X . X . . . . . . . . . . . . |
$$ | . . . , O O . . . , . . . . . X . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . O a . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X b . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
The cut isn't a problem:
Click Here To Show Diagram Code
[go]$$Wc Very good for White
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X X . X . . . . . . . . . . . . |
$$ | . . . , O O . . . , . . . . . X . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . 6 O X . . . . . . . . . . . . . . . |
$$ | . 4 2 O 1 . . . . . . . . . . . . . . |
$$ | . 5 3 . . . . . . . . . . . . . . . . |
$$ | . . X 7 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
So Black would rather play from the other group:
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X X . X . . . . . . . . . . . . |
$$ | . . . , O O . . . , . . . . . X . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 2 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . O 1 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X 3 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
However if Black decides to jump then White can protect the cut:
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X X . X . . . . . . . . . . . . |
$$ | . . . , O O . . . , . . . . . X . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . O 1 . . . . . . . . . . . . . . |
$$ | . . 3 . . . . . . . . . . . . . . . . |
$$ | . . X . 2 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Re: Shapes to remember (SDK level)

Posted: Wed Aug 04, 2021 12:26 am
by jlt
Position #54, Black to play. Several good moves are possible, find a good move in the bottom part of the board.
Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . X , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O O . . . . . . . . . . X . O . . |
$$ | . . X O . . . . . . X . . X O O . . . |
$$ | . . X O . . . . . O X . X . X . . . . |
$$ | . . X O . O . . O X O O . X X , O O . |
$$ | . X . X O . . . O X . . . . . X X O . |
$$ | . . . X O . . . O X . O . . . . . X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . b O . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . X , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O O . . . . a . . . . . X . O . . |
$$ | . . X O . . . . . c X . . X O O . . . |
$$ | . . X O . . . . . O X . X . X . . . . |
$$ | . . X O . O . . O B O O . X X , O O . |
$$ | . X . X O . . . O B . . . . . X X O . |
$$ | . . . X O . . . O B . O . . . . . X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Black needs to find a good way to use the dead marked stones. In the game I played "b", which loses 2.5 points according to Katago. The move "a" is better since it expands further towards the center. The move "b" is about as good as "a".

Re: Shapes to remember (SDK level)

Posted: Sun Aug 15, 2021 2:55 am
by jlt
Position #55:
Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . O O X |
$$ | . . . X . . . . . . . . . O O O O X . |
$$ | . . O . . X . . X . . . . O . O X X X |
$$ | . . . O . . . . . , O O O . . , O X . |
$$ | . . . . . . . . . . O . . . . O X X X |
$$ | . . O . . . . . . X X O O . . O O O X |
$$ | . . . . . . . . . X O O O O . . . O O |
$$ | . . . . . . . . . . X O O . . O O O . |
$$ | . . . . . . . . . . X . O O O O O O X |
$$ | . . . , . . . . . , . X X O O X X O X |
$$ | . . O . . . . . X . . . O O X . X X . |
$$ | . . . . . . X . O X . . X X . X . . . |
$$ | . . . . . X . . O . X . . . . . . . . |
$$ | . O . O . . . . . . . X . . . . . . . |
$$ | . O X O . X . O O . O . . X . X . . . |
$$ | . X O O . . X X . , O X X O X , . . . |
$$ | X . X O . O . . X . O X O O O X . . . |
$$ | . X X X O . . O X X O O O O X . X . . |
$$ | . . . . . . . . . . . . . X . X . . . |
$$ ---------------------------------------[/go]
All times are UTC-07:00
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