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 Post subject: Opening problems for AI: Problem 46
Post #1 Posted: Tue Aug 18, 2020 9:37 am 
Honinbo

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White to play.

As always, assume komi. :)

Click Here To Show Diagram Code
[go]$$Bc White to play.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 4 . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , 1 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . a . . . . . . . . . . . . . . . . |
$$ | . . 6 9 3 . . . . , . . . . . , 2 . . |
$$ | . . 7 . . . 8 . . . . b . . 5 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Which is better, the extension to a or the pincer at b?

Enjoy! :D

_________________
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At some point, doesn't thinking have to go on?
— Winona Adkins

My two main guides in life:
My mother and my wife. :)

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 Post subject: Re: Opening problems for AI: Problem 46
Post #2 Posted: Tue Aug 18, 2020 10:41 am 
Tengen
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IMHO, 'a' is the better move

Click Here To Show Diagram Code
[go]$$Bc White to play.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 4 . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , 1 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . a . . . . . . . . . . . . . . . . |
$$ | . . 6 9 3 . . . . , . . . . . , 2 . . |
$$ | . . 7 . . . 8 . . . . b . . 5 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


The position of :w8: makes the difference.

Id :w6: is captured, then :w8: is merely a nusiance. It can mostly be ignored by black, and very possibly be swallowed on a large scale without touching it.
If :w6: lives, then :w8: is the stepping stone for a white attack.




With a white stone at G3, white's play at C5 is sente, threatening B3.

Click Here To Show Diagram Code
[go]$$Wc The expansive defense, allowing white 3 to undercut in sente
$$ | . . . . . . . . . . . . . . . , . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . . O X X . . . . , . . . . . , O . . |
$$ | . 2 X . . . W . . . . b . . X . . . . |
$$ | . . . . 3 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]



Click Here To Show Diagram Code
[go]$$Wc The tight defense, white extends. Black is small and ugly.
$$ | . . . . . . . . . . . . . . . , . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 3 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . . O X X . . . . , . . . . . , O . . |
$$ | . . X . . . W . . . . b . . X . . . . |
$$ | . . . 2 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


This post by Joaz Banbeck was liked by: Bill Spight
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 Post subject: Re: Opening problems for AI: Problem 46
Post #3 Posted: Tue Aug 18, 2020 1:50 pm 
Lives in sente
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I started with more or less the same idea than Joaz: White's pincer at G8 would be pointless if Black can capture C4. However I am wondering about the followup.

Click Here To Show Diagram Code
[go]$$Wc White saves C4
$$ | . . . . . . . . . . . . . . . , . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 3 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 7 . . |
$$ | . . . . . . . . . . . . . . . 6 . . . |
$$ | . . 1 . . . . . . . . . . . . 4 5 . . |
$$ | . . O X X . . . . , . . . . . , O . . |
$$ | . . X . . . W . . 8 . . . . X . . . . |
$$ | . . . 2 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Black's position doesn't look bad, since the marked white stone is under attack, and Black has no weak group.

In comparison, if White had played "b" and let Black capture C4,

Click Here To Show Diagram Code
[go]$$Wc White plays "b"
$$ | . . . . . . . . . . . . . . . , . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 7 . . |
$$ | . . . . . . . . . . . . . . . 6 . . . |
$$ | . . 2 . . . . . . . . . . . . 4 5 . . |
$$ | . . O X X . . . . 3 . . . . . , O . . |
$$ | . . X . . . O . . . . 1 . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Black gets the corner but White is strong. Black's wall won't die but has no eyes yet.

So I couldn't make up my mind and decide which one is best between "a" and "b".


This post by jlt was liked by 2 people: Bill Spight, Harleqin
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 Post subject: Re: Opening problems for AI: Problem 46
Post #4 Posted: Wed Aug 19, 2020 1:32 am 
Lives in sente
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Joaz Banbeck wrote:

Click Here To Show Diagram Code
[go]$$Wc The tight defense, white extends. Black is small and ugly.
$$ | . . . . . . . . . . . . . . . , . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . . O X X . . . . , . . . . . , O . . |
$$ | . . X . . . W . . . . 3 . . X . . . . |
$$ | . . . 2 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


I agree, but think 2 is gote.


This post by Shaddy was liked by 2 people: Bill Spight, Joaz Banbeck
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 Post subject: Re: Opening problems for AI: Problem 46
Post #5 Posted: Wed Aug 19, 2020 5:13 am 
Tengen
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Shaddy wrote:
...

Click Here To Show Diagram Code
[go]$$Wc The tight defense, white extends. Black is small and ugly.
$$ | . . . . . . . . . . . . . . . , . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . . O X X . . . . , . . . . . , O . . |
$$ | . . X . . . W . . . . 3 . . X . . . . |
$$ | . . . 2 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


I agree, but think 2 is gote.


I extended to C8 because I didn't like this:

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


As fights unfurl in each of the lower corners, black's groups will become stronger. White's middle group will look relatively weak.
White has three groups that will need stones, black has two.


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 Post subject: Re: Opening problems for AI: Problem 46
Post #6 Posted: Wed Aug 19, 2020 6:07 am 
Gosei

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

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 Post subject: Re: Opening problems for AI: Problem 46
Post #7 Posted: Wed Aug 19, 2020 6:52 am 
Tengen
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[admin]
Sorry, folks, we had a leak from an alternate dimension - one in which white had played at C3. TTBOOK, only one post got through.
Quick work by your admins has sealed the tear, and we expect no further problems from it.
[/admin]


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 Post subject: Re: Opening problems for AI: Problem 46
Post #8 Posted: Wed Aug 19, 2020 7:04 am 
Lives in sente
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Gomoto lives in dimension (3,3).


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 Post subject: Re: Opening problems for AI: Problem 46
Post #9 Posted: Wed Aug 19, 2020 9:41 am 
Gosei
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Intuitively I play B. Since this is an interesting problem, that probably means it's A. Let's look at it unbiased using two heuristics AI seem to have made prevalent in our thinking: sente and efficiency.

Click Here To Show Diagram Code
[go]$$Wc White A sente
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . . O X X . . . . , . . . . . , O . . |
$$ | . 2 X a . . O . . . . 3 . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Suppose :w1: is sente and Black replies at :b2: then we can see the exchange as forcing, White's stones leaving aji at A and having influence on the outside, so next White can play :w3: with added benefit.


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


If :w1: is not treated as sente, then we can expect this kind of result. White's stone is pincered but can still freely move and has A to work with. White's both corner-side developments look pretty efficient while Black's stones in the lower left don't. Perhaps :b8: should be at B but the problem remains.


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


If White pincers right away with :w1: then Black can execute :b2: and :b4 in sente and turn to :b6:
On the surface Black's stones don't look very efficient but we should into account that White's marked stone is also probably badly placed.


If I have to pick a diagram for White out of the above three, I pick White A gote. For Black I'd pick White B. So the most likely course for both is White A sente.

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Post #10 Posted: Wed Aug 19, 2020 10:42 am 
Lives in sente
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Joaz Banbeck wrote:
Shaddy wrote:
...

Click Here To Show Diagram Code
[go]$$Wc The tight defense, white extends. Black is small and ugly.
$$ | . . . . . . . . . . . . . . . , . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . . O X X . . . . , . . . . . , O . . |
$$ | . . X . . . W . . . . 3 . . X . . . . |
$$ | . . . 2 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


I agree, but think 2 is gote.


I extended to C8 because I didn't like this:

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


As fights unfurl in each of the lower corners, black's groups will become stronger. White's middle group will look relatively weak.
White has three groups that will need stones, black has two.

ok, i don't like this, but i think the problem is 3 not 1. maybe let's play 3 as kosumi from 3-4?

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 Post subject: Re: Opening problems for AI: Problem 46
Post #11 Posted: Wed Aug 19, 2020 12:07 pm 
Gosei
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@Joaz

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


Surely Black will play :b8: at A instead?

And so, :w7: is a mistake

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


White should simply play :w7: and then Black has to decide how to deal with the bottom. :b8: attacks the pincer but is already pincered back by the marked stone, which is disposable due to the :w1: - :b2: having been forcing upon Black.


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 Post subject: Re: Opening problems for AI: Problem 46
Post #12 Posted: Fri Aug 21, 2020 1:10 pm 
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This seems to have been a better problem than I anticipated. It has sparked some very interesting discussion. :)

The game is GoGoD 1706-01-08a, a Castle Game between Yasui Senkaku (W) and Honinbo Dochi. Dochi is a future Meijin.

The game continuation:

Click Here To Show Diagram Code
[go]$$Wcm10 Pincer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 5 . . |
$$ | . . . . . . . . . . . . . . . 4 . . . |
$$ | . . a . . . . . . . . . . . . 2 3 . . |
$$ | . . O X X . . . . , . . . . . , O . . |
$$ | . . X . . . O . b 6 . 1 . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

The pincer, :w10:, loses 13½% to a, according to Elf. Black presses against the bottom right corner and then invades with :b15:. :b15: figures to be a minor error, losing 7% to b.

Elf's variation for :b15: follows.

Click Here To Show Diagram Code
[go]$$Bcm15 Variation for :b15:
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . b . 0 . . . . . . . . . . . . . . |
$$ | . . . 8 . . . . . . . . . . . . O . . |
$$ | . . . 7 6 . . . . . . . . . . X . . . |
$$ | . . 2 9 . 4 c . 5 . . . . . . X O . . |
$$ | . . O X X . . . . d . . . . . , O . . |
$$ | . 3 X . . . O . 1 . . O . . X . . . . |
$$ | . . . a . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

:w16: extends on the left side. The tight pincer allows Black to descend with :b17: instead of playing the more defensive a. White continues strongly with :w18: and, after Black jumps to :b19:, the kosumi, :w20:, followed by the hane, :w22:.

Click Here To Show Diagram Code
[go]$$Bcm25 Variation for :b15:, continued
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . 7 . . . . . . . . . . . . |
$$ | . . . . O . . . . . . . . . . . . . . |
$$ | . . . O 4 3 . . . . . . . . . . O . . |
$$ | . . 5 X O . . 1 . . . . . . . X . . . |
$$ | . . O X . O . . X . . 6 . . . X O . . |
$$ | . . O X X 2 . . . , . . . . . , O . . |
$$ | . X X . . . O . X . . O . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

:b25: and :b27: strengthen Black's center stones with sente, then :b29: takes the bottom left corner. :w30: jumps into the center, and the :b31: continues to attack on a large scale, aiming at both White groups.

For :b11: Elf's top choice is no better than Dochi's play, but is instructive. :) (After looking again at Dochi's play, Elf slightly prefers it to its own top choice.)

Click Here To Show Diagram Code
[go]$$Bcm11 Variation for :b11:
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . . O X X . . . . 2 . . . . . , O . . |
$$ | . . X . . . O . . . . O . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

:b11: takes the bottom left corner and then :w12: settles the White formation on the bottom side. Black now plays tenuki.

Top choice: Extend towards the left side

Click Here To Show Diagram Code
[go]$$Wcm10 Extension
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 3 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . a . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . . O X X . . . . , . . . . . , O . . |
$$ | . b X . . . O . . c 4 . . . X . . . . |
$$ | . . . 2 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

:w10: extends and then :b11: makes eye shape, as we learned at Mother's knee. a and b are also joseki, and playable. Then :w12: makes a base and :b13: plays an extension cum pincer. :b13: could also be at c. Next, White plays tenuki.

By comparison with the variation for :b15:, White gets the extension in both cases, but here White makes a base instead of the pincer, which Black is able to invade and attack.

By comparison with the variation for :b11:, in that case Black gets the corner and White gets the pincer, while in this case Black gets the extension while White makes a base. Black is better on the bottom side, but Black has played one more stone there.

In both options for :b11: the White pincer becomes a liability. Dochi builds strength in the bottom right and then invades White's bottom side. Or Black takes the bottom left corner and White prevents the invasion, but then Black gets to play tenuki.


I am including the GoGoD SGF file for the whole game, because this is the game where Dochi plays a famous endgame tesuji. See B225. :)


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 Post subject: Re: Opening problems for AI: Problem 46
Post #13 Posted: Fri Aug 21, 2020 1:51 pm 
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What's interesting is an alternative move by Katago :

Click Here To Show Diagram Code
[go]$$Bc Alternative play by Katago
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 4 . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , 1 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . a . . . . . . . . . . . . . . . . |
$$ | . . 6 9 3 . . . . , . . . . . , 2 . . |
$$ | . . 7 . . . 8 . . W . b . . 5 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


It has lower policy than a, but about the same winrate/score, and become the "blue move" with enough playouts ( over 100k in my case)


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Post #14 Posted: Fri Aug 21, 2020 3:32 pm 
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Tryss wrote:
What's interesting is an alternative move by Katago :

Click Here To Show Diagram Code
[go]$$Bc Alternative play by Katago
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 4 . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , 1 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . a . . . . . . . . . . . . . . . . |
$$ | . . 6 9 3 . . . . , . . . . . , 2 . . |
$$ | . . 7 . . . 8 . . W . b . . 5 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


It has lower policy than a, but about the same winrate/score, and become the "blue move" with enough playouts ( over 100k in my case)


Very interesting! :D

Unlike the pincer, :wc: will not become a liability.

After White plays :wc:, what is KataGo's top choice for :b11:? a?

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 Post subject: Re: Opening problems for AI: Problem 46
Post #15 Posted: Fri Aug 21, 2020 4:10 pm 
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Black play at a, then white tenuki in the top right corner with P17. The game could look like this :

Click Here To Show Diagram Code
[go]$$Wc10
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . 3 . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . c 4 . . . . . . . . . . . 5 6 . . |
$$ | . . . . . . . . . . . . . . . 7 . . . |
$$ | . . b . . . . . . . . . . . . . 8 . . |
$$ | . . a . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 2 . . . . . . . . . . . . . . . . |
$$ | . . O X X . . . . , . . . . . , O . . |
$$ | . . X . . . O . . 1 . . . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


And the position after :w8: is interesting : Katago* consider the three moves a, b and c as very close. After 41389 playouts, the results are :
- a has 16k visits, 57.5%wr and +0.9pts
- b has 10k visits, 57.3%wr and +0.9pts
- c has 12k visits, 57.2%wr and +0.9pts

*) with the 20b network from the end of april, 7.5 komi and japanese rules


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Post #16 Posted: Fri Aug 21, 2020 7:20 pm 
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Tryss wrote:
What's interesting is an alternative move by Katago :

Click Here To Show Diagram Code
[go]$$Bc Alternative play by Katago
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 4 . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , 1 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . a . . . . . . . . . . . . . . . . |
$$ | . . 6 9 3 . . . . , . . . . . , 2 . . |
$$ | . . 7 . . . 8 . . W . b . . 5 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


It has lower policy than a, but about the same winrate/score, and become the "blue move" with enough playouts ( over 100k in my case)


Interestingly, the 40-block network seems to differ here a little, and prefer's ELF's move more.

KataGo seems to have different preferences than ELF in a number of other places in one of Bill's presented lines. It's hard to say whether for sure whether they are better or worse in some cases.

Prefers this slightly over "a":
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . O . . a W . . . . . . . . X O . . |
$$ | . . O X X . . . . . . . . . . , O . . |
$$ | . X X . . . O . X . . O . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]



Prefers this slightly over "a". Deeper search suggests this doesn't necessarily lead to a better result, but is also interesting and tricky for white to deal with:
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . O . . O . . a . . . . . . X O . . |
$$ | . . O X X . . 1 . . . . . . . , O . . |
$$ | . X X . . . O . X . . O . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Some variations for the diagonal:
One possible way. This way is a little favorable for black. Black has a bit of ugly shape on the left, but white is pretty busy everywhere.
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . 9 . . . . . . . . . . . . |
$$ | . . . . . . . . 0 . . . . . . . . . . |
$$ | . . 7 . 6 . 3 . . . . . . . . . O . . |
$$ | . . . 8 2 5 . 4 . . . . . . . X . . . |
$$ | . . O . . O . . . . . . . . . X O . . |
$$ | . . O X X 1 . B . . . . . . . , O . . |
$$ | . X X . . . O . X . . O . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


This way white pulls some tesujis out of a hat and fights back well, but black will still end up fine ends up fine anyways. The wedge is a sacrifice to let white break out, otherwise white would probably be in trouble here, but black will poke out too and continues to attack afterward.
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . 2 . . 6 . . . . . . . X . . . |
$$ | . . O . . O . 9 . . . . . . . X O . . |
$$ | . . O X X 1 . B . 3 5 . . . . , O . . |
$$ | . X X 8 7 . O . X 4 . O . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


This result is slightly favorable for black. The 8-9 exchange is locally ugly, but stops white from wedging at "a", and black is splitting both white groups while still poking ahead of white on the left side and making profit there.
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 0 . . . . . . . . . . . . O . . |
$$ | . . . 2 7 . 1 6 . . . . . . . X . . . |
$$ | . . O . . O 8 a . . . . . . . X O . . |
$$ | . . O X X 9 . B . 3 5 . . . . , O . . |
$$ | . X X . . . O . X 4 . O . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Unlike the above two cases which one might classify as just a difference in preference, in this case, KataGo thinks ELF's "a" for black is a noticeable mistake, and prefers 1-2-3 to take a sente exchange and not let white have the chance to run in the first place. White's lone stone isn't entirely dead, but black has control:
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 2 . O . . . . . . . . . . . . . . |
$$ | . . 1 O . a . . . . . . . . . . O . . |
$$ | . . . X O . . X . . . . . . . X . . . |
$$ | . . W X . O . . X . . 3 . . . X O . . |
$$ | . . W X X O . . . . . . . . . , O . . |
$$ | . X X . . . O . X . . O . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


White's cut doesn't work, which means that at the expense of strengthening white with a not-great exchange for the outside, black has managed to kill white's two stones in sente, instead of gote. Note that if black were to exchange "a"-"b" below, then white's "c" would work here due to a squeeze and ladder, this is the reason for not playing the peep and why sente is possible if the peep is omitted.

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


This post by lightvector was liked by 3 people: Bill Spight, ez4u, Gomoto
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 Post subject: Re: Opening problems for AI: Problem 46
Post #17 Posted: Fri Aug 21, 2020 9:28 pm 
Honinbo

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Wow! You gotta love those 18th century games. :D

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