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 Post subject: Interesting ladder position accidentally found by Uberdude
Post #1 Posted: Sun Feb 23, 2020 5:22 am 
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Uberdude wrote:
Played a game with the new #195 network. It was the first game in a long time that LZ had a ladder delusion (fast game at 15s a move so averaging about 3k playouts, needs 11k to realise ladder is bad and not play n10 atari...)

(Talking about this game)

Click Here To Show Diagram Code
[go]$$Wc19 White to play
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . O X . . . . . . . . . . . . |
$$ | . . X O O O X O O . . . . X . . . . . |
$$ | . . X X . X O X . . . . . . . X . . . |
$$ | . . . . . X O O O . . . . . . . X . . |
$$ | . . O . . X X X . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . O X . . . . . . . . O X X . . . |
$$ | . . . . . . . . . . . . . B O X O . . |
$$ | . . . O . . . . . . . . . . O O X X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . O O O O O . . . . O . . . . O X . . |
$$ | . X X X X O X . . . . . . . . O X . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Actually, there's more to this position than LZ-195 or even recent KataGo can easily see -- but LZ-258 gets this one. White to play: ladder or no ladder? How to continue? For human-style reading, you need to go five moves deep.

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #2 Posted: Sun Feb 23, 2020 5:51 am 
Honinbo

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Is it killing the corner?

Click Here To Show Diagram Code
[go]$$Wc1
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . O X . . . . . . . . . . . . |
$$ | . . X O O O X O O . . . . X . . . . . |
$$ | . . X X . X O X . . . . . . . X . . . |
$$ | . . . . . X O O O . . . . . . . X . . |
$$ | . . O . . X X X . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . O X . . . . . . . . O X X . . . |
$$ | . . . . . . . . . . . . W B O X O . . |
$$ | . . . O . . . . . . . W B B O O X X . |
$$ | . . . . . . . . . . W B B W . . O X . |
$$ | . . . . . . . . . W B B W . . . O X . |
$$ | . . . . . . . . W B B W . . . O X . . |
$$ | . . . . . . B W B B W . . . . O X . . |
$$ | . O O O O O B B B W O . . . . O X . . |
$$ | . X X X X O X W W . . . . . . O X . . |
$$ | . . . . W X W . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]


I don't know if it's worth it or not?

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #3 Posted: Sun Feb 23, 2020 11:15 am 
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Kirby wrote:
Is it killing the corner?

Click Here To Show Diagram Code
[go]$$Wc1
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . O X . . . . . . . . . . . . |
$$ | . . X O O O X O O . . . . X . . . . . |
$$ | . . X X . X O X . . . . . . . X . . . |
$$ | . . . . . X O O O . . . . . . . X . . |
$$ | . . O . . X X X . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . O X . . . . . . . . O X X . . . |
$$ | . . . . . . . . . . . . W B O X O . . |
$$ | . . . O . . . . . . . W B B O O X X . |
$$ | . . . . . . . . . . W B B W . . O X . |
$$ | . . . . . . . . . W B B W . . . O X . |
$$ | . . . . . . . . W B B W . . . O X . . |
$$ | . . . . . . B W B B W . . . . O X . . |
$$ | . O O O O O B B B W O . . . . O X . . |
$$ | . X X X X O X W W . . . . . . O X . . |
$$ | . . . . W X W . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]


I don't know if it's worth it or not?


I don't think it's worth it, white is losing so much around the failed ladder...

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #4 Posted: Sun Feb 23, 2020 12:54 pm 
Judan

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White doesn't need to play out the ladder and all the loss that entails BEFORE cutting in the corner, but can cut first, a standard ladder building tesuji that I think most mid dan amateurs with an eye for fancy tesuji like myself can find without much trouble. Bots on the other hand without the ability to chunk the ladder reading and think logically struggle. This exchange does make the ladder work, but also is a locally bad exchange (but not super bad), so black could then switch to simply not running out the ladder stone but just atari from the outside (or complicated cut at a), which also makes the cutting stone a slightly bad exchange. Which is worse is hard to say.

Click Here To Show Diagram Code
[go]$$Wc19 ladder making tesuji
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . O X . . . . . . . . . . . . |
$$ | . . X O O O X O O . . . . X . . . . . |
$$ | . . X X . X O X . . . . . . . X . . . |
$$ | . . . . . X O O O . . . . . . . X . . |
$$ | . . O . . X X X . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . 6 4 . . . . . |
$$ | . . . O X . . . . . . . . O X X . . . |
$$ | . . . . . . . . . . . . 3 . O X O . . |
$$ | . . . O . . . . . . . . . 5 O O X X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . a O X . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . O O O O O . . . . O . . . . O X . . |
$$ | . X X X X O X . . . . . . . . O X . . |
$$ | . . . . . X 1 2 . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]


Of course black might resist and go for a trade. At first glance this seems not obviously terrible for either. Both gain and lose a lot. But I think I prefer White's big territory gain because that's a huge swing, whilst the stones White loses on the right can be considered kikashi with the black answers and are not many points in themselves, Black's top right was already solid, the centre thickness is nice but not easy to make 40 points from because I don't think the wall below will die.

Click Here To Show Diagram Code
[go]$$Wc19 resistance
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . O X . . . . . . . . . . . . |
$$ | . . X O O O X O O . . . . X . . . . . |
$$ | . . X X . X O X . . . . . . . X . . . |
$$ | . . . . . X O O O . . . . . . . X . . |
$$ | . . O . . X X X . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . O X . . . . . . . . O X X . . . |
$$ | . . . . . . . . . . . . . B O X O . . |
$$ | . . . O . . . . . . . . . 2 O O X X . |
$$ | . . . . . . . . . . . . . . 4 . O X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . O O O O O . . . . O . . . . O X . . |
$$ | . X X X X O X . . . . . . . . O X . . |
$$ | . . . . 3 X 1 . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #5 Posted: Sun Feb 23, 2020 1:24 pm 
Gosei
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Click Here To Show Diagram Code
[go]$$Wc19 White to play
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . O X . . . . . . . . . . . . |
$$ | . . X O O O X O O . . . . X . . . . . |
$$ | . . X X . X O X . . . . . . . X . . . |
$$ | . . . . . X O O O . . . . . . . X . . |
$$ | . . O . . X X X . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . O X . . . . . . . 1 O X X . . . |
$$ | . . . . . . . . . . . . . B O X O . . |
$$ | . . . O . . . . . . . . . . O O X X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . O O O O O . . . . O . . . . O X . . |
$$ | . X X X X O X . . . . . . . . O X . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]


I would play here. I'm also taking the upper left into account.

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #6 Posted: Sun Feb 23, 2020 2:15 pm 
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Tried one of the in-training 30 block networks that hasn't been released yet. Indeed Kata doesn't get this one right on its own, but interactive analysis with it in Lizzie quickly suggests that the correct way for white to play is to play precisely two steps of the ladder, before cutting G2.

Playing either one or three steps of the ladder before cutting is almost as good.

More than 3 steps starts to get much worse. In the extreme, playing out the entire ladder to kill the lower left is bad, white loses too much.

How about zero steps? Playing zero steps of the ladder and cutting G2 is not so good. Black will eat your G2 stone and give up the ladder as in Uberdude's diagram, and get away cheap. And actually, if you're going to play zero steps of the ladder before breaking it, then H2 is a better ladder breaker, since it loses less. H2 still works as a breaker because the L4 stone lets white shift the ladder down one space extra.

However, H2 is only a good ladder breaker if you're playing zero steps of the ladder. If you play one or more steps first, then H2 isn't forceful enough to compensate the loss from black escaping the partially played ladder.

If white begins the ladder, planning to run it precisely 1 to 3 steps before cutting G2, and black knows this, then of course black should immediately accept the loss and not attempt to save the ladder stone.

How does this compare to LZ?

Anyways, as for how to make the search capable of always solving things like this on its own... hmm...


This post by lightvector was liked by 5 people: Dusk Eagle, Kirby, Maharani, Uberdude, xela
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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #7 Posted: Sun Feb 23, 2020 2:42 pm 
Judan

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Yeah I was going to suggest playing some moves of the ladder as a probe to make it heavier before making the lossy cut, like Lee Sedol did in his famous ladder game, but too hard for a Sunday evening.

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #8 Posted: Sun Feb 23, 2020 6:21 pm 
Honinbo

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Hehe, yeah it makes sense not to play out the entire ladder!

Like some bots, I think I’m lacking the logic aspect, sometimes :blackeye:

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #9 Posted: Sun Feb 23, 2020 6:24 pm 
Honinbo

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Knotwilg wrote:
Click Here To Show Diagram Code
[go]$$Wc19 White to play
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . O X . . . . . . . . . . . . |
$$ | . . X O O O X O O . . . . X . . . . . |
$$ | . . X X . X O X . . . . . . . X . . . |
$$ | . . . . . X O O O . . . . . . . X . . |
$$ | . . O . . X X X . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . O X . . . . . . . 1 O X X . . . |
$$ | . . . . . . . . . . . . . B O X O . . |
$$ | . . . O . . . . . . . . . . O O X X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . O O O O O . . . . O . . . . O X . . |
$$ | . X X X X O X . . . . . . . . O X . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]


I would play here. I'm also taking the upper left into account.


What aspect of the upper left do you mean? Black and white both seem somewhat safe to me, but I’m known to miss some nuances.

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #10 Posted: Mon Feb 24, 2020 1:33 am 
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lightvector wrote:
Anyways, as for how to make the search capable of always solving things like this on its own... hmm...

I notice that after two steps of the ladder, KataGo (1.3.2 most recent published 20b network) starts looking at H3 as a ladder breaker (policy value 0.2%, but the "high policy" moves at P7 or P8 don't work out so well, so KataGo goes down the list of alternatives). Only after about 15,000 playouts does it start to examine G2 (policy value less than 0.1%) -- and then correctly assess how good the move is. With those numbers, of course it doesn't easily see G2 in advance.

I'm thinking this is a blind spot in KataGo's sense of shape. With KataGo training so much more efficiently than LZ, it hasn't seen quite so many million go positions, so it makes sense to me that it will sometimes miss vital points of shapes. Then again, LZ doesn't immediately get this one either...

lightvector wrote:
How does this compare to LZ?

For LZ-258, about the same. LZ wants to play the ladder, expecting black not to pull out of atari but to reply at O12 instead. When black does pull out of atari, LZ's first choice is to give up on the ladder and connect at Q7. After about 10,000 playouts, it finds G2 two moves down the search tree. The difference is that it doesn't seem to explore H3 at all, it goes to G2 first. But on medium numbers of playouts, it's choosing the same game moves KataGo, just with slightly different "reasoning" behind it.

It would be fun, but time-consuming, to compare this with a bunch of other LZ networks.

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #11 Posted: Mon Feb 24, 2020 1:42 am 
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Some KataGo evaluations, for people who can't conveniently do this at home. All with 20,000+ playouts

Long ladder variation
White takes too much damage in exchange for the corner. Black winrate 92%, score +7.6 points.
Click Here To Show Diagram Code
[go]$$Wc1
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . O X . . . . . . . . . . . . |
$$ | . . X O O O X O O . . . . X . . . . . |
$$ | . . X X . X O X . . . . . . . X . . . |
$$ | . . . . . X O O O . . . . . . . X . . |
$$ | . . O . . X X X . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . O X . . . . . . . . O X X . . . |
$$ | . . . . . . . . . . . . W B O X O . . |
$$ | . . . O . . . . . . . W B B O O X X . |
$$ | . . . . . . . . . . W B B W . . O X . |
$$ | . . . . . . . . . W B B W . . . O X . |
$$ | . . . . . . . . W B B W . . . O X . . |
$$ | . . . . . . B W B B W . . . . O X . . |
$$ | . O O O O O B B B W O . . . . O X . . |
$$ | . X X X X O X W W . . . . . . O X . . |
$$ | . . . . W X W . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]


Uberdude's variation 1
About as close to an even position as you can get. Black winrate 53%, score +0.6 points
Click Here To Show Diagram Code
[go]$$Wc19 ladder making tesuji
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . O X . . . . . . . . . . . . |
$$ | . . X O O O X O O . . . . X . . . . . |
$$ | . . X X . X O X . . . . . . . X . . . |
$$ | . . . . . X O O O . . . . . . . X . . |
$$ | . . O . . X X X . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . 6 4 . . . . . |
$$ | . . . O X . . . . . . . . O X X . . . |
$$ | . . . . . . . . . . . . 3 . O X O . . |
$$ | . . . O . . . . . . . . . 5 O O X X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . O O O O O . . . . O . . . . O X . . |
$$ | . X X X X O X . . . . . . . . O X . . |
$$ | . . . . . X 1 2 . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]


Uberdude's variation 2
The trade is too good for white. White winrate 99%, score +15.5 points.
Click Here To Show Diagram Code
[go]$$Wc19 resistance
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . O X . . . . . . . . . . . . |
$$ | . . X O O O X O O . . . . X . . . . . |
$$ | . . X X . X O X . . . . . . . X . . . |
$$ | . . . . . X O O O . . . . . . . X . . |
$$ | . . O . . X X X . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . O X . . . . . . . . O X X . . . |
$$ | . . . . . . . . . . . . . B O X O . . |
$$ | . . . O . . . . . . . . . 2 O O X X . |
$$ | . . . . . . . . . . . . . . 4 . O X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . O O O O O . . . . O . . . . O X . . |
$$ | . X X X X O X . . . . . . . . O X . . |
$$ | . . . . 3 X 1 . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]


Knotwilg's variation
If you don't find the ladder-maker move, this is a pretty good alternative. Black winrate 60%, score +1.7 points.
Click Here To Show Diagram Code
[go]$$Wc19 White to play
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . O X . . . . . . . . . . . . |
$$ | . . X O O O X O O . . . . X . . . . . |
$$ | . . X X . X O X . . . . . . . X . . . |
$$ | . . . . . X O O O . . . . . . . X . . |
$$ | . . O . . X X X . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . O X . . . . . . . 1 O X X . . . |
$$ | . . . . . . . . . . . . . B O X O . . |
$$ | . . . O . . . . . . . . . . O O X X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . O O O O O . . . . O . . . . O X . . |
$$ | . X X X X O X . . . . . . . . O X . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]


The actual game continuation.
Black winrate 69%, score +3.1 points.
Click Here To Show Diagram Code
[go]$$Wc19
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . O X . . . . . . . . . . . . |
$$ | . . X O O O X O O . . . . X . . . . . |
$$ | . . X X . X O X . . . . . . . X . . . |
$$ | . . . . . X O O O . . . . . . . X . . |
$$ | . . O . . X X X . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . O X . . . . . . . . O X X . . . |
$$ | . . . . . . . . . . . . 1 B O X O . . |
$$ | . . . O . . . . . . . . . 2 O O X X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . 3 O X . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . O O O O O . . . . O . . . . O X . . |
$$ | . X X X X O X . . . . . . . . O X . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]



A recommended continuation (there's actually a few different ways for black to bail out, with similar evaluations).
Edit: "recommended" means recommended for white. The :b2: in this variation is a serious mistake as Uberdude points out.
Similar to Uberdude variation 1, but white's capture is a bit bigger, and white therefore has a bit more influence as well as the extra four points. White winrate 96, score +7.7 points.
Click Here To Show Diagram Code
[go]$$Wc19
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . O X . . . . . . . . . . . . |
$$ | . . X O O O X O O . . . . X . . . . . |
$$ | . . X X . X O X . . . . . . . X . . . |
$$ | . . . . . X O O O . . . . . . . X . . |
$$ | . . O . . X X X . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . 8 . . . . . |
$$ | . . . O X . . . . . . . . O X X . . . |
$$ | . . . . . . . . . . . . 1 B O X O . . |
$$ | . . . O . . . . . . . 7 4 2 O O X X . |
$$ | . . . . . . . . . . . . 9 3 . . O X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . O O O O O . . . . O . . . . O X . . |
$$ | . X X X X O X . . . . . . . . O X . . |
$$ | . . . . . X 5 6 . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]


Last edited by xela on Tue Feb 25, 2020 12:11 am, edited 2 times in total.
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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #12 Posted: Mon Feb 24, 2020 2:43 am 
Judan

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Xela, thanks. In the last digram if black can anticipate the G2 tesuji after a few ladder ataris presumably the best choice is to immediately bail out with outside atari, in which case you get the same as uberdude variation 1 but without White making the G2 lossy exchange. How much does that lose? 10-15%? In which case it's kinda funny that optimal play because you can see G2 tesuji and playing out the ladder to make it heavier advanced technique, and being too dumb to read the ladder correctly result in the same moves!

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #13 Posted: Mon Feb 24, 2020 5:21 am 
Lives in gote

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Right. White N10 atari, black O12 immediately leads to white winrate of 64%, white 1.3 points up. Much better for black than playing out a move of the ladder and "falling into the G2 trap". Or to put it another way, playing G2 too early costs white about 17% in winrate (comparing with "Uberdude variation 1").

Yes, I appreciate the irony. I was searching for "ladder fail" positions so I could look at how more recent LZ versions handle ladders (how much does it find out via playouts, and how much is already there in the policy network?) It's surprisingly hard to find specific positions, despite lots of "LZ doesn't get ladders" complaints. And then I run into one where an older LZ played the right move for the wrong reasons!

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #14 Posted: Mon Feb 24, 2020 6:46 am 
Honinbo

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You know, we don't have to call the first variation "Kirby's variation". I wouldn't be opposed to a different name for it :lol:

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #15 Posted: Mon Feb 24, 2020 7:48 am 
Judan

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Xela, if you want a ladder test for bots try http://www.go4go.net/go/games/sgfview/84421. Kim jiseok resigned in a position LZ thought he was ahead because of misunderstanding ladders in the bad aji around a kill. At least it did on the old version at the time; LZ thought white needed to spend a move to save 3 stones on outside against a black ladder that doesn't work, so would let black capture inside stones to live but actually white can save inside stones to kill and nothing quite works for black outside (some variations quite long).

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #16 Posted: Mon Feb 24, 2020 2:53 pm 
Lives in gote

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Link doesn't work for me ("The website encountered an unexpected error. Please try again later." and a scary-looking exception involving MySQL). Are you able to share the position or the SGF?

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #17 Posted: Mon Feb 24, 2020 4:06 pm 
Honinbo

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I can't access the link, either.

Any chance it's this game?


Total guess, just based on the comment description :-S

But my version of leelaz thinks white is ahead here.

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #18 Posted: Mon Feb 24, 2020 4:12 pm 
Judan

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Yes, that's the one, Shin Jinseo winning in under 100 moves.

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #19 Posted: Mon Feb 24, 2020 6:03 pm 
Honinbo

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Complicated game. The first interesting choice is this one:
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . O O . . |
$$ | . . . . . . . . . . . W . . . O X . . |
$$ | . . . O . X . . . X . C . X . , X . . |
$$ | . . . . O X . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


I was curious about black just playing the marked intersection - it's what one might consider if they didn't want to resist. This is what I saw after I briefly checked with a bot:

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


I guess white has more influence this way - though, I don't totally get it.

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 Post subject: Re: Interesting ladder position accidentally found by Uberdu
Post #20 Posted: Tue Feb 25, 2020 12:12 am 
Lives in gote

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Kirby wrote:
You know, we don't have to call the first variation "Kirby's variation". I wouldn't be opposed to a different name for it :lol:

Better now?

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