KataGo @ Igo Hatsuyoron 120

Bill Spight · Post by **Bill Spight** » Wed Oct 23, 2019 10:19 am

Brief note on understanding

Understanding is a fuzzy concept. Do computer players understand their plays? One test of human understanding is whether someone can give an explanation for something. Bots currently do not do that. However, another idea of understanding is to have relevant concepts. For instance a snapback is a certain type of play along with its possible followers in certain positions. The bots plainly understand snapbacks in that they find them and play them, not only making the initial play, but making the followups if necessary. Similarly, they understand nakade, because they make the plays, but I am not sure that their understanding is as good as that of an amateur dan players. My guess is that they do not count liberties, but rely upon reading.

BTW, many years ago psychologist Jerome Bruner showed that we can regard concepts and strategies as the same thing. Not that we have to, OC.

Cassandra · Post by **Cassandra** » Thu Oct 24, 2019 5:49 am

Click Here To Show Diagram Code: [go]$$Wcm102 W 102 (KataGo's crosscut after Yamada's tsuke) $$ +---------------------------------------+ $$ | . . . . . . . . . . . . X . . . O X . | $$ | . . . . B W ? X O O . X O X O . . O . | $$ | . . . . 1 X . O . . . X O . . O O . . | $$ | . X O , . . . . . O . X . O O X . . . | $$ | . . X X X X O O O . O X X . X X O O . | $$ | . X . O O O X X X O . . X . X O . O . | $$ | O O O O . X O O X X O O . O X . . X . | $$ | O X . X . X . O O X O . . . X X X X X | $$ | O X . X . . . O X X O . X X X X O O O | $$ | X O O X . X . O X O O X X O O O O X . | $$ | X X O O X . . O X O . X O O O . X X X | $$ | X X . O X . . O X O . X O O X X X O O | $$ | X X O O X . . O X O . X O O O X X X O | $$ | X O O . O X . O X O . X X O O O X O O | $$ | X O X O . X . O X O X . O X X X O O O | $$ | O X X X X . . O X O O O O X O X O O X | $$ | O . . . O X . O X X X X X . O X X O X | $$ | O . X . . . X O O O O O O X O X . O X | $$ | . X . . . . . O . . . . O X X X . O . | $$ +---------------------------------------+[/go]

We were very surprised that KataGo preferred the crosscut of 102 (after Yamada's tsuke = marked stones) to drawing-back with a move at G18.

On the other hand, this move might be standard endgame repertoire that we amateurs were absolutely not aware of.

Click Here To Show Diagram Code: [go]$$Bcm101 (B 103 - B 107) $$ +---------------------------------------+ $$ | . . . 7 4 . . . . . . . X . . . O X . | $$ | . . . 5 X O 6 X O O . X O X O . . O . | $$ | . . . 3 O X . O . . . X O . . O O . . | $$ | . X O , . . . . . O . X . O O X . . . | $$ | . . X X X X O O O . O X X . X X O O . | $$ | . X . O O O X X X O . . X . X O . O . | $$ | O O O O . X O O X X O O . O X . . X . | $$ | O X . X . X . O O X O . . . X X X X X | $$ | O X . X . . . O X X O . X X X X O O O | $$ | X O O X . X . O X O O X X O O O O X . | $$ | X X O O X . . O X O . X O O O . X X X | $$ | X X . O X . . O X O . X O O X X X O O | $$ | X X O O X . . O X O . X O O O X X X O | $$ | X O O . O X . O X O . X X O O O X O O | $$ | X O X O . X . O X O X . O X X X O O O | $$ | O X X X X . . O X O O O O X O X O O X | $$ | O . . . O X . O X X X X X . O X X O X | $$ | O . X . . . X O O O O O O X O X . O X | $$ | . X . . . . . O . . . . O X X X . O . | $$ +---------------------------------------+[/go]

We will display KataGo's main variation only.

Perhaps there is someone in the honoured audience who wants to refute KataGo? We have not succeeded so far.
Please remember that this is a sheer endgame problem. It has nothing at all to do with the rest of the board (ko-fights excluded).

Click Here To Show Diagram Code: [go]$$Wcm108 (W 108 - B 117) $$ +---------------------------------------+ $$ | . . . X O . . . . . . . X . . . O X . | $$ | . . . X X O O X O O . X O X O . . O . | $$ | . . . X O X 9 O . . . X O . . O O . . | $$ | . X O , . 0 6 . . O . X . O O X . . . | $$ | . . X X X X O O O . O X X . X X O O . | $$ | . X . O O O X X X O . . X . X O . O . | $$ | O O O O . X O O X X O O . O X . . X . | $$ | O X . X . X . O O X O . . . X X X X X | $$ | O X . X . . . O X X O . X X X X O O O | $$ | X O O X . X . O X O O X X O O O O X . | $$ | X X O O X . . O X O . X O O O . X X X | $$ | X X . O X . . O X O . X O O X X X O O | $$ | X X O O X . . O X O . X O O O X X X O | $$ | X O O . O X . O X O . X X O O O X O O | $$ | X O X O . X . O X O X . O X X X O O O | $$ | O X X X X 8 . O X O O O O X O X O O X | $$ | O . . . O X 7 O X X X X X . O X X O X | $$ | O . X . 2 1 X O O O O O O X O X . O X | $$ | . X . . 4 3 5 O . . . . O X X X . O . | $$ +---------------------------------------+[/go]

The endgame continues on the lower edge with White's "usual" move at 108.

Click Here To Show Diagram Code: [go]$$Wcm118 (W 118 - B 123) $$ +---------------------------------------+ $$ | . . . X O . . . . . . . X X . . O X . | $$ | . . . X X O O X O O . X O X O . . O . | $$ | . . . X O X O O . . . X O O . O O . . | $$ | . X O , . X X 2 3 O . X . O O X . . . | $$ | . . X X X X O O O . O X X . X X O O . | $$ | . X . O O O X X X O . . X . X O . O . | $$ | O O O O 1 X O O X X O O . O X . . X . | $$ | O X . X . X . O O X O . . . X X X X X | $$ | O X . X . . . O X X O . X X X X O O O | $$ | X O O X . X . O X O O X X O O O O X . | $$ | X X O O X 6 . O X O . X O O O . X X X | $$ | X X . O X . . O X O . X O O X X X O O | $$ | X X O O X . . O X O . X O O O X X X O | $$ | X O O 5 O X . O X O . X X O O O X O O | $$ | X O X O 4 X . O X O X . O X X X O O O | $$ | O X X X X X . O X O O O O X O X O O X | $$ | O . . . O X O O X X X X X . O X X O X | $$ | O . X . X O . O O O O O O X O X . O X | $$ | . X . . X O O O . . . . O X X X . O . | $$ +---------------------------------------+[/go]

Eventually, White 118 is her bad-shape move in the left centre that costs Black one point.

Click Here To Show Diagram Code: [go]$$Wcm124 (W 124 - W 128) $$ +---------------------------------------+ $$ | . . . X O 3 . . . . . . X X . . O X . | $$ | . . . X X O O X O O . X O X O . . O . | $$ | . . . X O X O O . . . X O O . O O . . | $$ | . X O , . X X X O O . X . O O X 4 5 . | $$ | . . X X X X O O O . O X X . X X O O . | $$ | . X . O O O X X X O . . X . X O . O . | $$ | O O O O O X O O X X O O . O X . . X . | $$ | O X . X 1 X . O O X O . . . X X X X X | $$ | O X . X 2 . . O X X O . X X X X O O O | $$ | X O O X . X . O X O O X X O O O O X . | $$ | X X O O X X . O X O . X O O O . X X X | $$ | X X . O X . . O X O . X O O X X X O O | $$ | X X O O X . . O X O . X O O O X X X O | $$ | X O O O O X . O X O . X X O O O X O O | $$ | X O X O X X . O X O X . O X X X O O O | $$ | O X X X X X . O X O O O O X O X O O X | $$ | O . . . O X O O X X X X X . O X X O X | $$ | O . X . X O . O O O O O O X O X . O X | $$ | . X . . X O O O . . . . O X X X . O . | $$ +---------------------------------------+[/go]

For the sake of simplicity for calculation, let us assume these moves here, which might not necessarily be played in order.

White's connection at 126 is not related to the Main Semeai, so White loses a move therein. Therefore, Black is able to play an additional forcing move at the right, e.g. at 127.

Click Here To Show Diagram Code: [go]$$Bc (White's gains and losses) $$ +---------------------------------------+ $$ | . . . X O O T T . . . . X X . . O X . | $$ | . . . X X O O X O O . X O X O . . O . | $$ | . . . X O X O O . . . X O O . O O . . | $$ | . X O , . X X X O O . X . O O X X P . | $$ | . . X X X X O O P . O X X . X X O O . | $$ | . X . O O O X X X O . . X . X O . O . | $$ | O O O O O X O O X X O O . O X . . X . | $$ | O X . X O X . O O X O . . . X X X X X | $$ | O X . X X . . O X X O . X X X X O O O | $$ | X O O X . X . O X O O X X O O O O X . | $$ | X X O O X X . O X O . X O O O . X X X | $$ | X X . O X . . O X O . X O O X X X O O | $$ | X X O O X . . O X O . X O O O X X X O | $$ | X O O O O X . O X O . X X O O O X O O | $$ | X O X O X X . O X O X . O X X X O O O | $$ | O X X X X X . O X O O O O X O X O O X | $$ | O . . . O X O O X X X X X . O X X O X | $$ | O . X . X O . O O O O O O X O X . O X | $$ | . X . . X O O O . . . . O X X X . O . | $$ +---------------------------------------+[/go]

White lost two points of territory (crossed), one in the centre and one at the right.

On the upper edge, she gains two points of territory in return (triangled).

Click Here To Show Diagram Code: [go]$$Bc (Black's losses) $$ +---------------------------------------+ $$ | . . . Z O O . . . . . . X X . . O X . | $$ | . . . Z X O O X O O . X O X O . . O . | $$ | . . . X O X O O . . . X O O . O O . . | $$ | . X O , . X X X O O . X . O O X X O . | $$ | . . X X X X O O O . O X X . X X O O . | $$ | . X . O O O X X X O . . X . X O . O . | $$ | O O O O O X O O X X O O . O X . . X . | $$ | O X . X O X . O O X O . . . X X X X X | $$ | O X . X X . . O X X O . X X X X O O O | $$ | X O O X . X . O X O O X X O O O O X . | $$ | X X O O X X . O X O . X O O O . X X X | $$ | X X . O X . . O X O . X O O X X X O O | $$ | X X O O X . . O X O . X O O O X X X O | $$ | X O O O O X . O X O . X X O O O X O O | $$ | X O X O X X . O X O X . O X X X O O O | $$ | O X X X X X . O X O O O O X O X O O X | $$ | O . . . O X O O X X X X X . O X X O X | $$ | O . X . X O . O O O O O O X O X . O X | $$ | . X . . X O O O . . . . O X X X . O . | $$ +---------------------------------------+[/go]

Black's additional loss of territory in the upper left corner is two points (crossed).

The final score is reduced by this margin. Instead of ending in jigo, now the game's result is
W + 2.

+ + + + + + + + + + + + + + + + + + + +
+ + + + + + + + + + + + + + + + + + + +

Have we reached the end of the story?
We do not have the slightest idea ...

lightvector · Post by **lightvector** » Sat Oct 26, 2019 5:18 am

A major caveat that Cassandra may have forgotten to mention: W+2 is a potentially misleading result to conclude, because KataGo uses area-scoring (i.e. Chinese-style scoring). What KataGo itself "believes" currently is NOT W+2 territory-scoring, but rather is W+1 area-scoring.

Assuming no surprising endgame details (i.e. being able to defer a final ko fight until after filling all dame, or finishing the game somehow with certain kinds of seki), W+1 area-scoring is equivalent to either W+1 territory-scoring OR W+2 territory-scoring.

Therefore, even if there are no larger mistakes (again, it's not totally certain that KataGo has analyzed everything correctly) it is easily possible that KataGo is having black play a line that is slack by 1 point by territory scoring, because such a line would still be exactly identical in score and just as "optimal" under area scoring.

Bill Spight · Post by **Bill Spight** » Sat Oct 26, 2019 7:30 am

lightvector wrote:Therefore, even if there are no larger mistakes (again, it's not totally certain that KataGo has analyzed everything correctly) it is easily possible that KataGo is having black play a line that is slack by 1 point by territory scoring, because such a line would still be exactly identical in score and just as "optimal" under area scoring.

That is why Berlekamp's, Wolfe's, and my zero komi problems have White to play and win instead of Black. Normally, on the 19x19 jigo by territory scoring is a Black win by area scoring, so White has to win by both forms of scoring. It might be interesting to set up the problem with colors reversed and White to play, and see what KataGo says.

lightvector · Post by **lightvector** » Sat Oct 26, 2019 8:08 am

Bill, I think there would be no difference, the parity would come out the same way.

In fact, the neural net is not even told the absolute color of the player. It's only told in terms of "my color" and "opponent color" and "number of komi points added/subtracted from my own color's perspective". So it literally can't tell the difference between color inversion if komi adjusted appropriately, or if komi = 0 in the first place.

(at least, if I'm not forgetting some detail of how I'm doing things)

wineandgolover · Post by **wineandgolover** » Sun Oct 27, 2019 10:38 am

Bill Spight wrote:My guess is that they do not count liberties, but rely upon reading.

I’m not sure I buy this, because the bots are high dan with zero playouts. Doesn’t that mean liberty counting likely plays a role for both value and policy aspects of the bots?

Bill Spight · Post by **Bill Spight** » Sun Oct 27, 2019 11:16 am

wineandgolover wrote:
Bill Spight wrote:My guess is that they do not count liberties, but rely upon reading.
I’m not sure I buy this, because the bots are high dan with zero playouts. Doesn’t that mean liberty counting likely plays a role for both value and policy aspects of the bots?

We know that some animals, who apparently do not count, are able to distinguish between five and six items at a glance. How many liberties top neural net bots are able to distingush, I don't know. But nakade liberties, which was the context of my remark, are another animal, as they require distinguishing under the stones liberties, and accounting for sente plays as well as gote fills. On top of which, we know that semeai are weak spots for today's bots. Counting liberties makes semeai much easier than not counting liberties.

Bill Spight · Post by **Bill Spight** » Sun Oct 27, 2019 11:42 am

lightvector wrote:Bill, I think there would be no difference, the parity would come out the same way.

Thanks, that was my guess.

Edit; But, since there is no captured stone in the mirror problem, won't the territory result also be Black +1?

Bojanic · Post by **Bojanic** » Mon Oct 28, 2019 7:15 am

Cassandra wrote:
$$Wcm94 W 94 (KataGo's Atari)
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . X . . . O X . |
$$ | . . . . . . . X O O . X O X O . . O . |
$$ | . . . . . X . O . . . X O . . O O . . |
$$ | . X O , . . . . . O . X . O O X . . . |
$$ | . . X X X X O O O . O X X . X X O O . |
$$ | . X . O O O X X X O . . X . X O . O . |
$$ | O O O O . X O O X X O O . O X . . X . |
$$ | O X . X . X . O O X O . . . X X X X X |
$$ | O X . X . . . O X X O . X X X X O O O |
$$ | X O O , . X . O X O O X X O O O O X . |
$$ | X X . O X . . O X O . X O O O . X X X |
$$ | X . . O X . . O X O . X O O X X X O O |
$$ | X X O 1 X . . O X O . X O O O X X X O |
$$ | X O O X O X . O X O . X X O O O X O O |
$$ | X O X . . X . O X O X . O X X X O O O |
$$ | O X X , X . . O X O O O O X O X O O X |
$$ | O . . . O X . O X X X X X ? O X X O X |
$$ | O . X . . . X O O O O O O X O X . O X |
$$ | . X . . . . . O . . . . O X X X . O . |
$$ +---------------------------------------+
Click Here To Show Diagram Code
[go]$$Wcm94 W 94 (KataGo's Atari) $$ +---------------------------------------+ $$ | . . . . . . . . . . . . X . . . O X . | $$ | . . . . . . . X O O . X O X O . . O . | $$ | . . . . . X . O . . . X O . . O O . . | $$ | . X O , . . . . . O . X . O O X . . . | $$ | . . X X X X O O O . O X X . X X O O . | $$ | . X . O O O X X X O . . X . X O . O . | $$ | O O O O . X O O X X O O . O X . . X . | $$ | O X . X . X . O O X O . . . X X X X X | $$ | O X . X . . . O X X O . X X X X O O O | $$ | X O O , . X . O X O O X X O O O O X . | $$ | X X . O X . . O X O . X O O O . X X X | $$ | X . . O X . . O X O . X O O X X X O O | $$ | X X O 1 X . . O X O . X O O O X X X O | $$ | X O O X O X . O X O . X X O O O X O O | $$ | X O X . . X . O X O X . O X X X O O O | $$ | O X X , X . . O X O O O O X O X O O X | $$ | O . . . O X . O X X X X X ? O X X O X | $$ | O . X . . . X O O O O O O X O X . O X | $$ | . X . . . . . O . . . . O X X X . O . | $$ +---------------------------------------+[/go]

Sorry to disturb, but why would white not play at any of diagrams on this topic on O3, capture black dragon in the center, and therefore capture black's right seki group and even left big eye group?

This black's group is in atari during entire analysis, and eating it would finish game in instant.

Cassandra · Post by **Cassandra** » Mon Oct 28, 2019 7:25 am

Bojanic wrote:This black's group is in atari during entire analysis, and eating it would finish game in instant.

Capturing the Hanezeki's Tail costs White about 24 points overall

The Hanezeki will be resolved (all of White's stone in the lower right corner will be captured), having the final effect that Black's big group in the upper right lives.

If White captured the Tail so early in the game, she would not have got the large amount of prisoners, which she otherwise gets during the successive reduction of the Nakade at the left edge.

Bojanic · Post by **Bojanic** » Mon Oct 28, 2019 7:38 am

I see now, eating back 4 stones would create more liberties for W in lower right group.

Bojanic · Post by **Bojanic** » Mon Oct 28, 2019 7:48 am

What happens if at this, or some earlier stage, white starts to fill in black's liberties in upper right?

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

Black has some 17 liberties, it is difficult to count how many white has on the left.

But the idea is, if white eats big black group in center, it will take him 6 moves for black to eat seki group and liberate his upper right group.

Cassandra · Post by **Cassandra** » Mon Oct 28, 2019 7:53 am

Bojanic wrote:What happens if at this, or some earlier stage, white starts to fill in black's liberties in upper right?

Black occupies the same number of liberties of White's group at the left edge.

We call this sequence of these exchanges of liberties "The Main Semeai".

It can be played before the remaining "usual" endgame (because these moves do not affect the Main Semeai), or after, as we have choosen in our presentation, following a recommendation of Prof. Jeong from Korea (just because the outcome of the Main Semeai is already decided).

+ + + + +

You might want to visit our website (see my signature below). Nearly every question you might have is already answered there.

But, as a matter of course, I will still answer your questions here.

Bojanic · Post by **Bojanic** » Mon Oct 28, 2019 8:03 am

Cassandra wrote:Black occupies the same number of liberties of White's group at the left edge.

If it is the same number of liberties, white would win semeai.
When they come to five liberties each, white can eat center group, and capture black's group.

Do you have variation with start of liberty filling?

Bojanic · Post by **Bojanic** » Mon Oct 28, 2019 8:18 am

Cassandra wrote:You might want to visit our website (see my signature below). Nearly every question you might have is already answered there.

But, as a matter of course, I will still answer your questions here.

Found it on your site, it is a bit difficult to navigate.
http://igohatsuyoron120.de/2015/0503.htm#q180v

Black has two more liberties, so he can connect tail when white reaches 5 liberties.

Life In 19x19

KataGo @ Igo Hatsuyoron 120

Re: KataGo @ Igo Hatsuyoron 120

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Re: KataGo @ Igo Hatsuyoron 120