and 
each gain 2.5 pts. is correct, as it gives White a good follow-up, 
, which gains 2 pts. The temperature has dropped to 1 pt. Black to play and get the last play.This 'n' that
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Bill Spight
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Re: This 'n' that
Here is a problem based on the weiqitv commentary of the recent Wang Haoyang vs DeepZen game in MLily Cup. See https://www.lifein19x19.com/forum/viewt ... 86#p220886 .
and each gain 2.5 pts. is correct, as it gives White a good follow-up, , which gains 2 pts. The temperature has dropped to 1 pt. Black to play and get the last play.
and each gain 2.5 pts. is correct, as it gives White a good follow-up, , which gains 2 pts. The temperature has dropped to 1 pt. Black to play and get the last play.The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
Here is the actual game from a similar position.
Earlier in the game (B 215), Black made the exchange,
- 
, which was a losing sente that sacrificed 3/4 pt. Peng Quan, the commentator, thought that that was the losing move. B 231 sacrifices an additional 1/6 pt. to get B 233, which gains 2 pts. Despite the fact that White plays first at temperature 1, Black can get the last play. So it turns out that B 233 is the last effective play of the game. Gaining 2 pts. with the last play may well justify B 215. 
White took his 1 pt. sente, and then both players erred. W 238 is a mistake, as was B 239.
In this position, Black to play and win.
Edit: Sorry, White can still win. I made a miscalculation.
Earlier in the game (B 215), Black made the exchange,
- , which was a losing sente that sacrificed 3/4 pt. Peng Quan, the commentator, thought that that was the losing move. B 231 sacrifices an additional 1/6 pt. to get B 233, which gains 2 pts. Despite the fact that White plays first at temperature 1, Black can get the last play. So it turns out that B 233 is the last effective play of the game. Gaining 2 pts. with the last play may well justify B 215. White took his 1 pt. sente, and then both players erred. W 238 is a mistake, as was B 239.
In this position, Black to play and win.
Edit: Sorry, White can still win. I made a miscalculation.
Last edited by Bill Spight on Fri Aug 25, 2017 3:50 pm, edited 3 times in total.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Schachus
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Re: This 'n' that
Maybe I'm wrong, but:
So my answer is
Edit:
Of coarse what I wrote is for japanese rules, in chinese, this might change
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Bill Spight
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Re: This 'n' that
Since there are no ko fights to speak of, nor seki, correct play by Japanese rules is correct by Chinese rules.Schachus wrote:Maybe I'm wrong, but:
So my answer isEdit:Of coarse what I wrote is for japanese rules, in chinese, this might change
In reply to your edit:
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
Schachus wrote:
Last edited by Bill Spight on Fri Aug 25, 2017 3:52 pm, edited 1 time in total.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
Apologies to all for the claim that Wang and Zen both erred. I miscounted, I am afraid.
Boy! First I don't check whether Black got the last play, just assuming that weiqitv was right, and then I miscount results. Boy is my face red!
Boy! First I don't check whether Black got the last play, just assuming that weiqitv was right, and then I miscount results. Boy is my face red!
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
OK. Well, to redeem myself a bit, here is the answer to the first question. Black to play and get the last play.
There is more than one answer, but this is the most accurate way.
After
White takes his sente and then there are a few variations for 
.
takes one stone. Then Black simply takes the hane-and-connect, leaving "a" and "b" miai.
If White takes the hane-and-connect,
is sente. If Black now gets to play at 10, White will have to make a protective play at "a". 
is the last play.
If, 
gets the last play, leaving "a" and the hane-and-connect as miai.
If, is sente because of the threat to take away the point at "a". After 
Black takes the hane-and-connect to get the last play.
Failure Diagram
looks plausible, as it sets up the eventual threat to force a protective play. However, after White takes his sente, he plays , which leaves two hane-and-connects on the board and gets the last play.
Taking the hane-and connect on the right also fails, for the same reason.
Curiously, playing a reverse sente works, because Black can get the last play, even if White plays first. That's the subject of my next note.
There is more than one answer, but this is the most accurate way.
After
White takes his sente and then there are a few variations for . takes one stone. Then Black simply takes the hane-and-connect, leaving "a" and "b" miai.If White takes the hane-and-connect,
is sente. If Black now gets to play at 10, White will have to make a protective play at "a". is the last play.If
, gets the last play, leaving "a" and the hane-and-connect as miai.If
, is sente because of the threat to take away the point at "a". After Black takes the hane-and-connect to get the last play.Failure Diagram
looks plausible, as it sets up the eventual threat to force a protective play. However, after White takes his sente, he plays , which leaves two hane-and-connects on the board and gets the last play.Taking the hane-and connect on the right also fails, for the same reason.
Curiously, playing a reverse sente works, because Black can get the last play, even if White plays first. That's the subject of my next note.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
Back to the actual game. Here is play at temperature 1.
White starts by taking his sente, and then plays the kosumi, White 238. Black replies with Black 239. For quite a while I thought that both of these moves were mistakes, but that was because of miscounting. White 240 was a good play. If White plays there and at "a", Black will need a protective play at "b". But then Black 241 makes miai of "a" and the hane-and-connect on the right side, and gets the last play.
Even though they were not mistakes, I still think that White 238 and Black 239 were not good technique in a fight for the last play. Why?
gives Black extra chances to get the last play after Black plays . Any of "a", "b", or "c" might be the last play of the game, thanks to . See details below.
But Zen turns right around and gives those extra chances back, with interest. After, White will get the last local play at "a", regardless of who goes first. The next diagram shows technically better play for Black.
makes 
sente, because if White then allows Black to play at 5, White must make a protective play at "a". So 
is not the last play. Next, Black takes the hane-and-connect and then gets the last play with 
.
So what is technically correct play for White?
I think that there are two candidates. The first one is to take the stone with . That simplifies the play, but Black has to thread the needle.
The second one is the hane-and-connect. It leaves a more complicated position for Black to solve.
Edit: Actually, the hane-and-connect is not technically correct. The abutment at L-18 is, as well as the capture of the Black stone. But abutment gives Black no chance to go wrong.
You may wish to figure out how Black gets the last play in each of these positions.
White starts by taking his sente, and then plays the kosumi, White 238. Black replies with Black 239. For quite a while I thought that both of these moves were mistakes, but that was because of miscounting.
White 240 was a good play. If White plays there and at "a", Black will need a protective play at "b". But then Black 241 makes miai of "a" and the hane-and-connect on the right side, and gets the last play. Even though they were not mistakes, I still think that White 238 and Black 239 were not good technique in a fight for the last play. Why?
gives Black extra chances to get the last play after Black plays . Any of "a", "b", or "c" might be the last play of the game, thanks to . See details below.But Zen turns right around and gives those extra chances back, with interest. After
, White will get the last local play at "a", regardless of who goes first. The next diagram shows technically better play for Black. makes sente, because if White then allows Black to play at 5, White must make a protective play at "a". So is not the last play. Next, Black takes the hane-and-connect and then gets the last play with . So what is technically correct play for White?
I think that there are two candidates. The first one is to take the
stone with . That simplifies the play, but Black has to thread the needle.The second one is the hane-and-connect. It leaves a more complicated position for Black to solve.
Edit: Actually, the hane-and-connect is not technically correct. The abutment at L-18 is, as well as the capture of the Black stone. But abutment gives Black no chance to go wrong.
You may wish to figure out how Black gets the last play in each of these positions.
Last edited by Bill Spight on Tue Aug 29, 2017 7:49 am, edited 1 time in total.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
Actually, the hane-and-connect is not technically correct. 
We can show that with a difference game.
We set up the difference game by setting up the mirror position and then giving White one play in one position and Black the other play in the mirror position. (The middle becomes no man's land, OC.) Is either player better off after the exchange?)
First question: Can Black to play win?
is an interesting play. If 
mirrors, the board may look like miai, but 
is sente. White must play 
to prevent having to make a protective play at "a", and 
gets the last play to win by 1 pt.
If Black gets the sente, he obviously wins, so let prevent it. Now Black leaves the two hane-and-connects as miai and plays on the bottom to get the last play and win.
Second question: Can White to play win? If not, Black's play, capturing the single stone, is technically superior to the hane-and-connect.
OC, one way to prevent is to play . But then makes both the top and bottom miai and gets jigo.
is a clever play. Now if , White can play , which leaves the two hane-and-connects miai, as well as "a" and "b". White wins. Similarly, if Black plays at 3, White replies at 2, and wins.
So Black responds with. Now if White plays at "a" to make 3 and 4 miai, Black plays the hane-and-connect at "b" to get a mirror position and jigo. So to protect the point at "a" White blocks with , but then leaves "a" and "b" miai and gets jigo.
is another potential answer to Black's threat on the top. But then gives Black the last play in the top corridor. After , forces to protect "a". Then Black gets 
for jigo.
Capturing the single stone is technically superior to the hane-and-connect.
We can show that with a difference game.We set up the difference game by setting up the mirror position and then giving White one play in one position and Black the other play in the mirror position. (The middle becomes no man's land, OC.) Is either player better off after the exchange?)
First question: Can Black to play win?
is an interesting play. If mirrors, the board may look like miai, but is sente. White must play to prevent having to make a protective play at "a", and gets the last play to win by 1 pt.If Black gets the sente, he obviously wins, so let
prevent it. Now Black leaves the two hane-and-connects as miai and plays on the bottom to get the last play and win.Second question: Can White to play win? If not, Black's play, capturing the single stone, is technically superior to the hane-and-connect.
OC, one way to prevent
is to play . But then makes both the top and bottom miai and gets jigo. is a clever play. Now if , White can play , which leaves the two hane-and-connects miai, as well as "a" and "b". White wins. Similarly, if Black plays at 3, White replies at 2, and wins.So Black responds with
. Now if White plays at "a" to make 3 and 4 miai, Black plays the hane-and-connect at "b" to get a mirror position and jigo. So to protect the point at "a" White blocks with , but then leaves "a" and "b" miai and gets jigo. is another potential answer to Black's threat on the top. But then gives Black the last play in the top corridor. After , forces to protect "a". Then Black gets for jigo.Capturing the single stone is technically superior to the hane-and-connect.
Last edited by Bill Spight on Thu Oct 29, 2020 1:01 am, edited 3 times in total.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
Earlier I said that the kosumi in the actual game was not technically correct. We can show that with a difference game, too.
Note that the two hane-and-connects are miai, so we can ignore them in the play.
First question: Can Black to play win?
@ "a"
Yes, Black to play wins. is, as we know, the key play to separate the White groups and make sente. White offers the most stubborn resistance. After Black has only one play to win. is sente, but Black gets the last play on the bottom side. Note that is good after Black has united his groups.
prevents Black from playing there later, but Black wins easily.
After Black takes her sente with and then switches to the hane-and-connect on the bottom side. Finally, gets the last play.
Question 2: Can White to play win?
sets a trap. If is sente, because of a possible ko in the corner. Then settles the bottom side, and 
gets the last play. If each player wins the difference game by playing first, we cannot say that either play is technically superior to the other.
is the defense to get jigo. If , makes miai of the capture of the stone on the top side and the hane-and-connect on the bottom side. 
gets the last play and jigo.
If takes the Black stone, is sente. Then gets the last play on the bottom side, for jigo.
The capture is technically superior to the kosumi, as well.
----
BTW, there is another White play that is not technically inferior to the capture, and that is the play on the second line. As we can see with the following difference game.
The top side is miai, so whoever plays first can win with the kosumi at "a".
Note that the two hane-and-connects are miai, so we can ignore them in the play.
First question: Can Black to play win?
@ "a"Yes, Black to play wins.
is, as we know, the key play to separate the White groups and make sente. White offers the most stubborn resistance. After Black has only one play to win. is sente, but Black gets the last play on the bottom side. Note that is good after Black has united his groups. prevents Black from playing there later, but Black wins easily.After
Black takes her sente with and then switches to the hane-and-connect on the bottom side. Finally, gets the last play.Question 2: Can White to play win?
sets a trap. If is sente, because of a possible ko in the corner. Then settles the bottom side, and gets the last play. If each player wins the difference game by playing first, we cannot say that either play is technically superior to the other. is the defense to get jigo. If , makes miai of the capture of the stone on the top side and the hane-and-connect on the bottom side. gets the last play and jigo.If
takes the Black stone, is sente. Then gets the last play on the bottom side, for jigo.The capture is technically superior to the kosumi, as well.
----
BTW, there is another White play that is not technically inferior to the capture, and that is the play on the second line. As we can see with the following difference game.
The top side is miai, so whoever plays first can win with the kosumi at "a".
Last edited by Bill Spight on Wed Sep 13, 2017 2:36 pm, edited 1 time in total.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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EdLee
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Schachus
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Re: This 'n' that
I'm guessing Bill did. that on purpose, to make it clear that this is not one board with a center but two seperate positions.
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Bill Spight
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Re: This 'n' that
Right.Schachus wrote:I'm guessing Bill did. that on purpose, to make it clear that this is not one board with a center but two seperate positions.
At least, nobody can say, What about a play on tengen? 
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
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Bill Spight
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Re: This 'n' that
The Four Immortals game: A corrupted game record
A relay game by four immortals (Taoist immortals, I suppose) is game number 5 in the Carefree and Innocent Pastime Collection(C&IP), played in 1094. The game record is available in the GOGOD database. There are problems with the game record in the C&IP. In "The history of go rules" (2011) Chen Zuyuan notes that the statement that the game was 242 moves long was written in with a brush later. (The book was printed.) It would have been usual to say that each side made 121 moves, and elsewhere it is stated that in this game each side made 125 moves. Chen speculates about all this. But there is another problem with the game record, as the final diagram shows.
White 242 was a protective play. Now the book states that White has 9 Black prisoners and has 43 points, and that Black has 7 White prisoners and has 42 points. To get those scores you first make all the protective plays and then fill in the territories with the prisoners, and then subtract the group tax. White has four groups and Black has two, so White's group tax is 8 pts. and Black's group tax is 4 pts. Without the group tax White would win by 5 pts.
So far, so good, except that to get a score of 43 pts. White has to count the tengen point (marked), and White cannot do that without having a White stone at "a". The game is not really over, and, unless the four immortals were very bad players, the game record is corrupted.
Gotta run now, but I will speculate on what went wrong, later.
A relay game by four immortals (Taoist immortals, I suppose) is game number 5 in the Carefree and Innocent Pastime Collection(C&IP), played in 1094. The game record is available in the GOGOD database. There are problems with the game record in the C&IP. In "The history of go rules" (2011) Chen Zuyuan notes that the statement that the game was 242 moves long was written in with a brush later. (The book was printed.) It would have been usual to say that each side made 121 moves, and elsewhere it is stated that in this game each side made 125 moves. Chen speculates about all this. But there is another problem with the game record, as the final diagram shows.
White 242 was a protective play. Now the book states that White has 9 Black prisoners and has 43 points, and that Black has 7 White prisoners and has 42 points. To get those scores you first make all the protective plays and then fill in the territories with the prisoners, and then subtract the group tax. White has four groups and Black has two, so White's group tax is 8 pts. and Black's group tax is 4 pts. Without the group tax White would win by 5 pts.
So far, so good, except that to get a score of 43 pts. White has to count the tengen point (marked), and White cannot do that without having a White stone at "a". The game is not really over, and, unless the four immortals were very bad players, the game record is corrupted.
Gotta run now, but I will speculate on what went wrong, later.
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.
At some point, doesn't thinking have to go on?
— Winona Adkins
Visualize whirled peas.
Everything with love. Stay safe.