5 1/3 points? - A Chen Yaoye / Park Younghun game

snorri · #1

From a GoGameGuru review by An Younggil 8p.

At move 207, the commentary reads that black's move is worth 5 1/3 points. Usually when I see deiri values quoted they are either whole points or in some cases to the half point. (That usually happens if the analysis includes a "half-point" ko that usually isn't a half a point.

) If I see this kind of fraction I wonder if someone has secretly been employing miai counting. But before I demand Youggil come out of the math closet, I'd like to hear what others think...

Click Here To Show Diagram Code: [go]$$B 5 1/3 points? $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . X O . X | $$ | . . . . O O . . . . . . . O O O O O X | $$ | . . O O X . O . . , O . O . O X X X . | $$ | . . O X . X O . . . O X O O X O X . X | $$ | . O . X . X X O . O X O X X X O O X . | $$ | . . X . X . O . O O X 1 . . . O . O X | $$ | . . . . . . X O . O X . . X X O X X . | $$ | . . X . . X . O . X . . . X O O X . X | $$ | . . X O X . . . . X . . . X X X O . . | $$ | . . O . O . . X O X O O O O X O O . . | $$ | . . O . O . O O X . . X X X O O X . . | $$ | . . . O O . O X X X X . . . . O X X X | $$ | . . . O . X X O O O O X X O O X O O X | $$ | . . O . . . . . X O . O X O X X O . O | $$ | . O O X X . X . X O O O . X X , X O . | $$ | O X X O X X . . X O . O X . X X X X . | $$ | . X O O O O X . X X O . O X O X . . . | $$ | . O . . X X . . . . . . . O O O . O . | $$ ---------------------------------------[/go]

Whole game record with commentary follows. It's a very exciting game---as white I think many of us would despair around move 79---but I recommend you read the article linked above.

snorri · #2

Also, in the same game, find a tesuji for black in the upper right after white 142:

Click Here To Show Diagram Code: [go]$$W $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . O O . . . . . . . O O . . O . | $$ | . . O O X . O . . , O . O . O X X X O | $$ | . . O X . X O . . . . X . O X O X . . | $$ | . O . X . X . . . O . . . X X O O X . | $$ | . . X . X . O . . 1 X . . . . O . . . | $$ | . . . . . . . . . O X . . X X O X X . | $$ | . . X . . X . O . . . . . . . O X . . | $$ | . . X O X . . . . X . . . X X X O . . | $$ | . . O . O . . X O X O O O O X O O . . | $$ | . . O . O . O O X . . X X X O O X . . | $$ | . . . O O . O X X X X . . . . O X X X | $$ | . . . O . X X O O O O X X O O X O O . | $$ | . . O . . . . . . . X O X . X X O . . | $$ | . . . , X . X . X O O O . X . O X O . | $$ | . . . O X . . . X O . . . . . X X X . | $$ | . . . O O . X . X X O . O . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Bill Spight · #3

I think that I can recreate An's calculations. And I disagree.

Click Here To Show Diagram Code: [go]$$Wc White first. $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . X O . X | $$ | . . . . O O . . . . C C C O O O O O X | $$ | . . O O X . O . . , O 5 O . O X X X . | $$ | . . O X . X O . . . O X O O X O X . X | $$ | . O . X . X X O . O X O X X X O O X . | $$ | . . X . X . O . O O X 1 3 8 . O . O X | $$ | . . . . . . X O . O X 2 4 X X O X X . | $$ | . . X . . X . O . X C C C X O O X . X | $$ | . . X O X . . . . X . . . X X X O . . | $$ | . . O . O . . X O X O O O O X O O . . | $$ | . . O . O . O O X . . X X X O O X . . | $$ | . . . O O . O X X X X . . . . O X X X | $$ | . . . O . X X O O O O X X O O X O O X | $$ | . . O . . . . . X O . O X O X X O . O | $$ | . O O X X . X . X O O O . X X , X O . | $$ | O X X O X X . . X O . O X . X X X X . | $$ | . X O O O O X . X X O . O X O X . . . | $$ | . O . . X X . . . . . . . O O O . O . | $$ ---------------------------------------[/go]

fills

If

extends, we get :w1:

-

. Later

is sente, forcing White to fill. For convenience I am counting the :ec:

points, three for each player. White scores the captured stone and the result is then -1, or 1 pt. for White.

Click Here To Show Diagram Code: [go]$$Bc Black first. $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . X O . X | $$ | . . . . O O . . . . C C C O O O O O X | $$ | . . O O X . O . . , O . O . O X X X . | $$ | . . O X . X O . . . O X O O X O X . X | $$ | . O . X . X X O . O X O X X X O O X . | $$ | . . X . X . O . O O X 1 C C . O . O X | $$ | . . . . . . X O . O X C C X X O X X . | $$ | . . X . . X . O . X . C C X O O X . X | $$ | . . X O X . . . . X . . . X X X O . . | $$ | . . O . O . . X O X O O O O X O O . . | $$ | . . O . O . O O X . . X X X O O X . . | $$ | . . . O O . O X X X X . . . . O X X X | $$ | . . . O . X X O O O O X X O O X O O X | $$ | . . O . . . . . X O . O X O X X O . O | $$ | . O O X X . X . X O O O . X X , X O . | $$ | O X X O X X . . X O . O X . X X X X . | $$ | . X O O O O X . X X O . O X O X . . . | $$ | . O . . X X . . . . . . . O O O . O . | $$ ---------------------------------------[/go]

is gote, of course. Now there is a gote left that gains 2/3 point.

Click Here To Show Diagram Code: [go]$$Wc Black first. Then White. $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . X O . X | $$ | . . . . O O . . . . C C C O O O O O X | $$ | . . O O X . O . . , O 1 O . O X X X . | $$ | . . O X . X O . . . O X O O X O X . X | $$ | . O . X . X X O . O X . X X X O O X . | $$ | . . X . X . O . O O X X C C . O . O X | $$ | . . . . . . X O . O X C C X X O X X . | $$ | . . X . . X . O . X . C C X O O X . X | $$ | . . X O X . . . . X . . . X X X O . . | $$ | . . O . O . . X O X O O O O X O O . . | $$ | . . O . O . O O X . . X X X O O X . . | $$ | . . . O O . O X X X X . . . . O X X X | $$ | . . . O . X X O O O O X X O O X O O X | $$ | . . O . . . . . X O . O X O X X O . O | $$ | . O O X X . X . X O O O . X X , X O . | $$ | O X X O X X . . X O . O X . X X X X . | $$ | . X O O O O X . X X O . O X O X . . . | $$ | . O . . X X . . . . . . . O O O . O . | $$ ---------------------------------------[/go]

If White plays next, we count 3 1/3 pts. for White, the three marked points plus 1/3 pt. in the ko. We count 7 pts. for Black, the six marked points plus 1 pt. for the captured White stone. The net count is 3 2/3 (for Black). Since the White play gained 2/3 pts., the count for the Black first diagram is 4 1/3.

The White first diagram has a count of -1, so the swing is 5 1/3 pts., as advertised.

I have claimed that the White response gained 2/3 of a pt. If so, the result if Black continued should be 5.

Click Here To Show Diagram Code: [go]$$Bc Black first. Then Black again. $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . X O . X | $$ | . . . . O O . . . . C 2 C O O O O O X | $$ | . . O O X . O . . , O 1 O . O X X X . | $$ | . . O X . X O . . . O X O O X O X . X | $$ | . O . X . X X O . O X 3 X X X O O X . | $$ | . . X . X . O . O O X X C C . O . O X | $$ | . . . . . . X O . O X C C X X O X X . | $$ | . . X . . X . O . X . C C X O O X . X | $$ | . . X O X . . . . X . . . X X X O . . | $$ | . . O . O . . X O X O O O O X O O . . | $$ | . . O . O . O O X . . X X X O O X . . | $$ | . . . O O . O X X X X . . . . O X X X | $$ | . . . O . X X O O O O X X O O X O O X | $$ | . . O . . . . . X O . O X O X X O . O | $$ | . O O X X . X . X O O O . X X , X O . | $$ | O X X O X X . . X O . O X . X X X X . | $$ | . X O O O O X . X X O . O X O X . . . | $$ | . O . . X X . . . . . . . O O O . O . | $$ ---------------------------------------[/go]

Black has 7 pts. as before, while White has 2 pts., for a net count of 5. Check.

So that is how I think that An got 5 1/3 pts. for the swing.

Why I disagree.

You may have noticed that the point for Black at L-11 disappeared when Black played first. That is because of a protective play. In the game Black made one by capturing a White stone at L-11 after a cut. In the White first diagram no protective play is needed because Black can atari that stone at L-10 instead of M-11, and the center Black stones are in no danger.

Click Here To Show Diagram Code: [go]$$Bc Protection needed? $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . X O . X | $$ | . . . . O O . . . . . . . O O O O O X | $$ | . . O O X . O . . , O c O . O X X X . | $$ | . . O X . X O . . . O X O O X O X . X | $$ | . O . X . X X O . O X O X X X O O X . | $$ | . . X . X . O . O O X 1 . . . O . O X | $$ | . . . . . . X O . O X . . X X O X X . | $$ | . . X . . X . O . X . . . X O O X . X | $$ | . . X O X . . . a X . . . X X X O . . | $$ | . . O . O . . X O X O O O O X O O . . | $$ | . . O . O . O O X . . X X X O O X . . | $$ | . . . O O . O X X X X . . . . O X X X | $$ | . . . O . X X O O O O X X O O X O O X | $$ | . . O . . . . . X O . O X O X X O . O | $$ | . O O X X . X . X O O O b X X , X O . | $$ | O X X O X X . . X O . O X . X X X X . | $$ | . X O O O O X . X X O . O X O X . . . | $$ | . O . . X X . . . . . . . O O O . O . | $$ ---------------------------------------[/go]

Even though a protective play was required in the actual game, it seems to me that four things had to occur besides the Black capture at :b1:

. White had to save the White stone at "a", preventing an eye for Black there. White had to cut at "b". White had to play atari at "c". And White had to take the resulting ko. To try to calculate the position taking all of that into account would take some time and effort. But I think that we can say that :b1:

gains around 3 pts., either as a gote or as a reverse sente.

5 1/3 points? - A Chen Yaoye / Park Younghun game

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