Usually black defends one of the cuts afterwards, yes, but Bill said the position needed to have an even number of moves. Had I fixed one of the cuts that would again create a position where white has sente.


Considering the board position, it is likely that every good white move will be sente. White is working to invade and/or reduce. Black is simply trying to defend his moyo. Playing a gote move for white would make the board position very sad indeed as black will get to solidify more.

Beyond that problem, I don't see why I need to have white play a gote move in order to evaluate a board position. Are you not supposed to take who has sente into account when evaluating the board? It is not like both diagrams are black to play.

If you are saying that to evaluate the board you need an even number of stones then apparently a lot of go books get this wrong. I have seen countless diagrams where white has sente.

Or are you saying that you simply need it when trying to compare two board positions? If so, Kato Masao made a mistake in "The Chinese Opening" by comparing these two joseki:

Click Here To Show Diagram Code

[go]$$c Described as a failure
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . 7 5 4 6 . . |
$$ | . . . . . . . . . . . X . O . 1 O . . |
$$ | . . . O . . . . . , . . . . . X 2 . . |
$$ | . . . . . . . . . . . . . . . 3 . . . |
$$ | . . . . . . . . . . . . . . . . 8 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Click Here To Show Diagram Code

[go]$$c Described as correct
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . 4 . . . . . |
$$ | . . . . . . . . . . . X . O . 2 O . . |
$$ | . . . O . . . . . , . . . . 3 X 1 . . |
$$ | . . . . . . . . . . . . 5 . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

_________________
"You have to walk before you can run. Black 1 was a walking move.
I blushed inwardly to recall the ignorant thoughts that had gone through
my mind before, when I had not realized the true worth of Black 1."
-Kageyama Toshiro on proper moves

It is true that you can get extended sente sequences in go. But generally speaking the size of plays declines gradually, which means that good gote are normally available. In this case, the very fact that there was no standout play for White suggests that most plays under consideration carry no great threat. Besides, while Black has a large sphere of influence, it is not a moyo.



No, it is not necessary. But if such evaluation were possible we would not be having this discussion.



Sure. We assume that sente are played and responded to.



What I am saying is that when you do not have a precise evaluation function, but are relying upon judgement, comparing positions where different players got the last move is difficult, as a rule. Because you do not have an estimate for the difference in moves.



I am sure that Kato would not have had any trouble adding a Black gote to Diagram 1, and then be able to say, "Even if Black plays here, this is not as good for Black as Diagram 2."

Besides, Kato could have been wrong, you know.

Edit: Let me go into that possibility a little more.

If we are talking about judgement, then Kato's was better than anybody's here. But because of the different parity of the moves, we are also talking about the value of a play. Black has made an extra play in Diagram 2. There is a traditional value for an early play that is demonstrably too low, 10 points. We are reasonably certain that that is too low because it implies a komi of 5 points. People who have studied the statistics of go have known for four decades that a komi of 7 points is better, and maybe komi should be higher than that. But that does not mean that the pros have known that. In fact, Ishida's book about the value of plays is obviously based upon traditional values. Since Japanese komi went up to 6.5, maybe Japanese pros now believe that early moves are worth more. But Kato wrote his book before that, when komi was 5.5, and the value of 10 was consistent with that.

I am not claiming that Kato made a numerical calculation, but suppose that if you made him guess, he would say that Diagram 2 was worth around 15 pts. more for Black than Diagram 1. (I have an evaluation function that says just that. Not that I can claim that the function is correct. ) Then, since 15 is greater than 10, the assumed value of the extra play, Diagram 2 is preferable for Black. But what if the true value of the extra play is 14 or 15 points? Then there is not much to choose between the two diagrams, is there? (BTW, my evaluation function tends to overvalue outside influence, and may well be overvaluing Diagram 2. Then Diagram 1 would be preferable, wouldn't it? )

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

Visualize whirled peas.

Everything with love. Stay safe.

Thanks everyone for all the comments! Very interesting stuff. I always find it hard to make a judgement about large moyos. I tend to overestimate them, and that feeling led to me playing the move in the game.

@ez4u :
Of course I didn't really think I had found some insane tesuji . I knew it was most probably a nonsense move, but it looked interesting, so I played it on the spur of the moment.
I just wanted to know if it was THAT bad or if there was some hope .

Is it difficult to come up with a "reasonable" board where the UL corner broken shape is acceptable for W ?
( It's easy to come up with a contrived one: for example,
W is already way ahead the rest of the board,
so W could easily win even with a move like .)

Click Here To Show Diagram Code

[go]$$
$$ -----------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . O . . . . . . . . . . . . . . |
$$ | . . . , 3 1 . . . , . . . . . , . . . |
$$ | . . . . . 2 . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]

No, using Kombilo. Found a few pro games, they seem to be when the shoulder hit is a jump from a big weak group and if they do the broken shape you lean and will kill the weak group. See move 71.

Thanks, Uberdude.

But White did not create a broken shape. Seems to me that somebody found a pro game not too long ago with an immediate attachment leading to a broken shape. IIRC, Kato was the one to make the attachment.

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

Visualize whirled peas.

Everything with love. Stay safe.

My point was really that the 'ploy' was more than a single move. It included the follow up. The desire to limit the center at the expense of the corner was reasonable (best or not is obviously a long discussion ). You will almost certainly never face exactly that position again, so a too detailed analysis of it will be less useful than recognizing the general characteristics of what you played.

_________________
Dave Sigaty
"Short-lived are both the praiser and the praised, and rememberer and the remembered..."
- Marcus Aurelius; Meditations, VIII 21

Perhaps because my rank is around Vincent's, I think I share his original apprehensions.

I often think "If white gets three big corners, white is doing well", however this feels like going along with black's plan (as noted, black must be comfortable with an influence game).

_________________
Revisiting Go - Study Journal
My Programming Blog - About the evolution of my go bot.