Life In 19x19

daal wrote:Sad to say, but I am not even sure what is meant by "sente." How does this sound for a definition to fit my purposes: "a sente move is a move whose followup is bigger than any other move on the board, so it will presumably be answered."

That is one definition, but for calculating sizes we stick to local sente. I have posted a good bit here on sente vs. gote.

Bill wrote:Start with the rough value of positions.

So you mean: imagine black playing there first to the bitter end, compare white and black territory, imagine white playing there first to the bitter end, compare white and black territory. The difference between these two values is the value of the position?

The value of the position lies between those two values.

$$B Black goes first
$$ +-------------------+
$$ | M M M M X X O T T |
$$ | M M M M X O O T T |
$$ | . . , X B O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +-------------------+

Click Here To Show Diagram Code

[go]$$B Black goes first
$$ +-------------------+
$$ | M M M M X X O T T |
$$ | M M M M X O O T T |
$$ | . . , X B O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +-------------------+[/go]

$$B White goes first
$$ +-------------------+
$$ | M M X O O T T T T |
$$ | M M X X O T T T T |
$$ | . . , X W O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +-------------------+

Click Here To Show Diagram Code

[go]$$B White goes first
$$ +-------------------+
$$ | M M X O O T T T T |
$$ | M M X X O T T T T |
$$ | . . , X W O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +-------------------+[/go]

So are you saying that the value of the position is 8? I'll stop here, because I think that that is not what you mean.

I edited the diagrams to show the bitter end. The value of the position lies between 4 and -4, both values from Black's point of view.

Tami wrote:

Bill Spight wrote:

Position "a" is a big gote, and the value is around 0, by symmetry. It may be worth a bit for Black, because of the flaws in the White position in the top right. But 0 is a good ball park figure.

I'm struggling with this...surely getting to play at a is worth quite a bit (12-14 points)?

That's looks like a pretty good ballpark figure. Miai (Absolute™) counting, OC.

Or do you mean that when estimating the score, position a has to be reckoned as 0 because that's the average of White and Black playing there?

Just eyeballing it, it's pretty symmetrical, eh?

In fact, this is my current stumbling block with O's book. I'm quite happy to follow his reasoning about the value of a local position being counted as the average of a black or white play there, but I put it aside for the time being when I came to the section concerning the value of actual moves.

The value of a play depends upon the difference in value between two positions. The value of positions is basic.

Bill Spight wrote: I edited the diagrams to show the bitter end. The value of the position lies between 4 and -4, both values from Black's point of view.

Ok, the value of that position is 0. So what does the value of the position tell us about whether to move there or not? Does it make sense to compare it to the value of another position, for example this one:

Click Here To Show Diagram Code

[go]$$B black first
$$ +-------------------+
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . , X . O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | T T T T X O M O M |
$$ | T T T X O O M M M |
$$ +-------------------+[/go]

Click Here To Show Diagram Code

[go]$$B white first
$$ +-------------------+
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . , X . O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | T X X . . O M O M |
$$ | T X O O O C M M M |
$$ +-------------------+[/go]

Here we have +2 if black goes first and -3.5 if white goes first. Aack, a fraction! (Prolly wrong anyway). Any further fractions no longer qualify as easy! So lets just say that the middle is less than 0 and more than -1, which is different from the 0 that we get from the position at the top. What does that tell us about where to move?

daal wrote:

Bill Spight wrote: I edited the diagrams to show the bitter end. The value of the position lies between 4 and -4, both values from Black's point of view.

Ok, the value of that position is 0. So what does the value of the position tell us about whether to move there or not? Does it make sense to compare it to the value of another position, for example this one:

Not that one, but this one.

Click Here To Show Diagram Code

[go]$$B After White plays gote
$$ +-------------------+
$$ | . . . . . . . . . |
$$ | . . . . W . . . . |
$$ | . . , X . O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +-------------------+[/go]

Playing in the top left, because the three moves (a, b, and c) and positions are assumed to be independent (even if that's not quite right).

For instance, let's guess that this position is a White sente.

Click Here To Show Diagram Code

[go]$$W White sente
$$ +-------------------+
$$ | . . . 3 . C C C C |
$$ | 6 5 1 2 W . C C C |
$$ | . 4 7 X . O C C C |
$$ | S 8 . X . O C C C |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +-------------------+[/go]

Then we can make a ball park estimate that this position is worth 12 pts. to White. That means that we can estimate that has gained 12 pts. Like Tami said.

It's better to make a hanging connection after the hane:

$$B
$$ +-------------------+
$$ | . . . 3 9 5 7 8 . |
$$ | . . . . 1 2 6 0 . |
$$ | . . , X . O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +-------------------+

Click Here To Show Diagram Code

[go]$$B
$$ +-------------------+
$$ | . . . 3 9 5 7 8 . |
$$ | . . . . 1 2 6 0 . |
$$ | . . , X . O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +-------------------+[/go]

Assuming the other player doesn't want to risk the ko, then you get more points.

Hmm... something seems off ?
And tenuki (above variation) causes different calculations.

Click Here To Show Diagram Code

[go]$$B var 2
$$ +--------------------
$$ | . . . . 5 3 4 . . |
$$ | . . . . 1 2 6 . . |
$$ | . . , X . O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +--------------------[/go]

If simply replies with descend, then locally B has fewer points than B's hane & solid connect in var 2.

Click Here To Show Diagram Code

[go]$$B var 3
$$ +--------------------
$$ | . . . 3 . 4 . . . |
$$ | . . . . 1 2 . . . |
$$ | . . , X . O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +--------------------[/go]

This tiger's mouth is after hane, but leads to yet different calculations
( but locally B still seems worse off than var 2 ):

Click Here To Show Diagram Code

[go]$$B var 4
$$ +--------------------
$$ | . . . 5 6 3 4 . . |
$$ | . . . . 1 2 . . . |
$$ | . . , X . O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +--------------------[/go]

Bill Spight wrote:

daal wrote:

Bill Spight wrote: I edited the diagrams to show the bitter end. The value of the position lies between 4 and -4, both values from Black's point of view.

Ok, the value of that position is 0. So what does the value of the position tell us about whether to move there or not? Does it make sense to compare it to the value of another position, for example this one:

Not that one, but this one.

$$B After White plays gote
$$ +-------------------+
$$ | . . . . . . . . . |
$$ | . . . . W . . . . |
$$ | . . , X . O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +-------------------+

Click Here To Show Diagram Code

[go]$$B After White plays gote
$$ +-------------------+
$$ | . . . . . . . . . |
$$ | . . . . W . . . . |
$$ | . . , X . O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +-------------------+[/go]

Playing in the top left, because the three moves (a, b, and c) and positions are assumed to be independent (even if that's not quite right).

For instance, let's guess that this position is a White sente.

$$W White sente
$$ +-------------------+
$$ | . . . 3 . C C C C |
$$ | 6 5 1 2 W . C C C |
$$ | . 4 7 X . O C C C |
$$ | S 8 . X . O C C C |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +-------------------+

Click Here To Show Diagram Code

[go]$$W White sente
$$ +-------------------+
$$ | . . . 3 . C C C C |
$$ | 6 5 1 2 W . C C C |
$$ | . 4 7 X . O C C C |
$$ | S 8 . X . O C C C |
$$ | . . X . , . O . . |
$$ | . . . . X . . . . |
$$ | . . , X . . , . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +-------------------+[/go]

Then we can make a ball park estimate that this position is worth 12 pts. to White. That means that we can estimate that has gained 12 pts. Like Tami said.

Ok. So you are saying that the value of a position gives us a reference from which to judge changes in that position. Right? In the above example are you showing how one determines a value for a move at a in order to be able to compare it to other moves such as b or c, Right? If so, I don't get it. Don't we have to assume that black answers the move at a?

daal wrote:Ok. So you are saying that the value of a position gives us a reference from which to judge changes in that position. Right? In the above example are you showing how one determines a value for a move at a in order to be able to compare it to other moves such as b or c, Right?

Yes, as long as you realize that the biggest move is not always best.

If so, I don't get it. Don't we have to assume that black answers the move at a?

If so, don't you also have to assume that White answers Black's move at a? In that case, a move at a is a free lunch. You don't have to compare it to anything, just play it.

Or maybe you think you have to compare it to other plays to decide whether to answer it or not. In that case, you can't assume that it is a free lunch.

I get that it's a free lunch. If it is sente for both, just play it. That makes sense. What I don't see is what the diagram means where you say that w gets 12 points. Since we are assuming a play at a is sente, why would that diagram take place? Wouldn't black just answer a?

daal wrote:I get that it's a free lunch. If it is sente for both, just play it. That makes sense. What I don't see is what the diagram means where you say that w gets 12 points. Since we are assuming a play at a is sente, why would that diagram take place? Wouldn't black just answer a?

You're assuming that it is a free lunch, I'm not.

Click Here To Show Diagram Code

[go]$$Bcm11 White to play
$$ +-------------------+
$$ | . . . . . . . . . |
$$ | . . . . 1 . . . . |
$$ | . . , X . O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . X . O . . . |
$$ | . . , X . O , . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ +-------------------+[/go]

TANSTAAFL

For understanding some basics of evaluation, starting with one local endgame that is a whole board (life and death) problem is maybe not the simplest:)

a whole board (life and death) problem...

daal, Robert,

Does it help (a bit) if we remove L&D concerns... ?

Click Here To Show Diagram Code

[go]$$Wc (ignoring dimmed area)
$$ -------------------------
$$ | ? ? ? . . . . . . . . |
$$ | ? ? ? . . . a . . . . |
$$ | ? ? ? . . X . O , . . |
$$ | ? ? ? . . X . O . . . |
$$ | ? ? ? . . X . O . . . |
$$ | ? ? ? . . X . O . . . |
$$ | ? ? ? . . . . . O . . |
$$ | ? ? ? . . . X . b . . |
$$ | ? ? ? . . X . . , . . |
$$ | ? ? ? . . . c O . O . |
$$ | ? ? ? . . . . . . . . |
$$ -------------------------[/go]

Click Here To Show Diagram Code

[go]$$B
$$ +-------------------+
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | . . , X . O , . . |
$$ | . . . X . O . . . |
$$ | . . X . , . O . . |
$$ | . . . . X . 1 . . |
$$ | . . , X . . 2 . . |
$$ | . . . . . O . O . |
$$ | . . . . . . . . . |
$$ +-------------------+[/go]

A minimum amount of tactical reading is also necessary.

Alright, I give up. it was a stupid question.

We are told that there are no stupid questions but maybe too optimistic expectations.

Basic endgame theory can be value-less but as soon as we always want to compare different moves well, move values and other values come in. If they shall be meaningful by comparing well, calculation and comparison of numbers cannot be avoided.

There have been attempts of simplifying that: no follow-ups, only one follow-up move, no fractions, only occasional trivial fractions, rounding, only positive numbers, no arithmic operation, only addition, only gote, deemphasised sente etc. All such simplifications have quickly led to insufficient scope of application or frequent mistakes in evaluation.

Some kinds of simplifications can make sense if used so that they do make sense: rounding if the rounding error does not cause wrong comparisons, stopped deeper iterative analysis of follow-ups if such rounding is guaranteed, considering an ensemble of moves with large values and replacing all smaller moves by some environment model, ignoring the last move before the microendgame etc.

Traditional endgame theory has the simplification of initially avoiding calibration of move values and the complication of initially possibly having uncomparable move values. Modern endgame theory has the complication of immediately calibrating move values and the simplification of already having comparable move values.

There is no such thing as consistently good endgame without effort of value calculation and comparison. Quite like there is no consistently good life and death without effort of tactical reading, no consistently good positional judgement without effort of counting and analysis etc.

The endgame affects circa half of the moves so why would you expect to play good endgame if spending less than half of your go study on it? You play a scored game but expect to succeed without calculating numbers? Fight for your life and you find yourself in counting liberties instead of endgame values. However, good fighting for resignation relies on assessing its necessity by good positional judgement and predicted endgame in the case of a peacefully continued game.

Learn to love calculations!

Tami wrote:

daal wrote: You said you will not have time to calculate during a game. I guess the usual thing is to calculate examples outside your games, and by that train your intuition to better and better guess the values quickly during a game. It's like with tsumego. The more you do them the better you get at guessing how to kill or live in a fast game. I wouldn't mind doing this, if there were a list of 10 common positions and their values, but there doesn't seem to be such a list, so I wouldn't know where to start.

There is the Nihon Kiin Yose Small Dictionary. ISBN 978-4-8182-0437. There is a section giving values for typical endgame plays. It has a lot of other good things, too, and you only need minimal Japanese to get the gist of it.

Just don't trust it about the free lunch (double sente). It's whole board example with several so-called double sente is just wrong.

Also, check out the Sensei's Library miai value lists, as light vector said.