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 Post subject: How to tell if a play or position is sente
Post #1 Posted: Fri Dec 05, 2014 10:14 pm 
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How to tell if a play or position is sente

At some point, beginners get the idea that if the opponent answers a play, that play is sente, and if not, then it is gote. That is one meaning of sente. Note that there is an implicit assumption of locality, since globally, every play but the last (with rare exceptions) is answered.

But after a while it becomes apparent that that idea is unsatisfactory. If Black answers a White play, maybe that is because Black made a mistake, not because the play itself was sente. Black should have played somewhere else. Black’s reply then says more about the player than about the play. That realization leads to a second meaning of sente, as a play that the opponent should answer, whether he actually does or not. As for plays that are answered, we say that they are played with sente, not necessarily that they are sente.

Now we can classify local positions as

1) gote, where the best play by each player is gote;

2) sente, where the best play by one player is sente, while the best play by the opponent is gote; (We call the opponent’s play a reverse sente.)

3) double sente, where the best play by each player is sente.

Obviously, in a double sente position where playing sente gains points by comparison with allowing the opponent to play sente, we should play the double sente immediately -- or soon, anyway. There is even a go proverb that tells us to play double sente early.

These definitions are perfectly sensible. However, whether a position is gote, sente, or double sente still depends upon the rest of the board. How can we tell whether another play is better or worse than a local reply? OC, if we can read the board out, there is no problem. But typically we cannot read the whole go board out. One heuristic that we can use is the size of a play, how much it gains. If the local reply gains more than any other play, it is probably the right play, and the opponent's play is sente. The question then arises of how much a play gains. We’ll get to that question soon. :)

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Last edited by Bill Spight on Fri Dec 05, 2014 10:27 pm, edited 1 time in total.
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 Post subject: Re: How to tell if a play or position is sente
Post #2 Posted: Fri Dec 05, 2014 10:25 pm 
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But still there are local positions that seem to be inherently gote or sente. Let’s take a look at a couple of them.

Edit: The diagrams follow the standard convention that the framing stones are immortal.

Click Here To Show Diagram Code
[go]$$ Diagram 1 Gote
$$ -------------------
$$ . . O O a O X . . .
$$ . . O X X O X X . .
$$ . . O O X O O X . .
$$ . . . . X X X X . .
$$ . . . . . . . . . .
$$ . . . . . . . . . .[/go]


The position in Diagram 1 is clearly gote, where either player will play at "a", because the opponent either cannot reply or will not reply. That one is easy.

Click Here To Show Diagram Code
[go]$$W Diagram 2 Sente
$$ -------------------
$$ . . O 1 . O X . . .
$$ . . O X X O X X . .
$$ . . O O X O O X . .
$$ . . . . X X X X . .
$$ . . . . . . . . . .
$$ . . . . . . . . . .[/go]


The position in Diagram 2 certainly looks like sente. :w1: carries a large threat, larger than it appears to gain. (I say appears to gain because we do not yet know how much it gains.)

It turns out that how much a play or sequence of play gains will distinguish sente from gote. How do we determine how much a play or sequence of play gains? It is the difference between the value of the original position before the play or sequence and the value of the final position after the play or sequence.

Let’s figure out the value of the gote position in Diagram 1 and how much a play gains. If White plays first the resulting value is 0. If Black plays first the resulting value is 8 points for Black. The value of the original position is the average value, or 4 points for Black, and a play by either player gains 4 points. (I assume that this is all familiar. :))

Now let’s figure out the value of the position in Diagram 2, as though it were gote. After :w1: the value of the resulting position is 4 points (for Black understood), and after :b1: the value of the resulting position is 9 points. The average value is 6.5, (Edit: which we take to be the value of the original position), and the value of a play, assuming that it is gote, is 2.5 points. In that case, :w1: would gain 2.5 points and a Black reply would gain 4 points. Since Black would gain more than White in this exchange, Black would reply. So :w1: is not gote, but sente.

What, then, is the value of the original position in Diagram 2, as a sente? It cannot be less (for Black) than that of the position after the sente sequence, because then White would lose points by the sente exchange. OTOH, it cannot be more, because then Black would not reply. So the value of the original position is 8 points, and the sente play, :w1:, gains 4 points. Then the reply, :b2:, also gains 4 points, for a net gain of 0. The reverse sente play moves to a position worth 9 points, and gains only 1 point. (Even though it is the reverse sente that gains points, we call this a 1 point sente.) This asymmetry of the values of the sente and reverse sente is characteristic of local sente.

Now, just because a play is local sente does not mean that it is global sente. However, it is likely to be played as sente. Any time that the largest play elsewhere gains less than 4 points and more than 1 point it is likely that White can play :w1: with sente and unlikely that Black can afford to play the reverse sente. That is what we mean when we say that White has the privilege of playing the sente.

The fact that the value after the sente sequence is the same as the value before it is reflected in the go proverb that sente gains nothing. (OC, it gains in the sense that it eliminates the reverse sente, but it gains no points.) Note that this proverb does not apply to global sente. It is quite possible to make a local gote or reverse sente play that leaves a reply that is the best play on the whole board. That kind of sente does gain points.

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Last edited by Bill Spight on Sat Dec 06, 2014 9:37 am, edited 2 times in total.
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 Post subject: Re: How to tell if a play or position is sente
Post #3 Posted: Fri Dec 05, 2014 10:30 pm 
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Do local double sente exist?

Now, what about local double sente? The same considerations apply as with regular sente. The value of the resulting position after both sente sequences is the same as the value of the original position. Sente gains nothing either way. Such positions exist, but we do not normally call them double sente, we call them miai. They are normally not played before the end of the game, except in ko situations. The only kind of double sente that makes gains is global double sente.

Unfortunately, yose textbooks, with few exceptions, talk about double sente as though it were local, labeling local positions as double sente without regard for the rest of the board. That is simply an error. It leads to confusion and unclear thinking about yose. That is not to say that pros make mistakes in actual games because of that. Maybe some of them do, but mostly they do not. If they do notice the inconsistency between what they teach and how they play, they do not know why and come up with some other explanation, so that they do not correct what they teach.

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 Post subject: Re: How to tell if a play or position is sente
Post #4 Posted: Sat Dec 06, 2014 12:17 am 
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First, good topic. This has been a topic of confusion for me for quite some time.

Bill Spight wrote:
The average value is 6.5, and the value of a play, assuming that it is gote, is 2.5 points.


I follow very clearly until the part about 2.5 points. Why is the gote play 2.5 points?

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 Post subject: Re: How to tell if a play or position is sente
Post #5 Posted: Sat Dec 06, 2014 12:29 am 
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Kirby wrote:
First, good topic. This has been a topic of confusion for me for quite some time.

Bill Spight wrote:
The average value is 6.5, and the value of a play, assuming that it is gote, is 2.5 points.


I follow very clearly until the part about 2.5 points. Why is the gote play 2.5 points?


Thanks, Kirby. I have edited the note accordingly. :)

Assuming that the position is gote, its value is 6.5. Then for Black to move to a position with a value of 9 gains 2.5 points, and a move by White to a position worth 4 gains 2.5 points. :)

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 Post subject: Re: How to tell if a play or position is sente
Post #6 Posted: Sat Dec 06, 2014 1:06 am 
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Bill,

your clearly local gote example might, under exceptional circumstances, be sente or reverse sente if the outer strings are not unconditionally independently alive and, e.g., the answering player might need to play a local negative ko threat.

Your value calculations presume using (the obvious) locales.

Quote:
What, then, is the value of the original position in Diagram 2, as a sente? It cannot be less (for Black) than that of the position after the sente sequence, because then White would lose points by the sente exchange. OTOH, it cannot be more, because then Black would not reply. So the value of the original position is 8 points, and the sente play, :w1:, gains 4 points. Then the reply, :b2:, also gains 4 points, for a net gain of 0. The reverse sente play moves to a position worth 9 points, and gains only 1 point. (Even though it is the reverse sente that gains points, we call this a 1 point sente.) This asymmetry of the values of the sente and reverse sente is characteristic of local sente.


Can you please explain the calculation of each of these values in greater detail?

Quote:
It is quite possible to make a local gote or reverse sente play that leaves a reply that is the best play on the whole board. That kind of sente does gain points.


In which sense does it gain points?

Quote:
what about local double sente? The same considerations apply as with regular sente. The value of the resulting position after both sente sequences is the same as the value of the original position


Please explain why the value (which value?) is still the same. Clearly, you do not mean the position's territory count because, if Black gets e.g. a hane-connect, White's territory has been decreased by 2 points while, if White gets a hane-connect, Black's territory has been decreased by 2 points. There is a difference of 4 points between the two resulting positions, which have the territoy count values X-2 and X+2. However, the original position's territory count must be in between at X.

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 Post subject: Re: How to tell if a play or position is sente
Post #7 Posted: Sat Dec 06, 2014 3:12 am 
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Bill

Before you go too far, some points you may wish to take on board from the non-mathematical part of your audience.

1. You appear to be using non-Japanese terms. The Japanese categories that you call "gote, sente and double sente" are to them "double gote, kata sente and double sente". I find the Japanese terms superior as double gote allows them to further talk about "gote sente" and "sente gote" and kata sente gets over one aspect of sente being used ambiguously in English.

2. I have never seen a proverb I Japanese that tells us to play double sente quickly, much less immediately. The only one I know advises us simply not to give them up to the opponent. Given that this advice is accompanied by comments (as in Kano) to manoeuvre (i.e. rather the opposite of quickly!) so as to get to a double sente ahead of the opponent), I think that covers aspects your version does not cover.

(The above is part of the reason I think that criticism of the Japanese texts can be unfair at times - they are being criticised either for things they didn't say or conceived differently. It is legitimate to address the whole problem from a western perspective, of course, but if that is the case it should be made plain and kept separate.)

3. There seems to be an unexpressed assumption that we are starting with some sort of base count for the whole board (White has an estimated X points and Black Y points), otherwise comments like "White gains 0 points" don't make sense. It seems to me perfectly feasible to have a system in which White has a gain expressed in terms of what he deprives Black of. Since, in addition, we have (or will have soon) the concepts of deiri counting and miai counting, plus "value of a position", this base method needs to have a name and an identity. It also needs to be defined. Some people appear to estimate territory by including assumptions about rights to make a certain play, others don't. You therefore need to identify which method lies behind your system.

4. "Value of position" needs definition, or at least discrimination.

5. I do not understand your sentence "Now let’s figure out the value of the position in Diagram 2, as though it were gote." Obviously I understand all the words, and even I can guess that 6.5 is based on 9 + 4, but I am at a loss to follow the procedure - why certain things are done and in a certain order. I gather RJ may have a similar problem, though maybe a bit beyond that (clearly I can't make progress to his level as I haven't crossed the first barrier yet).

6. I dispute that there is a proverb "sente gains nothing". That is just a western joke.

7. With various usages of sente washing around, should we not try to get away from the term "reverse sente"? I am sure the Japanese avoid it for good reason.

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 Post subject: Re: How to tell if a play or position is sente
Post #8 Posted: Sat Dec 06, 2014 4:48 am 
Oza

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Click Here To Show Diagram Code
[go]$$
$$ -------------------
$$ . . . . . . . . . . . . . . .
$$ . . . . . . . b . . . . . . .
$$ . . . . . . O . X . . . . . .
$$ . . . . . . O . X . . . . . .
$$ . . . . . . O . X . . . . . .
$$ O O O O O O O . X X X X X X X[/go]


An overly simplistic example, but wouldn't you consider b to be double sente in almost all situations? It is hard to perceive of any whole board situation where there could be anything bigger then letting the opponent jump in.

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 Post subject: Re: How to tell if a play or position is sente
Post #9 Posted: Sat Dec 06, 2014 5:01 am 
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An active fight elsewhere can be more urgent easily.

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 Post subject: Re: How to tell if a play or position is sente
Post #10 Posted: Sat Dec 06, 2014 5:56 am 
Oza

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Quote:
An active fight elsewhere can be more urgent easily.


Surely the assumption that the players are looking at boundary plays in a quiescent position is built in.

But the whole question of assumptions seems to bedevil this topic.

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 Post subject: Re: How to tell if a play or position is sente
Post #11 Posted: Sat Dec 06, 2014 6:13 am 
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There are good purposes for local-only studies and other good purposes for global contexts and proper declaration of assumptions:)

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 Post subject: Re: How to tell if a play or position is sente
Post #12 Posted: Sat Dec 06, 2014 7:00 am 
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Well, this is not that difficult to identify sente and gote...

sente :
Attachment:
images.jpg
images.jpg [ 7.95 KiB | Viewed 4919 times ]


gote :
Attachment:
photo.JPG
photo.JPG [ 111.24 KiB | Viewed 4919 times ]

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 Post subject: Re: How to tell if a play or position is sente
Post #13 Posted: Sat Dec 06, 2014 8:21 am 
Honinbo

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DrStraw wrote:
Click Here To Show Diagram Code
[go]$$
$$ -------------------
$$ . . . . . . . . . . . . . . .
$$ . . . . . . . b . . . . . . .
$$ . . . . . . O . X . . . . . .
$$ . . . . . . O . X . . . . . .
$$ . . . . . . O . X . . . . . .
$$ O O O O O O O . X X X X X X X[/go]


An overly simplistic example, but wouldn't you consider b to be double sente in almost all situations? It is hard to perceive of any whole board situation where there could be anything bigger then letting the opponent jump in.


How about this?

----

Click Here To Show Diagram Code
[go]$$
$$ -------------------
$$ . . . . . . . . . . . . . . .
$$ . . . . . . . a . . . . . . .
$$ . . . . . . O . X . . . . . .
$$ . . . . . . O . X . . . . . .
$$ . . . . . . O . X . . . . . .
$$ O O O O O O O . X X X X X X X[/go]


A play at "a" is a huge gote. (N. B. We know that it is gote because it gains points in a symmetrical position.)

Click Here To Show Diagram Code
[go]$$
$$ -------------------
$$ . . . . . . . . . . . . . . .
$$ . . . . . . 2 1 . . . . . . .
$$ . . . . . . O . X . . . . . .
$$ . . . . . . O . X . . . . . .
$$ . . . . . . O . X . . . . . .
$$ O O O O O O O . X X X X X X X[/go]


:w2: is also huge, even though it is not as huge as :b1:. (N. B. If we go to a little trouble, we can figure out that it gains 3 points less than :b1:.) In fact, there is unlikely to be a larger play on the board. That means that Black can probably play :b1: with sente (and vice versa if it is White's turn to play).

It also means that :b1: (or :w1:) is likely to be the largest play on the board, and should be played now.

----

Any problem with that? :)

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 Post subject: Re: How to tell if a play or position is sente
Post #14 Posted: Sat Dec 06, 2014 8:49 am 
Oza

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Bill Spight wrote:
Any problem with that? :)


Well, by that line of argument the concept of sente is no existent. How come there has been a word for it for so long?

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 Post subject: Re: How to tell if a play or position is sente
Post #15 Posted: Sat Dec 06, 2014 8:54 am 
Dies with sente
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DrStraw wrote:
Click Here To Show Diagram Code
[go]$$
$$ -------------------
$$ . . . . . . . . . . . . . . .
$$ . . . . . . . b . . . . . . .
$$ . . . . . . O . X . . . . . .
$$ . . . . . . O . X . . . . . .
$$ . . . . . . O . X . . . . . .
$$ O O O O O O O . X X X X X X X[/go]


An overly simplistic example, but wouldn't you consider b to be double sente in almost all situations? It is hard to perceive of any whole board situation where there could be anything bigger then letting the opponent jump in.


How about this situation? (0 komi and that corners are not invadable for simplicity)

Click Here To Show Diagram Code
[go]$$B Not double sente
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . a . . . . . . . . . |
$$ | . . O . . . . . O . X . . . . . X . . |
$$ | . . . , . . . . O , X . . . . , . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | O O O O O O O O O , X X X X X X X X X |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . , . . . . O , X . . . . , . . . |
$$ | . . O . . . . . O . X . . . . . X . . |
$$ | . . . . . . . . . b . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


I think in this case neither a nor b will be responded to locally. Instead they will be played as miai, like Bill mentioned. If white plays a local response, she will lose for sure, by about 7 points:

Click Here To Show Diagram Code
[go]$$B a, b, c, d, e follow :w10:
$$ ---------------------------------------
$$ | . . . . . . . 6 5 7 . . . . . . . . . |
$$ | . . . . . . 8 . 2 1 e . . . . . . . . |
$$ | . . O . . . . . O d X . . . . . X . . |
$$ | . . . , . . . . O , X . . . . , . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | O O O O O O O O O , X X X X X X X X X |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . , . . . . O , X . . . . , . . . |
$$ | . . O . . . . . O c X . . . . . X . . |
$$ | . . . . . . b . 4 3 . . . . . . . . . |
$$ | . . . . . . . 0 9 a . . . . . . . . . |
$$ ---------------------------------------[/go]


However, if White responds with miai, there is perhaps a chance?

Click Here To Show Diagram Code
[go]$$B White has a fighting chance.
$$ ---------------------------------------
$$ | . . . . . . 3 . . . . . . . . . . . . |
$$ | . . . . . . . . . 1 . . . . . . . . . |
$$ | . . O . . . . . O . X . . . . . X . . |
$$ | . . . , . . . . O , X . . . . , . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | O O O O O O O O O , X X X X X X X X X |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . . . . . . O . X . . . . . . . . |
$$ | . . . , . . . . O , X . . . . , . . . |
$$ | . . O . . . . . O . X . . . . . X . . |
$$ | . . . . . . . . . 2 . . . . . . . . . |
$$ | . . . . . . . . . . . . 4 . . . . . . |
$$ ---------------------------------------[/go]

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 Post subject: Re: How to tell if a play or position is sente
Post #16 Posted: Sat Dec 06, 2014 9:13 am 
Dies with sente
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John Fairbairn wrote:
5. I do not understand your sentence "Now let’s figure out the value of the position in Diagram 2, as though it were gote." Obviously I understand all the words, and even I can guess that 6.5 is based on 9 + 4, but I am at a loss to follow the procedure - why certain things are done and in a certain order. I gather RJ may have a similar problem, though maybe a bit beyond that (clearly I can't make progress to his level as I haven't crossed the first barrier yet).


I can't speak for Bill, but this looks like the way I was taught about valuing gote endgame. My mathematical interpretation of this model is as a recursive function:

Value of (Position) = ( Value of (Position + best local Black play) + Value of (Position + best local White play) ) / 2

That is, we assume that it is equally likely that either player will play the next move. This can be a bit complex because you have to consider every sequence of moves in a large binary tree to get the valuation (Black-White-Black, Black-White-White, Black-Black-White, Black-Black-Black + ... etc.) and could the sequence of plays could be infinite (say if there's some sort of ko for example). But for this case it resolves very quickly after a few moves, just White, Black-White, Black-Black (assuming that both groups are unconditionally alive outside of this region.) So:

Value of (Position) = ( Value of (Position + Black) + Value of (Position + White) ) / 2
Value of (Position + Black) = ( Value of (Position + Black-Black) + Value of (Position + Black-White) ) / 2
Value of (Position + Black-Black) = 0
Value of (Position + Black-White) = 8
Value of (Position + Black) = ( 0 + 8 ) / 2 = 4
Value of (Position + White) = 9
Value of (Position) = ( 4 + 9 ) / 2 = 6.5

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 Post subject: Re: How to tell if a play or position is sente
Post #17 Posted: Sat Dec 06, 2014 9:26 am 
Honinbo

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DrStraw wrote:
Bill Spight wrote:
Any problem with that? :)


Well, by that line of argument the concept of sente is no existent. How come there has been a word for it for so long?


It's a gote. You want sente, show a sente. ;)

Look, I did use the term, sente, in the phrase, with sente. That is appropriate usage in this situation. :)

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 Post subject: Re: How to tell if a play or position is sente
Post #18 Posted: Sat Dec 06, 2014 10:02 am 
Honinbo

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RobertJasiek wrote:
Bill,

your clearly local gote example might, under exceptional circumstances, be sente or reverse sente if the outer strings are not unconditionally independently alive and, e.g., the answering player might need to play a local negative ko threat.


I was following the standard convention that the framing stones are immortal. I have added an edit to that effect. :)

Quote:

Your value calculations presume using (the obvious) locales.

Quote:
What, then, is the value of the original position in Diagram 2, as a sente? It cannot be less (for Black) than that of the position after the sente sequence, because then White would lose points by the sente exchange. OTOH, it cannot be more, because then Black would not reply. So the value of the original position is 8 points, and the sente play, :w1:, gains 4 points. Then the reply, :b2:, also gains 4 points, for a net gain of 0. The reverse sente play moves to a position worth 9 points, and gains only 1 point. (Even though it is the reverse sente that gains points, we call this a 1 point sente.) This asymmetry of the values of the sente and reverse sente is characteristic of local sente.


Can you please explain the calculation of each of these values in greater detail?


I think that the best defense of this way of figuring the value of sente is the method of multiples. See http://senseis.xmp.net/?MethodOfMultiples . :)

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Quote:
It is quite possible to make a local gote or reverse sente play that leaves a reply that is the best play on the whole board. That kind of sente does gain points.


In which sense does it gain points?


Gote and reverse sente plays and sequences gain points (unless you want to include infinitesimals, such as dame.)

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Quote:
what about local double sente? The same considerations apply as with regular sente. The value of the resulting position after both sente sequences is the same as the value of the original position


Please explain why the value (which value?) is still the same.


In positions without kos the value of the position lies between the values of the correct plays or alternating sequences of plays when Black plays first and when White plays first. As we have seen, if a position is sente the value of the position is unchanged after the sente sequence. Assuming that a position is double sente does not alter that fact. If a supposed sente sequence gains points, then the reply is worth less than the initial play, which means that the initial play is not (local) sente.

Quote:
Clearly, you do not mean the position's territory count because, if Black gets e.g. a hane-connect, White's territory has been decreased by 2 points while, if White gets a hane-connect, Black's territory has been decreased by 2 points. There is a difference of 4 points between the two resulting positions, which have the territoy count values X-2 and X+2. However, the original position's territory count must be in between at X.


The double hane-connect that you describe is not a local double sente. It is double sente only if both replies are better than playing elsewhere. (Edit: Which means that the sense of double sente is global.) The Kano examples are double hane-connects, but one is a 7 point sente and one is a 20 point gote. :) Neither are local double sente. The 20 point gote is very likely to be global sente, but the 7 point sente is not.

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Last edited by Bill Spight on Sat Dec 06, 2014 2:20 pm, edited 2 times in total.
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 Post subject: Re: How to tell if a play or position is sente
Post #19 Posted: Sat Dec 06, 2014 11:29 am 
Oza

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The Kano examples are double hane-connects, but one is a 7 point sente and one is a 20 point gote. :) Neither are local double sente. The 20 point gote is very likely to be global sente, but the 7 point sente is not.


Sorry to harp on these points to do with Kano, but is it not the case that in practical terms he is correct? According to Ishida's book on counting, moves in the fuseki are typically worth something like 25 points. I assume middle-game moves are typically worth that and more - at any rate too much to make it feasible to play the 20-point sente referred to. But at certain points during the middle game the game goes quiescent (the temperature drops?) and when it does, the value of plays drops dramatically and the large boundary plays come to the fore (i.e. yose but not yet the endgame). At that point it seems easy to imagine the 7-point side getting the right to play first. Statistically I presume we can say that it's a 50-50 chance that the player who emerges from the middle-game turbulence with the move will be the one with the 7-point gote. The only factor then is at what level the large boundary plays (at least those unconnected with unfinished middle game fights) start. If it's 8 or 9 points, the 7-point sente guy perhaps loses out (and we can assume the 20-point guy never will), but will that really be often enough to dismiss Kano's example.

For those unfamiliar with Kano's book, he himself points out the different values for each side in this position, and - as I have said before - plainly states that it is an important task of the players to manoeuvre in the fighting beforehand to get the right to play the sente move. The 7-point guy may have to be manoeuvre harder, or compromise more, but he is aware of the goal and can decide accordingly.

By sheer chance, I was browsing through some chess books today and I came across a similar concept there. The rather nice phrase used by John Watson in "Secrets of Modern Chess Strategy" was "The Initiative Dance". This is the heading of a whole chapter, mostly text, and it all seems highly relevant to go and sente - may even be the same thing. To pick out a few phrases to illustrate, he also uses "the mysteries of momentum", "dynamic potential", "mysticism", "Continental Metaphysics", "strategy of long-term provocation", "dynamic give-and-take", "dynamism and provocation", "paradoxical comings and goings of momentum and initiative". His final sentence is "And the correct use of provocation is a skill which separates the finest players from the rest of us."

He also says that this is an area likely to become increasingly important among top chess players (and Mihail Suba seems to be the guru). I have mentioned before the notion that mysterious and very early probes are becoming an increasing feature of modern fuseki. It seems plausible to wonder whether this parallels the chess innovation - rather than probes we should be calling this provocation and rather than simply trying to see how the opponent will react the agent provocateur us really trying to control the "initiative dance" by adding dynamic potential and momentum to the position.

Several other chapters in the Watson book seem to cover areas in which modern go is changing along the same lines as chess.

I infer from all that that this initiative/sente business is nothing like as simple as some people claim, and I'm relieved to see that Watson adds "to an ultra-logical critic, this may just sound like the ravings of a weak player" and then chops the ULC off at the knees.

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 Post subject: Re: How to tell if a play or position is sente
Post #20 Posted: Sat Dec 06, 2014 11:58 am 
Honinbo

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John Fairbairn wrote:
Bill

Before you go too far, some points you may wish to take on board from the non-mathematical part of your audience.

1. You appear to be using non-Japanese terms. The Japanese categories that you call "gote, sente and double sente" are to them "double gote, kata sente and double sente". I find the Japanese terms superior as double gote allows them to further talk about "gote sente" and "sente gote" and kata sente gets over one aspect of sente being used ambiguously in English.


If I had been writing for a Japanese audience I would have used those terms. :)

Quote:
2. I have never seen a proverb I Japanese that tells us to play double sente quickly, much less immediately. The only one I know advises us simply not to give them up to the opponent. Given that this advice is accompanied by comments (as in Kano) to manoeuvre (i.e. rather the opposite of quickly!) so as to get to a double sente ahead of the opponent), I think that covers aspects your version does not cover.


The English version that I recall is to play double sente early. I thought that it came from Go Proverbs Illustrated, but I guess not, since you surely have a copy handy. I picked it up way back when, so I do not recall where.

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(The above is part of the reason I think that criticism of the Japanese texts can be unfair at times - they are being criticised either for things they didn't say or conceived differently. It is legitimate to address the whole problem from a western perspective, of course, but if that is the case it should be made plain and kept separate.)


Well, for one thing I am not criticizing the proverb, either version of it. :) For another, I do not regard my critique as Western. Sure, I am a Westerner, but I did study Oriental philosophy starting at age 11, and pre-modern Western thought in my 20s. I am hardly an avatar for modern Western thinking. ;)

Quote:
3. There seems to be an unexpressed assumption that we are starting with some sort of base count for the whole board (White has an estimated X points and Black Y points), otherwise comments like "White gains 0 points" don't make sense.


Think Absolute Counting (TM). :)

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4. "Value of position" needs definition, or at least discrimination.


Again, see O Meien. :)

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5. I do not understand your sentence "Now let’s figure out the value of the position in Diagram 2, as though it were gote." Obviously I understand all the words, and even I can guess that 6.5 is based on 9 + 4, but I am at a loss to follow the procedure - why certain things are done and in a certain order. I gather RJ may have a similar problem, though maybe a bit beyond that (clearly I can't make progress to his level as I haven't crossed the first barrier yet).


OK, let's look at a similar (local) gote.

Click Here To Show Diagram Code
[go]$$W Diagram 3 Gote
$$ -------------------
$$ . . O . . O O . O . X . .
$$ . . O O O X X X X X X . .
$$ . . . . . . . . . . . . .[/go]


Sorry, I have to run now. More later. :)

Meanwhile, you might like to figure out the values of the positions and plays inherent in this position. :)

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— Winona Adkins

My two main guides in life:
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Everything with love. Stay safe.

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