According to Bill Spight or Robert Jasiek approaches double sente positions seem to not exist. In the context of their method it must be true but as a Go player I have not the same feeling.
Let's take the following example:

Click Here To Show Diagram Code

[go]$$B
$$ --------------------------------
$$ . X O . O . . b a . . X . X O .
$$ . X O O O . O O X X . X X X O .
$$ . X X X O O X O X O X X O O O .
$$ . . . X X X X X O O O O O . . .
$$ . . . . . . . . . . . . . . . .[/go]

Assuming an ambiant temperature greater than t = 1 my analysis is the following: to avoid the opponent to play hane, both players must play sagari in sente BEFORE decreasing the ambiant temperature under t = 1. The position being symetrical this position is for me sente for both players; one of the player (it does not matter which one!) will necessarily play sagari in sente to avoid playing in the environment and decreasing the temperature under t = 1.

Local double sente vs. global double sente.

How do you call this position as a local position?

For this class of positions with tentative sente and gote options for both players, I have not developed a local nomenclature.

OK Robert.
I said I considered this position double sente. That means that my analyse tells the go players that any of the two players can choose the sente option and tells also that one of the two players (it does not matter which one) must eventually play this sente move.
Robert, what your method tells the go players?

As I have explained before, my theory is not developed for a local endgame with both players' tentative gote and sente options but some option can be temporarily ignored for indicative study of tentative move values. I have also suggested many times to consider global double sente for informal theory fot go players, and this is more suitable for your example.

I don't think there's a standard term yet. Personally I call it: "This will become double sente when the game temperature drops below <number>". Who gets to play it as sente depends on who plays the move elsewhere which causes the temperature to drop below the threshold.

Gerard: It sounds like you are seeking something that is useful in practical terms while at the same time seeking to find the far end of a fart. The two things are incompatible.

Assuming practicality is your main concern, I would suggest two points to consider.

1. Follow O Meien's advice as in his following table:

* Advantage of first move = half the value of a move
* Margin of error = half the advantage of first move

* If it is the opponent’s turn to play, even if you add the advantage of first move and the margin of error to the opponent’s territory, if you are ahead you have “certainty.”

* If there is an outstanding big move for the opponent, assume he can play there then count. Add the advantage of first move to your territory and add the margin of error to the opponent’s territory.

He gives several worked examples and one of them (at least) includes a double-sente issue in the above context just like the one you give.

2. Sente has too many meanings in English. I think you may find a clearer path if you think of the initiative for the global context and sente only for local boundary plays.

O Meien does not talk directly about the initiative, but his book, after all, is about absolute counting. However, who has the initiative can be assessed in additional ways to strict counting (e.g. number of mistakes made so far, weak points/groups etc - and for this QARTS is useful), so in practice you don't really need to worry about fancy terms such as temperature.

I suppose what it comes down to is that you have to decide what you main focus is: mathematics or playing actual go. It's too much of a handful to have both.

OK Robert, OC, if you have not developed a nomenclature for class of positions with tentative sente and gote options for both players then you can hardly find a double sente position.
Double sente positions can only appear if you try to put a name on all positions including candidates for a double sente status.
BTW you also did not define what a seki is or what a double ko is, did you?

This is not specific to O Meien but common in modern endgame theory.



Temperature is not a fancy term but a shortcut for "value of the largest move elsewhere" and as a word a good metaphor for its meaning. We use go terms to express things more efficiently. It is more efficient to say "temperature" than to say "value of the largest move elsewhere" all the time.

Maybe your disliking of the term comes from your disliking of its mathematical origin. "God forbid, in some respects, mathematics to be more useful than professional", might be your thinking, but this is your personal preference, not something everybody must share.



During the late endgame, in which Gerards example is, a margin of error does not introduce anything useful. Quite contrarily, it introduces superfluous information.

During the middle game or early endgame, a margin of error might be useful. I have considered whether I would want to use some as a go player but come to this conclusion: a particular number for a margin of error as a modifier of the temperature does not give me any meaningful information that I would not already have by the awareness that there is some margin of error of unknown size.



While I understand the purpose, the time for calculating the value for this purpose is better invested in more careful direct endgame evaluation and decisions.

("Certainty" might also be called a fancy name. You promote it because it comes from a professional. If other certainties in endgame theory come from mathematics, you would reject it, wouldn't you? Become more objective in what you like and dislike!)



Ok, but every meaning has a good purpose. One just must avoid careless use of the word without clarification, as in "local sente" etc., like one must for other ambiguous terms related to life and death, thickness or whatever. You have studied some other terms in greater detail - we endgame students consider endgame terms in greater detail.



Application of such a rough theory would make me weaker. It is something to forget rather than advertise.



Mathematics is our (except you, we know) friend, like professional advice, AI judgements, strong amateur advice and expert advice are our friends for playing actual go if we are serious about becoming stronger. At the same time, we must be aware of the limitations of each source of input. Limitations, however, do not mean uselessness.

(And if you were serious about rejecting maths out of disliking, you should not advertise O Meien's maths or learning values per shapes by heart, either. Instead, you would claim that nothing but intuitive endgame choice would be enough to reach 9p level.)

It appears it is just a matter of wording, Xela.

Click Here To Show Diagram Code

[go]$$B
$$ --------------------------------
$$ . X O . O . . . . O . X .
$$ . X O O O . O O X X X X .
$$ . X X X O O X X X . . . .
$$ . . . X X X X . . . . . .
$$ . . . . . . . . . . . . .[/go]

In that case, to be consistant, instead of saying that the position above is "sente for black" why not saying "this will become sente for black when the game temperature drops below <number1>". In addition, when the game temperature drops below <number2> then this position will become sente for black and reverse sente for white, and finally when the game temperature drops below <number3> then this position will become gote for both players.

I do not see what harm when you keep simple wording as "sente for black" or "double sente"? It is a little mysterious for me.

Except for countless obviously dominated options, a local endgame with one player's gote and sente options is already an infrequent exception in practice. A local endgame with both players' gote and sente options (other than doubly ambiguous) is even much less frequent in practice.

From a theoretical POV, you have every right to criticise Bill Spight and me not to have solved go entirely yet. From a practical POV, we can handle the very few local endgames with both players' gote and sente options without having a complete specialised theory for it (yet).



Recall that you entered discussion decades later than me! In 2004 on https://home.snafu.de/jasiek/j2003.html I defined in-seki, from which I derived a definition of seki (I do not have an URL at hand, but it is obvious anyway). For double ko, you find something of 2008 here: https://home.snafu.de/jasiek/ko_types.pdf Later, I made a private attempts for a finer classification of ko types with large ko strings than in 2010 in https://home.snafu.de/jasiek/ko.pdf but concluded that it would amount to about one definition per specific shape.

Needless to say, from 1996 on, there were my predecessors for specialised rulesets, such as
https://home.snafu.de/jasiek/newko.html
https://home.snafu.de/jasiek/ingkolec.txt
https://home.snafu.de/jasiek/ingko_epilogue.pdf

Harm occurs when greater precision is needed or you disrespect others' greater precision by describing it as if they lacked it.

Do you mean precision for the defintion itself or precision for the various evalutions (counts or move values)?

The harm occurs when people play their "double sente" moves too early.

"Sente for black" is not so harmful. It's one-sided, it's not going to go away (usually!), so you can wait until later.

But "double sente": I need to play that right away, or else the other person will get it! (Not true, but a too-common misunderstanding.)

For example, here's a position from the Lee Sedol-Gu Li jubango, game 5.

Click Here To Show Diagram Code

[go]$$Wc19 Position after move 37: 'a' is not sente
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . a b . . . . . . . . . . . |
$$ | . . O . . O . X . . . . . X . . . . . |
$$ | . X . O . . . . . B . . . . . X X . . |
$$ | . . . . . . . . . . . . . . . . . O . |
$$ | . . X O O . . . . . . . X . O . O . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . X . . . . . . . . . X O O O . |
$$ | . . . . . . . . . . . . . . . X X O . |
$$ | . . O . . . . . . . . . . . . . . X . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . O . . . . . O . . O . . . . . . |
$$ | . . . . . O . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

After black plays the marked stone, the top centre is now looking like black's territory, so a is "double sente". Back when I was a 5 kyu, I would have played white a immediately. And a lot of my kyu opponents would have obligingly answered at b. In fact, white ended up playing a much later, on move 112.

Click Here To Show Diagram Code

[go]$$Wc19 *Now* it's double sente!
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . a . . . . . . . . . X . . |
$$ | . . O . . O . X . . . . . X . . . O . |
$$ | . X . O . . . . . X X . . . . X X X O |
$$ | . . O . . . . . . . O . . . . . . O . |
$$ | . . X O O . . . . . . . X . O . O . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . X . . . . . . . . . X O O O . |
$$ | . . . . . X . . . . . . . . . X X O . |
$$ | . X O . . X O . O . O O . . . . . X . |
$$ | . . . . . X O . . O X O O . . . X . . |
$$ | . X X O O X O . X O X X O X . . . . . |
$$ | . O X X O X O X O . X X X X . X . . . |
$$ | O . O O X X O X . O X O O X O X . . . |
$$ | . O O X O O X X O . O X O . . X . . . |
$$ | . . . X . O O O . . O X X . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Oops your example is quite different: in my position it does not matter which player will play her sente move, the result will be the same. In your example I see a huge difference when I compare the result after a white move and the result after a black move. I will never consider such position as double sente.

Why do you say in the last diagram is double sente position? I guess it is because you think that the ambiant temperature is small comparing to the threats involved by the sente moves. But assume temperature is high so that both players will firstly play several moves in the environment. At the moment temperature drops to a certain temperature t1 one player will decide to play locally. Are you sure it will be a sente move? And are you sure the opponent will be also able to play a sente move at this temperature t1?

Look at this provocative exmple

Click Here To Show Diagram Code

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

Assume ambiant temperature t < 1.

Click Here To Show Diagram Code

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

The sequence to is sente for black isn't it?
OC this position with ambiant temperature t < 1 is also sente for white?
Do you want really say it is a double sente position? I guess not. You will certainly say it is a "global" double sente position (meaning that take into account the temperature of the environment) but not a local double sente position.

Conceptual precision. When we have said something for a specific kind of, in this case, double sente, namely for local double sente (its non-existence!), then it is impolite to speak about double sente more generally, showing some example and leaving the reader in doubt whether the example would be a counter-example to our theorem when, in reality, you mean some other concept: global double sente. (At other times, you have been more careful and polite about the matter.)

"Double sente" is a concept which exists in the go language for a very long time. For sure that does not mean that the defintion of this term is very clear OC, but what is impolite is to define this wording in a different context, to decide your defintion is the only acceptable one, and in addition to conclude that this concept simply does not exist!
Those interested by your defintion will buy your book but as far as I am concerned I will continue to use this "double sente" as many other go players do .i.e. in an informal context, trying simply to have a common understanding. OC,I can try to differentiate "global double sente" to "local double sente". For me that's a quite interesting idea but because you claim that "local double sente" does not exist (though I understand it could not exist because the candidate positions for being local double sente are just unnamed!) such discussion cannot take place OC.

And as such often is a local gote, misleading everybody by the name "double sente" and by pretending bad values to be move values with the fake information on when to play in them. The centuries(?) of wrong teaching must be overcome. You are one of the few doing better by also studying good moments of local play.



No. It is not a different context, but is the most frequent traditional context (appearing in old textbooks) with now added clarity. The less frequent traditional context of what later Bill Spight discussed and then I called global double sente (or double sente in the global positional context) was infrequently associated by amateur dans as "try to play there before the opponent but not too early" because of an awareness that the opponent would tenuki rather than accept a double sente fate.



For its purpose, my definition is one of four possible equivalent definitions. Therefore, it is not the only possible definition but any of the three alternative definitions would work equally well. This fact of equivalence of four alternatives is a strong indication of how very useful the definition is. The many theorems derived from the definition of other standard types of local endgames are another strong sign of how very useful the definition is.

A global (instead of local) study scope permits another (or other) definition(s) of (then global) double sente. Therefore, the definition of local double sente does not describe concepts of double sente completely. (Besides, there is the related doubly ambiguous type.)

Other local definitions might be suggested but will they have similar success of equivalence and applications in theorems? A global definition might be suggested but which is the best remains to be seen by its scope of application.

Since you question the usefulness of the concept of local double sente due its infamous non-existence, do not forget to notice, as already John pointed out, that O Meien forwent double sente entirely when evaluating local endgames! He must also have been aware that non-existence would be a strong possibility.



There won't be such a common understanding because most go players only familiar with some related informal context do not have a clear understanding. Many of them are kyus still repeating the same mistakes of the past: playing too early because something is called double sente or playing too late because the traditional fake move value suggests such.



Nonsense. Of course, discussion is possible due to the context of all the other types that do exist and therefore give a good understanding of what a local double sente would be.

OK let's try to continue the discussion.
What about the following definition using thermography: a double sente position is a position for which a part of the mast is purple.
With this definition it does not remain a lot of positions does it?