Can a double sente position exist?

[Gérard TAILLE]

everything becomes far easier indeed.

With algebra for every go player?! You need to hide solving systems of equations when selling it as easy for every go player!

No Robert you are confusing the defintion of "sente position", which could be quite simple, with the "proof" that a given position is really a "sente position".
For a simple position it is easy to see if a given position is really a "sente position" according to the defintion, but for a difficult position it may be complicated to prove if this position is sente or not. In any case however, the defintion itself can be simple.

Similarly if you take a given game G, you can define the score of G as being the best score the players can reach. Because the god plays may not be obvious you see that though the defintion is quite simple and understanbable by any go player, finding this score can be quite difficult indeed.

If in your method the defintion is also the proof then I understand clearly why this defintion can be quite complicated!

[RobertJasiek]

you are confusing [...]
If in your method the defintion is also the proof

LOL, no.

[Gérard TAILLE]

you are confusing [...]
If in your method the defintion is also the proof

LOL, no.

Good news Rboert.

With algebra for every go player?! You need to hide solving systems of equations when selling it as easy for every go player!

Seeing that without knowing it, you pretended that my defintion cannot be simple, I had to conclude that yours is probably quite complicated for a go player. Fine if it not the case (!). I am sure the readers of yours books know perfectly that your defintions are quite simple and, respecting your works, I will not ask you to give us your own correct and formal defintion of a sente position.

[RobertJasiek]

The reason why my methods of classifying positions or move decisions are comparatively simple is: they are about calculating a value or comparing two values. Even if application must be interative because variations are, at every step, one compares values. Algebra beyond that occurs in the proofs but go players never need to understand the proofs to apply the theory.

[Gérard TAILLE]

The reason why my methods of classifying positions or move decisions are comparatively simple is: they are about calculating a value or comparing two values. Even if application must be interative because variations are, at every step, one compares values. Algebra beyond that occurs in the proofs but go players never need to understand the proofs to apply the theory.

Does that mean that the "sente position" DEFINITION needs calculating one or two values you have to compare?

[RobertJasiek]

Of course.

[Gérard TAILLE]

Of course.

That is the point Robert. If you need first a calculation to DEFINE if a position is sente or not, then providing the position is quite difficult, you simply cannot DEFINE what means the "position is sente" because the needed calculation may be too complex.

Take my other example where I define the score of a game G as being the best score the players can reach. Calculating the score may be difficult but the DEFINITION itself needs no calculation and as such appears simple and understandable by each go players.
It is the same for defining a "sente position". If you need a preliminary calculation to define what a sente position is, then this defintion appears to me complex and may even not be understandable by each go player.

[RobertJasiek]

If you need first a calculation to DEFINE if a position is sente or not

No.

The definition is general for a class of positions. For a particular position, the definition is APPLIED by determining the values.

[Gérard TAILLE]

If you need first a calculation to DEFINE if a position is sente or not

No.

The definition is general for a class of positions. For a particular position, the definition is APPLIED by determining the values.

Look to your naive definition:
"one player has a sente sequence and the opponent has a gote sequence".
Ignoring that a "sente sequence" and a "gote sequence" are not defined, this defintion is quite good. It is quite well understandable by any player and this defintion do not imply explicitly any more or less long calculation.

In another post you, taking into account only simple positions you defined the status of sente position as:
"local sente := MSENTE > MGOTE"
Here it is quite different. The MSENTE and MGOTE values being explicitly compared in the defintion itself then you cannot avoid calculating them to apply the defintion. It is not as understandable for a go player who have to learn what means MGOTE and MSENTE and must learn how to calculate them.
In addition you already explained that this defintion cannot be used for difficult positions (with various sente and gote options for both players). That means that this defintion is not general.

You see the difference? For me, to reach the best defintion, you have only to change the wording of you naive defintion, without introducing explicitly values you have to calculate.

[RobertJasiek]

to reach the best defintion, you have only to change the wording of you naive defintion, without introducing explicitly values you have to calculate.

What is your related suggestion of some, IYO, possibly better definition modifying my naive one?

[Gérard TAILLE]

to reach the best defintion, you have only to change the wording of you naive defintion, without introducing explicitly values you have to calculate.

What is your related suggestion of some, IYO, possibly better definition modifying my naive one?

OK with my method the defintion look like the following.

Definition of a sente position P:
Let’s the players play the game G made of the local position P, a rich environment at a high temperature, and black to play.
The ambient temperature will drop slowly until a temperature t at which black (resp. white) COULD play locally in P and reach however the best score.
If at this temperature t, white (resp. black) MUST play in the environment to reach the best score, then the position is said to be a black (resp. white) sente position.

Note that this defintion do not use values you have to calculate and compare, and do not use the undefined wording "sente sequence" or "gote sequence".

[RobertJasiek]

Is this a definition just for me or do you suggest it to be easily understood by all players?

(For my better understanding: "black to play" - why not "white to play"?)

[Gérard TAILLE]

Is this a definition just for me or do you suggest it to be easily understood by all players?

Basically it was an answer for you.
It is OC also for all go players knowing how to play a game in a rich environment.
For the other players I can OC replace the rich environment by an ideal environment like the set of gote area {0.01, 0.02, 0.03 ...., 99.98, 99.99, 100.00} but I would clearly prefer to use the rich environment.
In this context, before giving my definition of a "sente position", it is essential to firstly explain how to play a game with a rich environment. I guess you do not need such explanation (otherwise you can just open another topic on this forum and will help you).

(For my better understanding: "black to play" - why not "white to play"?)

It is only a pure convention by analogy with a real go game. It does not matter but a choice has to be made.
What is important here is to choose who is to play in G in order to show the go player that G is not a position but a game.

[Gérard TAILLE]

to reach the best defintion, you have only to change the wording of you naive defintion, without introducing explicitly values you have to calculate.

What is your related suggestion of some, IYO, possibly better definition modifying my naive one?

OK with my method the defintion look like the following.

Definition of a sente position P:
Let’s the players play the game G made of the local position P, a rich environment at a high temperature, and black to play.
The ambient temperature will drop slowly until a temperature t at which black (resp. white) COULD play locally in P and reach however the best score.
If at this temperature t, white (resp. black) MUST play in the environment to reach the best score, then the position is said to be a black (resp. white) sente position.

Note that this defintion do not use values you have to calculate and compare, and do not use the undefined wording "sente sequence" or "gote sequence".

As I said in another post the defintion above was only an answer to Robert question. In addition you can see that I use the wording "with my method the defintion LOOKS LIKE the following".
The reason for that is simple: my "real" definition uses explicitly the way I use a rich environment while in the proposal above I tried to avoid showing how works in detail a game in a rich environment.
As a consequence I am not quite happy with the defintion above while it looks an improvement comparing to the naive defintion proposed by Robert.
If someone is interested I can show you how I use a rich environment and what is my best defintion of a sente move.

BTW how do you analyse the following position:

$$B $$ ----------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . X X O O O . . . . . . | $$ | X X X X X X X X X . . . O O O O O O O | $$ | . . . , . . . . . , . . . . . , . . . |

Click Here To Show Diagram Code

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

Sente, gote?
This position seems a good test for your own defintion of a sente or gote position.