Sente gains nothing

Paths: <= Endgame =>   ·   <= Go Proverbs =>
  Difficulty: Intermediate   Keywords: EndGame, Proverb

This proverb seems counterintuitive. Sente certainly feels like it gains something! ;-) And, strictly speaking, it is not true. Sente does gain something: It keeps the opponent from playing the reverse sente. [1]

Using the simile in Winning Ways, playing sente is like cashing a check before it expires. You are claiming what is rightfully yours. Playing sente (and getting a response) normally leaves the count unchanged.[2]

When you are estimating the score, you assume that sente plays are made and answered, for precisely the reason that the count stays the same.

Example:

[Diagram]
Sente gains nothing  

After the sente sequence, W1 - B2, Black has 4 points of territory in the corner. We still count the corner as 4 points for Black before the sente. We consider White as owning the sente (White has the privilege of playing the sente), because of its large threat. Under normal circumstances White will be able to play at W1 with sente before Black can afford to play the reverse sente.

After a sente sequence each player has made the same number of plays. If the first player has gained anything, it is for free. This proverb is the go version of the saying, There is no such thing as a free lunch.

(Note: This proverb does not apply to playing a gote with sente. That does make a profit, and for free!)

I find this last line confusing. Does it mean having sente and using it to play a gote move? Or is it some sort of alchemy that takes a gote move and makes it sente? Hyperpape

Bill: Playing a gote with sente generally means that the opponent made a mistake. That's why you make a profit for free. Sometimes it refers to a so-called double sente, where one player makes a very large gote by comparison with the rest of the board and then the next largest move is the reply to it. Sometimes it just refers to a situation like this one:

[Diagram]
Gote gains something  

W1 is a gote that gains 7/8 point. Often the next largest play will be B2, which gains 3/4 point. You can half-jokingly say that W1 gained 1/8 point in sente. ;)


Double sente gain discussion


[1] Sometimes making a sente play gains because your opponent does not reply. For instance, he may ignore a ko threat. That is not what this proverb is about.

[2] On occasion, you should play sente and take a loss. For instance, it may be worth it to play a losing ko threat. Or it may be best to take a loss to prevent your opponent from taking the local play when you give up sente.


Dieter: I object to this page. It confines the concept of sente to what it means in the endgame. It is not true that sente moves keep their value whatever is done on the rest of the board. order of play is important and there are numerous examples of forcing moves that are played before the shape of a position is settled.

Bill: It's a proverb, Dieter. It does only apply to one sense of sente, but such sente moves are not confined to the endgame. Are there sente plays that gain points? Sure, but they are gote plays from a different perspective. More about this on Does kikashi gain nothing

Leo: So as far as I can tell, "Sente gains nothing" means "before it gets played, you should already be counting as if it had been played, so it shouldn't affect your appraisal of what the final score will be"? Does it also mean "the player who keeps sente keeps things proceeding the way they already are, and so only the player who accepts gote needs to reassess their situation"?


(Added from Sente Gote)

Q: How many points does playing a sente-gote in sente gain?

A: None!

(On average.)

Playing the reverse sente gains the size of the play, but all playing the sente in sente gains is preventing the reverse sente. As a rule, that will be possible, until the temperature drops to the size of the play. (That's why we measure the size of a sente-gote by the size of the reverse sente. It tells us how urgent the play is.)

Playing the sente is like cashing a check before it expires.

(In exceptional cases you play the sente because your opponent will not answer it {see tedomari}, but then you are not playing it in sente. ;-))

Because you do not gain points by playing the sente, when you are estimating territory you assume that sente plays are made and answered.


From a strictly game theoretic point of view, NO PLAY gains anything. The reason is that the value of the position before you make the play is given as the value after the following best move is made. So, you can only change the value of a position by making suboptimal plays that give away points.

  --Fredrik

Bill: It depends upon your game theory. :) If the definition of the value of a position depends upon whose move it is, then you are right. But if the value does not depend upon whose move it is, as in Combinatorial Game Theory, then moves can gain something. :)

TsuQ: The concept of what constitutes a position often depends on whose move it is, such as in the AGA superko rules. In that case a position would only exist relative to who is to move. If it mattered whose move it was, and thus it was possible to gain something from playing a move if you were considering the position separate from the move, it seems to me that position couldn't have a value - its value would be contingent upon whose move it was.


This page needs wiki master editing.



Paths: <= Endgame =>   ·   <= Go Proverbs =>
Sente gains nothing last edited by 193.1.212.124 on September 26, 2012 - 17:48
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