[Welcome to Sensei's Library!]

StartingPoints
ReferenceSection
About


Paths
Endgame

Referenced by
SenteGettingTesuji
Zokusuji
Clamp

 

Endgame Clamp
Path: Endgame   · Prev: MonkeyJump   · Next: EndgameConnectOrNot
    Keywords: EndGame

The Endgame Clamp

[Diagram]
Diag.: Black to play

How should Black play for the greatest endgame profit? Is it the monkey jump, or what?


[Diagram]
Diag.: Using the monkey jump

We shall try the monkey jump... looks fairly good, doesn't it?

For details, please go to the monkey jump page.


[Diagram]
Diag.: Using the endgame clamp

Now we shall see the endgame clamp at 1.


[Diagram]
Diag.: Using the endgame clamp

White responds with 2, and the result up to 8. Which is better?

Comparing the monkey jump and the endgame clamp diagrams:

  • In the monkey jump diagram, White has one extra point of territory at a.
  • In the endgame clamp diagram, Black has one extra point of territory at b.

So, we conclude that the endgame clamp is two points better than the monkey jump for Black.

--unkx80



[Diagram]
Diag.: Variation

How about White 4 ? DieterVerhofstadt


[Diagram]
Diag.: Continuation

One point better for Black, but White has sente. But of course, if Black leaves 7-8-9 unplayed, then he can come back to take two points in gote later.


[Diagram]
Diag.: Counting value

unkx80: I shall count the value of the sequence up to White 6, assuming that the territories are defined by the marked stones.

Comparing it with the endgame clamp diagram, White has one extra point of territory but Black has captured one more stone than White.

The value of White 4 in this variation is the same as the one shown in the endgame clamp diagram. :)

BillSpight: Indeed that is so. :-) It might be interesting to compare it with the solid connection in a DifferenceGame: ClampConnectionComparison.



[Diagram]
Diag.: Overdoing it.

It's interesting to note that this Black 1, which seems more severe, is one point worse, and loses sente!


[Diagram]
Diag.: Same result.

Black pushing at 4 instead of at 3 is one more point worse off (If I've read correctly).

--MortenPahle

DieterVerhofstadt writes: Morten, this is called synchronicity. I was about to make exactly the same comment !


[Diagram]
Diag.: Another way ?

Either Black has sente or there is an extra reduction at a, resulting in a large ko for both or another loss for White.


[Diagram]
Diag.: But ...

But White sacrifices a stone. Again: same result, one point worse off and loss of sente.

DieterVerhofstadt

The sad thing is that I would play this (and similar non-optimal moves) if this were a real-game situation.... The temptation to play something which looks bigger to begin with , although I have a nagging feeling from having seen it in a book or in a game that it is inferior.... is often too big :o(( --MortenPahle



BillSpight: Looks can deceive. The clamp is gote.

(unkx80: You are not wrong, but you have to take into account the actual situation. Most Chinese Go books written by professional players say that the clamp is sente.)

(Bill: Most Japanese go books do, too. ;-))

[Diagram]
Diag.: Gote

White 2 protects the corner. That reduces the local temperature. White should view the marked stones lightly. Later Black 5 is sente.
Later the following is Black's sente.

[Diagram]
Diag.: Sente

Black 1 is tesuji. If Black starts with Black 3, he loses sente.



[Diagram]
Diag.: still gote

MartijnWallage?, 1k: Well, if sente is so important. White can play 2 and then Black 3 is not sente anymore.
But sente can't be so important since in the "Sente" diagram Black doesn't gain anything.



Bill: Indeed, after Black 1 - White 2, Black 3 is not sente. In fact, it is ambiguous. For evaluation purposes we can treat it as White's sente.

[Diagram]
Diag.: Still sente

Black 3 elsewhere.
If we compare this with the sente diagram, we see that White is 2/3 of a point worse off here, and Black 1 - White 2 is still sente.

As for a sente not gaining anything (on average), that is the nature of a sente-gote position. :-)

How large is the sente?

[Diagram]
Diag.: Reverse sente

If White plays the reverse sente at 1, now a and b are miai. This position is 2 1/3 point better for White than if Black takes his sente, so the sente is worth 2 1/3 points.
If Black plays gote he picks up only 1 2/3 points.

So if Black does not play his sente, White will play the reverse sente (as a rule). If the ambient temperature is less than 2 1/3, that represents a loss for Black.



Path: Endgame   · Prev: MonkeyJump   · Next: EndgameConnectOrNot
This is a copy of the living page "Endgame Clamp" at Sensei's Library.
(OC) 2003 the Authors, published under the OpenContent License V1.0.