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Ambiguous Position
   

The OngoingGame has a position that, with a couple of changes, is ambiguous whether it is sente or gote.


[Diagram]
Diag.: Either Sente or Gote?

Black has a 1 point gote (MiaiCounting) with B a - W b, B c, or a 1-point sente with B c - W a.

It is not unusual to have both sente and gote options in a position, but we typically consider a position to be sente or gote according to the largest option. Here they are the same size, and the position is ambiguous.

Not sure if I can follow your counting here. If B plays c, then W will get the additional point at b, since in the given position, there's no need to defend further. Consequently, if the gote move is considered worth 1 point for B, then the sente move is worth zero (ignoring the reverse gote possibility for w, of course). --GeorgMischler 2k

Let's normalize the count, so that the result if Black plays 'c' and White plays 'a' is 0. Then we may represent the position like this:

          {{Big | 0}, 1 | -1}

("Big" means big enough for sente. Here it is more than 5, I think. Negative numbers are White scores. Positions or scores to the left of the bar are reached by Black moves, those to the right are reached by White moves.)

          {1 | -1}

is a 1 point gote.

           {{Big | 0} | -1}

is a 1 point sente.

Make sense?

-- Bill

Assuming that I understand your notation correctly: If the {{Big | 0} | -1} is meant to be one point sente (0 - -1 = 1), then {1 | -1} still looks a two point sente to me in comparison (1 - -1 = 2). Please don't get me wrong, I really like the discussion about chosing the "right" move here, especially considering the (still sente!) "Big" follow-up. I just don't see the ambiguity. Or maybe my real world understanding of the term "ambiguity" is too narrow to be applied here. Now if we could determine the exact point value of getting sente, things might become much more obvious... --GeorgMischler

Sorry. I have amended the original to state that I am using miai counting. That's the one to use when comparing plays. You are using deiri counting, which is more common. The rule for comparing deiri plays is to multiply sente values by 2 (or, equivalently, to divide gote values by 2, which gives you miai values). So the 2-point gote and the 1-point sente are the same size.

-- Bill

Ah well, even I can understand it if you explain it this way! ;-) --GeorgMischler
(PS: Maybe this difference between the value of sente and gote moves should be explicitly mentioned in MiaiCounting then?)



Here is another kind of ambiguous position:


[Diagram]
Diag.: Neither/nor ?

This play is worth 3 points. If White saves one stone, there is another 3 point play left.

This isn't exactly sente, because White cannot normally make the play at a time when Black cannot afford to play here instead. But it isn't exactly gote, either, because White will normally make the play when Black's reply will be the largest play on the board. It's ambiguous.

-- BillSpight



This is a copy of the living page "Ambiguous Position" at Sensei's Library.
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