# A Problem with Hidden Move Go

I have just learned about Hidden Move Go and I have a problem.

Let us assume that one of our opponent’s hidden stones has only one liberty, i.e. it is in atari. But they don’t know that, because one of our three surrounding stones is hidden. So they play somewhere else and we play a stone filling the last liberty of their hidden stone. In this position we have no idea that we have captured a stone and our opponent has no idea that their stone is captured. Because of this, the table is wrong and it mustn’t be. How can we avoid that situation without the help of a third person? Any ideas or experiences?

• You write “the table is wrong and it mustn’t”: do you mean “the position on the board is incorrect”? Commented Oct 13, 2017 at 9:48

As I read the description in Sensei’s Library (your own link), hidden moves are not considered to be played on the board until they are revealed; you may like to think of the stone as still in a special pot with a label on it. So a not yet revealed stone cannot be captured or in atari. It can, however, be used to prevent a move your opponent tries to make.

In your example, if my interpretation is correct, the hidden stone is therefore not in atari: neither it nor your hidden stone are even on the board. You next move does not capture the hidden stone. The board (which I suppose you mean by ‘table’) is not wrong. No third person is required.

The rules are, however, not rigorously formulated, and other interpretations are conceivable.

• The hidden stones are more like ghosts, then, which "possess" any stone that would be placed there by the opponent.
– Nij
Commented Oct 13, 2017 at 21:18
• From Sensei's page: "During the game, when a hidden move would affect play, the player reveals the hidden move and places it on the board." and "Examples: White uses his own hidden stone to capture enemy stones. He reveals his hidden move, and makes his own move to complete the capture.".
– Stef
Commented May 21 at 14:46
• It seems to me that the situation is a lot more ambiguous than your answer suggests, and that in fact, the rules as described on this Sensei's page do not cover this situation at all. The implementation at go.kahv.io probably cover this situation, and probably differ from what's described on Sensei's page, and I wouldn't be surprised if your answer is in agreement with the go.kahv.io rules, although I haven't tested.
– Stef
Commented May 21 at 14:50
• I agree that the formulation there is unclear. I have edited my answer to clarify that I am merely stating how I understand the rules. It would be a service if someone could tighten this description up, perhaps with reference to go.kahv.io. Commented May 21 at 18:34
• Well, of course an online implementation won't run into problems, because there is always an external entity - the server - which knows where both players' hidden stones are. Commented May 21 at 19:45