Hypothetical Play

Hypothetical play is one way of settling disputes at the end of the game when players agree that the game is finished (usually by two successive passes), but then disagree on the life and death status of stones. In such a situation, “hypothetical play” means

following description subject to approval by rules experts

that the players, possibly with the help of an official or expert, discuss their reasons for considering stones alive or dead until they reach agreement.

The term “hypothetical play” refers to the way such discussions tend to take the form “if Black plays ``A``, White can play ``B`` … so the status is ``S``”.

A special case arises when the players conclude that a group or semeai is unsettled, i.e. that the next player to move could settle it in their favour. Both players may feel that its status should be decided in their favour. In fact

{what happens: seki with no points in any unsettle groups? alive? dead? as if first player to pass were to continue? varies per rule set?}

Once they agree on the status of all stones, scoring continues as usual according to the rules in force as applied to the final game position (after both passed).

In practice, some (especially weaker) players may play out sequences on the board and then (try to) re-establish the final game position, but this introduces a risk of errors when playing with a physical board and stones.

Hypothetical play differs from an encore (another way of settling disputes) in that the board position remains as it was when the players passed, whereas in an encore play continues under special rules.

Hypothetical play is used by {to be added: rule sets that use it}.

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Bill: The Japanese 1989 rules do not themselves refer to hypothetical play. However, they do require confirmation of the life and death status of stones after play stops. The rules also allow for resumption of play, so confirmation does not allow actual play. However, the rules for kos is different in confirmation from the rules of kos in actual play. So confirmation implies the use of hypothetical play to determine life and death.

See also

• Encore — A phase of play after play resumes.
• {do we have other articles providing some crucial or helpful details?}