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JAPANESE 2003 rules - COMMENTARY - INFORMAL
NEW AMATEUR-JAPANESE rules - COMMENTARY

Japanese 2003 Rules
Version 35a


Axioms

There are Black and White.

There are stones.

There are lines.

Definitions 1

A player is one of Black and White.

A black-stone / white-stone is a stone of Black / White.

The grid consists of 19 horizontal and 19 vertical lines.

An intersection is a place of the grid where a horizontal line meets a vertical line.

Two intersections are adjacent if there is a line but no third intersection between them.

A position is the distribution of black-stones and white-stones on the grid's specific intersections.

A black-string / white-string is an intersection with a black-stone / white-stone on and, recursively, any adjacent intersection with a black-stone / white-stone on.

A string is either a black-string or a white-string.

A liberty of a string is an empty intersection adjacent to at least one of the string's intersections.

Move

A play

A pass is announced as "pass".

A move is either a play or a pass.

Alternating-sequence

The alternating-sequence is a sequence of moves that

Definitions 2

The final-position is the position just after the alternating-sequence's ending pass.

A final-string is a string in the final-position.

A ko consists of two adjacent intersections so that a play on one of them succeeded by a play on the other one would recreate the position.

A ko-stone is a string on one intersection of a ko.

A ko-capture is a play that is in a ko and removes exactly one stone.

A ko-pass by a player is announced as "ko-pass" if a ko-capture by the player in some ko is currently available but prohibited.

A hypothetical-move is either a play, a ko-pass, or a pass.

Hypothetical-sequence and Hypothetical-strategy

For a given player, a hypothetical-sequence is an imagined sequence of hypothetical-moves that

A left-part of a hypothetical-sequence is either the whole hypothetical-sequence or a part that consists of one or more than one successive hypothetical-moves of it and starts with its first hypothetical-move.

A player's hypothetical-strategy is a set of one or more than one left-parts of hypothetical-sequences so that

A hypothetical-sequence is compatible with a hypothetical-strategy of a player if each left-part that is of the hypothetical-sequence and ends with a hypothetical-move of the player is in the hypothetical-strategy.

A player can force something if there is at least one hypothetical-strategy of his so that each compatible hypothetical-sequence fulfils that something.

Life and Death

A player's final-string is uncapturable if the opponent cannot force capture of its stones.

A permanent-stone is a stone that is played during a hypothetical-sequence and then not removed during the rest of the hypothetical-sequence.

For a final-string, local-1 is all the string's intersections.

A player's final-string is capturable-1 if

For a player's final-string, local-2 is local-1 and, recursively, any adjacent intersection without a stone of a string that is of the player and either uncapturable or capturable-1.

A player's final-string is capturable-2 if

For a final-string, local-3 is local-1 and, recursively, any adjacent intersection without a stone of a string that is either uncapturable or capturable-1.

A final-string is capturable-3 if

A final-string is alive if it is either A final-string is dead unless it is alive.

Hypothetical-analysis

The hypothetical-analysis assigns either alive or dead to each final-string.

Definitions 3

In the final-position, a black-eye-string / white-eye-string is an intersection that is empty and, recursively, any adjacent intersection that is empty or occupied by a stone of a dead white-string / black-string.

In the final-position, an intersection of a black-eye-string / white-eye-string is a black-eye-point / white-eye-point if the black-eye-string / white-eye-string is adjacent and only adjacent to intersections with stones of one or more than one alive black-strings / white-strings.

In the final-position, an eye-point is either a black-eye-point or a white-eye-point.

In the final-position, a dame is an empty intersection that is not an eye-point.

In the final-position, a black-region / white-region is an intersection with a stone of an alive black-string / white-string and, recursively, any adjacent intersection that has a stone of an alive black-string / white-string or is a black-eye-point / white-eye-point.

In the final-position, a black-region / white-region is in-seki if at least one of its intersections is adjacent to a dame.

In the final-position, an intersection is black-territory / white-territory if it is a black-eye-point / white-eye-point that is not part of an in-seki black-region / white-region.

The prisoner-difference is the number of white-stones minus the number of black-stones that are removed during the alternating-sequence.

In the final-position, the score is

Result

The result is

Game

The game consists of the following in the given order:


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