Simplified Ing Rules

Simplified Ing Rules - Summary

Move: A move is either a play or a pass.
Suicide: A play may remove one's own stones.
No Repetition: A play may not recreate a previous position.
Stop: Alternate moving stops with two successive passes.
Agreement: After the first stop, the players may 1) agree about all regions that shall be removed, remove them, and determine the scores or 2) disagree, resume alternate moving, and determine the scores immediately after the second stop.
Score: A player's score is the number of all his empty or occupied intersections.
Result: The player with the greater score wins, unless the game is a tie because the two scores are equal.

Simplified Ing Rules - EGF Rules Text

General

Two players play the game with stones and a board. One player uses black stones, the other white. The board is a grid of lines and their intersections.
As a default, the game starts from the empty board that is a grid of 19 horizontal and 19 vertical lines forming 361 intersections.
Two intersections can be adjacent along a line.
Stones of the same colour are connected if they are adjacent or if there is a chain of adjacent stones of their colour between them. Likewise, empty intersections are connected if they are adjacent or if there is a chain of adjacent empty intersections between them.
A region consists of an intersection and any intersections connected to it.
The position is the distribution of black, white, and no stones on all the unique intersections of the grid. For a play, this is given after all its removals.
The score of each player is the number of all intersections a) with stones of his colour, and b) of the empty regions that are adjacent only to intersections with stones of his colour.

Move

The players move alternately. Black moves first.
A move is either a play of one's own stone on an empty intersection, or a pass.
A play removes stones of every region without adjacent empty intersection. Removing opposing regions takes precedence over removing own regions.

No Repetition

A play may not recreate a previous position from the game.

Agreement

Alternate moving stops with two successive passes.
Then the players may make an agreement about all regions that shall be removed.
If they agree, they remove those regions and determine the scores.
If they disagree until the result is fixed, alternate moving continues as if there had been no removals due to agreements. Then immediately after the next two successive passes, they determine the scores.

Result

For the final position, either the scores are unequal and the winner is the player with the greater score or the scores are equal and the game is a tie. The players fix this as the result.

Simplified Ing Rules - Commentary

General

Purpose: The Simplified Ing Rules are used in those EGF tournaments that are said to use Ing Rules. Since official Ing Rules have too difficult and equivocal texts, the Simplified Ing Rules override those.
Wording: The wording is derived from the International Rules of the mailing list "go-rules", simplifies some general definitions, is more precise, and is adapted for the particular purpose of simplifying Ing rules in EGF tournaments.
Differences: In rare situations involving ko or passes, the Simplified Ing Rules differ from official Ing Rules. This is an intended feature so that the rules can be applied not only by a few rules experts but by all players and referees, whether or not they have read their text.
Vocabulary: The vocabulary fits common usage by European players, except that it uses "region" for both strings of stones and connected empty intersections.
Default: For variants of the game, extra tournament rules can override the default settings for the initial position or the grid size.

Region

A region may consist of exactly one intersection.
There are three types of regions: a region consisting of black stones, a region consisting of white stones, an empty region.
The intersections of the region are connected along lines. A region need not have a straight appearance but it cannot be interrupted by any intersection of some other type. A region is maximal: next to a black region there is no further black intersection, next to a white region there is no further white intersection, next to an empty region there is no further empty intersection.
When a play removes a region, then this can also be called a removal of stones without any liberty.
During scoring an empty region does not provide any points if a) it is adjacent to at least one black intersection and adjacent to at least one white intersection or b) the whole board is empty.

Move

The player having the turn has the right to choose between play and pass. It is the player's right to make strategic mistakes even intentionally. The rules prescribe what is legal - they do not distinguish between good or bad strategy.
In order to pass, a player must press the clock. Thereby his opponent is informed properly and he does not need to reveal any strategic hints when trying to understand whether the player passes. If a player cannot say "pass" due to language problems, he can still press the clock.
Successive passes are used only to stop alternate moving.
A clock specified in extra tournament rules runs only during alternate moving.
Removal of one's own regions is called suicide and is legal. It can only occur if a play does not remove any opposing regions.

Superko

General: The used variant of the no repetition rule is also called "Positional Superko", is the simplest superko rule, and known to most players as "the superko rule".
Practically relevant consequences: 1) A 2-play loop is impossible. 2) Suicide of exactly one stone is impossible. 3) It depends on legal strategy whether or how bent-4, double ko, triple ko, etc. are played; e.g., in a triple ko a sequence of one play or a sequence of five successive plays often have the same strategic effect.
Examples of rare strategic differences to official Ing Rules: 1) Successive passes do not create an exception to superko. 2) Two so called disturbing life patterns each with two 2-play kos on the board or 3) a triple ko with one eye, two so called internal 2-play kos, and one so called external 2-play ko are treated by superko like any other shape.
Examples of scarce technical differences to official Ing Rules: Although hardly a strategic issue, sequences of legal plays within scarce kos can differ, e.g., in a triple ko five successive removals can be possible with the Simplified Ing Rules but not with official Ing Rules.
Disagreement: If after the first succession of two passes the players disagree about removals, then removals are restored and do not effect superko for continued alternate moving since the rule about a continuation due to a disagreement relies on the assumption that there would have been no removals due to agreements. Before a continuation, all premature removals are undone.

Agreement

It is the right of a player to choose whether regions that can be removed are removed by actual plays before the first succession of passes, by means of the players' agreement after the first succession of passes, or by continued alternate moving until the second succession of passes.
It is the right of a player to agree or to disagree on removals. Extra tournament rules cannot restrict that right.
After the first succession of passes, before the result is fixed, and before any continued alternate moving, it is always the right of a player to request continued alternate moving. The condition about the "fixed result" allows to make and correct counting mistakes for determination of the scores; however, once the result is fixed, it is not possible any longer to resume alternate moving.
In case of agreement, a game has exactly one succession of two passes.
In case of disagreement, a game has exactly two successions of two passes and has an immediate determination of the scores after the second succession. Continued alternate moving starts from the position at the moment between the previous two successive passes and with the opponent of the last passing player. During continued alternate moving, a move is either a play or a pass, as usual. In particular, the entire continued alternate moving might consist of exactly two moves that are both passes.

Result

Extra tournament rules might set compensation points (komi) and shift the scores accordingly.
In practice, a score can be determined by a mechanical counting procedure. In tournaments with Ing sponsorship, fill-in counting is recommended. Then, e.g., 4 white stones can represent a komi of 7.5 or 8.
Extra tournament rules may require that the result be fixed by letting both players sign a result form or make verbal statements.
Extra tournament rules may specify resignation.