The Complete Rules of Go
Go is played by two players. Each has a supply of stones of one color.
is a small, round, hard playing piece of a single color, either black or white.
Stones are made of glass, seashell, slate, or plastic.
Play proceeds on a board containing a square grid of black lines. Common
grid sizes are 6x6 (or 7x7) (for learning the rules), 9x9 and 13x13 (for quick
games), and the standard pattern of 19x19 lines.
Players alternate making moves.
consists of placing a stone of the player's color on the board, possibly
capturing opponent's stones.
Either player may
at their turn instead of placing a stone. When players believe that the game is
over, they pass. Players should not pass if they believe that the score can be
changed by further play.
The player with black stones plays first. Usually the stronger player takes
Stones are played on intersections, including the intersections at the edge and
the board's grid.
Stones do not move after being played.
is an initial pattern of black stones granted to a player of lesser rank.
Handicaps permit players of unequal rank
to play each other. Handicaps are placed in specific patterns, starting with
the intersections that are marked with small black dots.
After the handicap stones are placed on the board, white moves first.
is an optional number of points added to white's score to compensate
for the fact that black moved first. On a 9x9 board, komi is usually 6.5
points; on 19x19 it is usually
5.5 points. The half point guarantees that games will not end in a draw (tie).
The value of komi results from the fact that one stone played at the start of
a game on a 19x19 board is worth approximately
10 points by the end of the game, assuming that the players play well and have
a small difference in rank.
when both players agree that they can make no move that increases their score.
This agreement is indicated by two successive passes.
of stones are one or more stones of one color that are all touching (adjacent)
and 'joined' to each other by horizontal or vertical lines on the board
(diagonals do not
join stones to form strings).
The empty adjacent intersections of a string are called the string's
If the number of liberties of a string is one, the stones are said to be in
and will be captured whenever the opponent places a stone so as to change the
number of liberties to zero.
A stone may not be placed on the board if it would then have zero liberties,
when it captures opponent strings. This is known as the
of stones are strings of the same color that are 'connected' to
each other by short, non-adjacent gaps. Usually, but not always, only the
following kinds of connection are allowed when defining a group: diagonal,
single-point skip, double-point skip, small knight's move, and large knight's
move (the latter two terms derive from chess).
Strings of stones are
by either player whose move causes one or more
opponent strings to have zero liberties. The opponent strings must be removed
from the board immediately and their stones are counted as prisoners of the
the move that captured the strings. The capturing stone remains on the board.
Note that a group that surrounds two or more nonadjacent empty points (such
points are called
cannot be captured, because a player cannot play in both points in one
move (the player
cannot play in either empty point in one move because of the rule of no
self-capture). A group that cannot be captured is called a
A group that can be captured (that is, does not have the possibility to form
two eyes) is called a
. A dead group cannot gain life unless surrounding opponent stones are
The rule of
prohibits any move that would cause any previous board position
(pattern of stones) to be repeated. This rule applies to a situation where
the same strings could otherwise continue forever.
Seki (dual life)
is the situation in adjacent groups of stones where both players do
not want to move because any move would place their own strings in atari.
Such stones are left on the board and are ignored during scoring.
A game is scored at the end of the game and the player with the higher score
wins. There are a number of different sets of rules for scoring, including
American, Japanese, Korean, and Chinese. The scoring rules
described here are the most common rules for informal play, a simplification of
the Japanese rules.
consists of all empty points that are completely surrounded
by stones of the player's color. The surrounding stones need not belong to the
same string. For the purpose of counting territory, edge lines act like stones.
Empty points that are surrounded by stones of both colors are called
not define territory and are ignored during scoring. Empty points inside groups
in seki are not counted, even though they may be surrounded by
stones of the same color.
Before scoring, dead stones are usually removed from the board, to become
prisoners as though they had been captured in the usual way. This simplifies
scoring. Some players like to rearrange the remaining stones so as to make all
territory form rectangular areas, for ease of counting the points of territory.
for a player is the total of the player's points of territory and prisoners.
Players have levels of play called
(ranking, rating). Two players whose rank differs by
two points, for example, tend to win the same number of 19x19 games with each
when the weaker player starts with a handicap of two points, and so on for
larger differences in rank. Ranks are a scale that starts at about
for newcomers to the game and decreases with improvement in play until it
reaches one kyu. After that it continues at one
and increases up to a current maximum of about 9 dan. These are sometimes
players usually have a strength level greater than this; their rank is on
another 'dan' scale that starts at one dan/professional (1p) and increases to
about 9 dan/professional.
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