Go
Go is played on a 
grid, with pieces being placed
at the intersections of grid lines, rather than in the middle of them. Go
boards have a number of peculiarities, including the fact that the aspect ratio is
approximately 0.91 (instead of the usual unity for western games). This is done so
that with perspective, the board appears square. Another is that go pieces (called
stones) are actually slightly larger than the spacing on the board allows, thus requiring
stones to be placed partially underneath one another to fit, producing a state of
mild disorder on a full board.
Go is played by players alternately placing stones on the board, with one player using white stones and the other black stones. There are several sets of rules (Japanese and Chinese) as to how play progresses and scoring is done, but the basic object is to surround as much "territory" as possible. When a group of one player's stones are completely surrounded the other player's (i.e., there are no holes and the stones of one color have stones of the other color adjacent to each possible location horizontally and vertically), the surrounded stones are "captured" by the other player. Go has a number of special terms to refer to specific board configurations, including "atari."
Sensei's Library provides a large collection of go resources, including extensive links to additional material.
The images above show an empty go board and a go board near the end of a game.
There are estimated to be about 
possible positions
on a 
board (Beeler et al. 1972, Flammenkamp).
The number of 
-move go games are 1, 362, 130683, 47046242, ...
(OEIS A007565).
Contact the MathWorld Team
go
