Position

    Keywords: Rules, Go term

A position is the arrangement of black and white stones on the go board. Position is a term used in different contexts, like positional judgement or the restriction for repetition of a position in superko rules.

The term position may also be used to refer to the distribution of stones on a specific region of the board. To avoid ambiguity one may refer to a local position or a whole board position, where appropriate (as in a superko rule).

Formal Definition

Given a grid graph? G = (V, E), the position consists of the color information of all vertices (intersections), where the color can be "black", "white", or "empty".

A position can either be legal or illegal. A position is legal if and only if no strings of stones that have no liberties exist.

Number of positions

On the 19×19 board, there are 361 intersections. Since each of these can be either black, white, or empty, there are 3^361 (about 10^172) possible positions on that board. Not all of them are legal. Research by John Tromp and Gunnar Farnebäck has shown that approximately 1.2% of board positions are legal (no stones without liberties exist on the board), which makes for about 10^170 legal positions. See also: Number of possible go games.

Example

[Diagram]

An example position after 9 moves of play


Compare situation.


This is a copy of the living page "Position" at Sensei's Library.
(OC) 2011 the Authors, published under the OpenContent License V1.0.
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