In this section, we are going to have a quick overview of what is the game of Go and how we play it.
The game of Go is a two players game (Black and White). Each player controls an army of his color. At the beginning, the board is empty. The main goal of the game is to control the biggest territory at the end of the game. To achieve this, each turn, the two players have to put one stone of his color on the board (goban). Once put on the board, a stone can not be moved, unless it is captured. The end of the game occurs when both players have passed consecutively.
The Board of the game of Go is named goban. It is composed by 19 by 19 intersections in the regular size. But it exists other sizes like 13x13 or 9x9 for quick games. For our purpose, we are going to consider only games on 9x9 board size. A stone can only be played on an empty intersection. In case of significant level between the two players, the weakest player (Black) is allowed to put N stones on the board before the very first move of the White player. These stones are usualy placed on Hoshi intersection that corresponds to strategically-important intersections of the board (marked with small dots).
Two stones of the same colors that are adjacent are linked together and form a group. A group can not be subdivised. By commodity, we can consider that a stone alone form a group of one stone. We define the liberties of a group the total number of free adjacent intersections. At any state of the game, if a group of stones has no liberties, then this group is captured by the opponent. The only exception of this rule occurs when a group suppresses his last liberty in order to captured opponent stones.
End of the game
At the end of the game, both players sum the total of free intersections that are surrounded by their stones. The winner is the one who got the biggest control of the board