Area scoring (including Chinese):
A player's score is the number of stones they have on the board, plus the number of empty intersections surrounded by that player's stones.
Comparison of the scoring methods:
Given that the number of stones a player has on the board is related to the number of prisoners the opponent has taken, the resulting net score (the difference between Black and White's respective scores) under both rulesets is often identical and rarely differs by more than a point.[13]
Each of these scoring methods has advantages and disadvantages.[14] There have been some efforts to agree on a standardized set of international rules. Those rules with a degree of recognition from the International Go Federation include the rules of the World Amateur Go Championship, based on the Japanese rules, and those of the First World Mind Sports Games of October 2008, essentially based on the Chinese rules with some compromise elements towards the Japanese and Korean rules.
Life and death
While not actually mentioned in the rules of Go (at least in simpler rule sets, such as those of New Zealand and the US), the concept of a living group of stones is necessary for a practical understanding of the game.
When a group of stones is mostly surrounded and has no options to connect with friendly stones elsewhere, the status of the group is either alive, dead or unsettled. A group of stones is said to be alive if it cannot be captured, even if the opponent is allowed to move first. Conversely, a group of stones is said to be dead if it cannot avoid capture, even if the owner of the group is allowed the first move. If the status of a group depends on whether the owner or their opponent moves first, the group is said to be unsettled. In such a situation, the player that moves first may either make it alive if they are the owner, or kill it if it is the opponent's group.
For a group to be alive, it needs to be able to create at least two eyes if threatened. An eye is an empty point that is surrounded by friendly stones and where the opponent can never play due to the suicide rule. If two such eyes exist, the opponent can never capture a group of stones, because it will always have at least two liberties. One eye is not enough for life, because a point that would normally be suicide may be played upon if doing so fills the last liberty of opposing stones, thereby capturing those stones. In the "Examples of eyes" diagram, all the circled points are eyes. The two black groups in the upper corners are alive, as both have at least two eyes. The groups in the lower corners are dead, as both have only one eye. The group in the lower left may seem to have two eyes, but the surrounded empty point without a circle is not actually an eye. White can play there and take a black stone. Such a point is often called a false eye.[15]
There is a rare exception to the requirement that a group must have two eyes to be alive, a situation called seki (or mutual life). Where different coloured groups are adjacent and share liberties, the situation may reach a position when neither player wants to move first, because doing so would allow the opponent to capture; such situations therefore remain on the board.[nb 4] Sekis can occur in many ways. The simplest are: (1) each player has a group without eyes and they share two liberties, and (2) each player has a group with one eye and they share one more liberty. In the "Example of seki (mutual life)" diagram, the circled points are liberties shared by both a black and a white group. Neither player wants to play on a circled point, because doing so would allow the opponent to capture. All the other groups in this example, both black and white, are alive with at least two eyes. Sekis are unusual, and usually result from an attempt by one player to invade and kill a nearly settled group of the other player.[15]
