Go - unity in diversity

Tao gives birth to one, one gives birth to two,
two give birth to three, and three - all things ...

Lao Zi "Tao Te Ching"

Let a hundred flowers bloom
let a hundred schools compete.
')
Qin Shi Huang

Guo rules are simple, but simplicity ends where the scoring begins. There are many really difficult situations, logically arising from very simple rules. I want to talk about the reasons for which there is no single method of counting points in Go. The reasons for which there are many different versions of the rules of this game.

Stumbling block

Perhaps the main source of disagreement is the question of what should be considered “victory points”? By and large, there are two approaches: in the Japanese variant of the rules, the total number of points of the territory and the captured stones of the enemy are used, in Chinese - the area captured by the player. Here it should be explained how the territory differs from the area .

The player’s territory is called the free points of the board, from which, following only vertical and horizontal connections, it is impossible to reach the opponent’s stones. In the picture to the left, the points of the black territory are marked with triangles. In turn, the area captured by the player, in addition to the territory, includes all the points on which the stones belonging to the player are installed.

It is important to understand that both the territory and the area are calculated after the removal of all the “dead” groups from the board. For each group located on the territory of the enemy, its status is determined. So, for example, groups with “two eyes” are recognized as “alive” and remain on the board, enclosing their own territory. Groups of stones that can be captured when playing the game are recognized as “dead” and removed from the board (in the Japanese version of the rules, stones removed from the board are added to the stones captured by the enemy).


The figure shows the result of the position estimation by the KGS server (when playing by the Japanese rules). Captured stones are shown in a translucent color. The result of the game is determined by the ratio of the number of points of the territory, marked on the figure with small stones (including, under the "dead" stones). It can be noted that part of the free points is not included in the territory for any of the players. Such items (from which you can get to the stones of different colors) are called “neutral” or dame .

Obviously, when using the Chinese version of the rules, neutral points can bring additional points as they increase the area captured by the player. In this regard, the game, according to this version of the rules, provides for the players to fill in all the neutral points in turn, before the game ends. If a player misses a move without filling the remaining neutral point of the board, this item will be captured by the opponent (as a result, the latter will receive an additional point, possibly determining the outcome of the game).

The process of mandatory filling of neutral points can be a problem when playing with time control in the Penalty Point system (PP). When using this agreement, each player who has exceeded the limit of the main time, penalty points are added. There may simply not be enough time to fill all neutral points (or their filling will become unprofitable due to fines). The Second Reading (RS) system is devoid of this disadvantage. At the end of normal time, the player is allocated a small period of time for each move ( bye-bye ), which is quite enough to complete the moves that do not require prolonged deliberation. The total time of the game, in this mode, is not limited. Fixed only the number of time intervals that are allowed to exceed.

When playing by the Japanese rules, it becomes unprofitable for the player to “finish off” the dead groups on its territory. In fact, “killing” such a group, in itself, will not add points, but you will have to spend at least one point of your territory in order to pick up the group. Equally unprofitable are defensive structures, but in this respect it is important to keep a balance - if the enemy manages to invade and build a “live” group, the losses will be much greater.

An important disadvantage of the Japanese version of the rules is the possibility of cheating when scoring points. Correctly counting the territory, at the end of the game, is not easy, so there is a technique to simplify the counting. Immediately after removing the "dead" groups from the board, the players expose all the captured stones to the enemy’s territory, reducing it in this way. After that, the stones, inside the territories, are usually moved, to facilitate counting.

In the wonderful series " Hikaru no Go " there is a magnificent illustration of how, using this procedure (and a little manual dexterity), you can slightly increase your territory at the expense of the enemy's territory. Another possibility is to toss extra stones to the number taken. Hikaru no Go also illustrates this point .

Neither life nor death

As I have already said, before the scoring, “dead” groups are removed from the board. Unfortunately, the status of the group is not always determined unequivocally. This book provides an example of a party, during which a “live” form with two “false eyes” was formed. The figure on the right shows how black can build such a form. If blacks did not connect, surrounding whites, both eyes would be “false.” Guo does not tolerate dogma. As soon as we formalize some kind of observation, introducing simplifications into the real “picture of the world”, this game immediately gives us a surprise. Each form must be considered individually. Various rules of thumb help to play Go better, but are not “ultimate truth”.

Often, the question of "life and death" depends on the order of the course, and this fact is another reason for the emergence of discrepancies in the rules. According to the Chinese rules, “playing out” the controversial positions is carried out without changing the sequence of the move, being, in fact, a continuation of the game. In the Japanese version of the rules, the status of each group is determined separately. The first move, however, is always performed by the player defending the group.

The dependence of “life and death” of groups on the sequence of a move is in itself a problem that can lead to disagreements in determining the winner (especially in the Japanese version of the rules), but this is only part of the trouble. In some positions, groups are neither “alive” nor “dead.” This situation is called " seki ", but before talking about it, you should talk about " same ".



In this position, the winner is the player who managed to surround the first group of the enemy. The outcome of the struggle depends on the sequence of the move, since the number of "breathing points" of both groups is the same. Sameey situations are quite common in the game and it is important to be able to distinguish them from hopeless positions.

This position is more interesting. Regardless of the succession of the move, the player who attacked the opponent's group gets into the position of damazumari (lack of “breathing points” in the group). The next move, the enemy destroys his group. Thus, it is unprofitable for any player to start the fight. This is one of the possible variants of seki (a situation where none of the groups can “kill” the other). More complex seki examples are covered here .

Points of territory surrounded by groups in the state of seki are another cause for disagreement. According to the Japanese rules, they are not counted. In the old version of the “ Inga rules, ” introduced in order to rationalize and unify the Go rules, it was proposed to divide the territory seized in the seks between the players, in proportion to the number of stones surrounding it. Unfortunately, this rule significantly complicated the scoring procedure. Since 1991, according to the rules of Inga, only the points of the territory in the seki , completely surrounded by any one color, are taken into account.

One of the consequences of using the Japanese points scoring system is that the well-known positions of "life and death" are rarely played out to the end. Japanese rules stipulate a number of special cases governing the consideration of such positions. One notable example is the position of the position of Magari Simoku in the corner of the board. In the center of the board, this four-point territory configuration is certainly alive, but in the corner there are different rules:



In this position, only blacks can start Ko-wrestling , and if there are no Ko-threats on the board, they will also win this fight. According to the Japanese rules, in the absence of Co-threats on the board (such as seki , for example), the white group, in this position, is considered dead. Such a "system of precedents" simplifies the analysis of the position in the EU , but it does not help much in cases not specified to it. Japanese rules allow judges to intervene to resolve such conflict situations, but rule systems that try to minimize judicial interference (such as the Inga system ) always play back.

The benefits of useless

Here is another dogma that can be questioned - "suicidal moves are prohibited." And according to the Japanese and Chinese rules, it is forbidden to perform moves that take the last dame from a group of its color. This prohibition is the basis of the rules of Guo, and indeed, such moves may seem meaningless. In fact, who may need to destroy their own group? In fact, everything is not so simple.



In this position, whites feel quite comfortable. They can take two black stones at any time, forming a group with two “eyes”. But what happens if black is allowed to destroy his group?



Whites are obliged to react to this move! Otherwise, their group can be destroyed by black. This means that a seemingly useless move could well be used as a threat in the Co-fight. But more difficult situations are possible. In some cases, by donating a small group, the player gets the opportunity to ensure the life of a larger group! Consider the following position:



If the “suicidal” moves are forbidden, the fate of the blacks is sad. Whites overtake them in the same and take all the stones. Everything changes, if you allow black to destroy a group of four stones:



Black can bring the position into a state of seki and, therefore, save the life of his group (although without receiving points for its territory). Such situations are rare, but it is a question of principle! If a move can affect the status of a group's “life and death”, it is not useless. Ing believes the ban on “suicidal” moves is redundant, even for groups of one stone. In fact, when playing by the Chinese rules, a player, having performed such a move, does not change position, but simply transfers the move to another player. Such an action is tantamount to a pass — a move allowed in Go.

Gaze into the abyss

Ko , of course, is the most complex concept in the rules of Go. Why is this question important? Why should players persist, repeating the moves that lead to an infinite loop over and over again? Why not go elsewhere on the board? Just because it is unprofitable. Often, the status of the “life and death” of a large group of stones depends on the outcome of the Co-struggle. The prohibition of the repetition of the position forces one of the players to break out of the "vicious circle", making perhaps a less profitable, but allowed by the rules move. Thus, a greater tactical variety is brought into the game.

The prohibition of the repetition of the immediately preceding position is easily realized and makes it impossible to form short two-way cycles in the game. Unfortunately, this is not enough to solve the problem. The presence on the board of several forms of "short Co." makes it easy to get longer cycles:



Similar situations of double, triple (and so on) Ko occur in real batches quite rarely, but there is nothing supernatural in their occurrence. Another, relatively frequently occurring position of the “Long Co.” is the situation of “ Eternal Life ”:



It is not profitable for any of the players to deviate from this sequence of moves, as a result, the game can continue indefinitely. Obviously, you need to tighten the rule Ko! The “superco” rule can be formulated in two different ways:

• Positional Superco - an unconditional prohibition on the repetition of positions, without taking into account the sequence of the move
• Super Situational Situation - prohibiting repetition of a position, provided that the turn of the same player turns

Obviously, in the first of these cases, it is required to introduce an exception for a single pass, after which the position is also repeated. Superco rule can be easily implemented in computer programs, but in tournament games, players must follow the possible repetition of the position. Different variants of the rules relate to the repetition of positions in different ways. In amateur games, such a result is usually equated with a draw; in professional games, the game is replayed.

In the rules, Inga attempted formalization, dividing the company into “combat” (connected with solving the issues of “life and death”) and “troubling” (absolutely forbidden in the game), but it can hardly be called successful. To understand the rules of Ko, in this interpretation, a sufficiently high qualification of players is required. In the Inga simplified rules, the “positional superko” rule is used.

The end and the beginning

To complete the picture, it remains to consider issues related to the beginning and end of the game. The Guo game is traditionally completed with two successive players. Such a sequence of moves means that no player sees a way to improve the position. The following is the determination of the status of the disputed groups and the scoring. The devil, as always, is in the details.

In 2002, during the European Championship in Zagreb, a conflict arose related to the insufficiently clear definition of the order of completion of the game according to the rules of Inga. One of the players demanded the removal of an unconditionally “dead” group from the board, after the formal completion of the group status process (the second pair of passes). The referee's decision was made in favor of this player, but the very intervention of the judge, in this matter, was contrary to the spirit of the rules of Inga. The decision of the judge was appealed, which ultimately led to the adoption of the “Inga Simplified Rules” system, which more strictly regulate the process of completing the game.

The beginning of the game is also associated with certain discrepancies in the rules. When playing "on equal terms", this is Komi - compensation in glasses with white for the first move performed by black. Currently, various values ​​of this parameter are used from 5.5 to 7.5. There is a tendency to increase this value when playing professionals. The fractional value of the Komi is intended to make the draws of the parties impossible (in fact, unlikely, since recognition may be a draw by the judge’s decision).

When playing opponents of different levels, the handicap comes to the fore. A weaker player definitely goes first. If this is not enough to compensate for the difference in level, two approaches are possible. First, a negative Komi value can be used (in favor of a weaker player). The second way is to put the Ura stones on the board, before the start of the game. According to the rules of Inga, the location of the single stones on the board is not regulated. At the beginning of the game, White just skips a few moves, allowing Black to go to any free space on the board. Ing believes that this contributes to greater tactical diversity in the game. In traditional Japanese and Chinese versions of the rules, handicap stones are put on the board in a strictly defined order.

When playing by the Japanese rules, the handicaps themselves do not bring extra points. When scoring according to the Chinese rules, the situation is different. The Chinese and rules based on it compensate for the white glasses associated with the shaped stones. Although according to the rules of Inga, as well as in the Chinese version, the area (and not the territory) is taken into account, compensation is not made for the stones.

It is difficult to say which of the options for the Go game is better. Each of them has both its advantages and disadvantages. In most cases, the result of the game, regardless of the rule system used, will be the same. The rules differ in the nuances, sometimes very subtle, but sometimes these differences become significant (especially when playing professional players). Here you can find a wonderful summary table on various rule options. Perhaps someone it will be useful.