Black and White stones are alternately entered onto the intersections of the field of play one at a time with the aim of occupying and surrounding as much area on the board as possible; the pieces are not moved except to be removed from play if they become entirely surrounded. Each intersection occupied or surrounded by a single colour counts as one point for that player at the end of the game. There is also a linear handicapping system that permits players of great skill differences to play on a relatively even footing. According to modern convention, Black must compensate White 6.5 points in even games to negate the first move advantage and eliminate tied results. [Move your mouse pointer over this regulation sized board to see the first ten moves of a game between professional Masters: Kobayashi-Satoru, 9-Dan, and Takemiya-Masaki, 9-Dan]
- Ko & Passing
- Seki & Conditional Life
The "Ko" Rule & Passing:
In GO this is known as the 'Rule of Ko'—the word 'ko' meaning 'eternity' in Japanese—which was instituted to prevent essentially insignificant capture and recapture cycles, like those illustrated in the animation at right.
|Ko creation and alternatives|
|Figure A: Black might execute a 'Ko capture' in each of the 3 examples, by playing at 1; the resulting temporarily banned point in each case is marked (red squares). Mouse-over to view.||Figure B1: Since s/he cannot re-capture immediately at a banned point created by Black 1, White plays 2 with the aim of distracting Black (a "Ko Threat") from occupying the currently banned point on the following turn, since White 2 releases the ban created by Black 1. Black responds to White's threat (of taking a two-move advantage away from the "Ko fight"), with 3, enabling White to create a reciprocal Ko on the following turn, as in Figure C.||Figure B2: Opponent's "Ko Threat" is ignored and the previously banned point is filled, ending the potential for successive Ko situations in this area.|
|progressive Ko sequence and closure|
|Figure C: White 4 recaptures at the previously banned point, creating another temporarily Ko-banned point (red square).||Figure D: Because of the Ko-ban created by White 4, Black plays away, at 5, releasing the Ko-ban, and hoping that White will feel compelled respond to this move so that Black may recapture, recreating the previous (reciprocal) Ko situation, as in Figure A; but...||Figure E: White ignores Black's "Ko Threat", at 5, and fills the previously banned point with 6, ending the "Ko Fight".|
Now you know how to play GO! Try it out a few times on a 9×9 line board with a friend, until you're both used to how capturing works; then, move up toward a regulation 19×19 line size! You won't regret it! If you have questions, or you'd like some help, don't be shy, contact GO for All—that's what we're here for! Beginners are always welcome.
Despite the fact that the side enclosing and occupying more intersections on the board is the winner, Scoring is possibly more complicated than playing the game itself. Nonetheless, the procedure to determine the precise Margin of Victory is quite straight-forward. However, there are two fundamental methods of counting the score at the end of a game of GO—each is equally valid, and both almost universally arrive at the same result. These methods are known as 'Territory Counting' and 'Area Counting'.
Seki & Conditional Life:
- There is a special case, known as "Seki" [SAY-key] where two groups of opposing stones, neither having the requisite two 'eyes' (separately enclosed liberties) to qualify for 'unconditional life', independently; but, share 2 or more liberties in common that neither side is eager to take from the other, because the first side to take one of those common liberties is liable to enable one's opponent to capture the first player's own stones: an example of this is in the accompanying Figure, where the circled empty points are the common liberties.
- If either Black or White occupies one of the common liberties, it will put their own stones into atari, and because of this, both groups are considered to be "Conditionally Alive" and are not liable to be removed from the board during the scoring phase as 'dead stones' even though neither group can live independently. The example, here, is the simplest form, but, more complicated configurations can and do exist.
- The points contained within a "Seki" may be counted differently depending upon the ruleset in use; and, typically, Territory counting considers vacant points within a seki to be 'dame' and therefore of no value to either player, while Area counting considers them 'neutral' and divides them equally to both sides, in addition to permitting the stones enclosing those points to be counted normally, for each side, since they remain on the board.
Territory Counting Area Counting Requires tracking captured stones, which are worth 1 point each. Only stones remaining on the board are significant. Only vacant intersections enclosed by a single colour of stones are counted, some may be invalid. All intersections on the board are counted for one side or the other, some may be shared. Requires both sides to count their score to get the result. Only one side needs to be counted to determine the result. Margin of Victory is the difference between each colour's score. Margin of Victory is double the difference between the counted Score and ½ the goban's total intersections. Safely ignoring an invading stone within one's territory increases one's score. Safely playing on points that cannot be surrounded by a single colour increases one's score. More popular in Japan, and Northern Hemisphere. More popular in China, and Southern Hemisphere.
Although the Area method of scoring is perhaps more efficient, Territory scoring seems to be more easily grasped by new players with limited mathematical experience, viz., young children, despite its being less forgiving of play within one's own territory (cancelling points), and hence why it is also generally used for tournaments.
Territory Counting Procedure:
- Following successive passes, both players must agree on which stones are incapable of avoiding capture. If there is a disagreement, play is resumed with the player who passed first having the right to play first.
- With consensus on the Life and Death status of each group determined, the Dead stones are removed and taken as prisoners.
- All the neutral points—those which are not surrounded by either colour—must be identified and filled with spare stones of either colour (so that they may not inadvertantly be counted as Territory).
- Any groups that are Conditionally Alive ("in Seki") are treated as though the empty points within them are Neutral, and they are filled with spare stones.
- Each player then takes his store of captive stones and uses them to cancel his opponent's territory by placing (repatriating) them onto the empty intersections entirely surrounded by their same colour. Any remaining captives are retained and will count one point each for the side that captured them (in the next step).
- Then count all the vacant intersections, entirely surrounded by each colour, 'territory,' and add that to the number of remaining captives, if any, to get each side's Sub-total.
- Compensate for disparities in capability, and arrive at the Total Score for each side:
- For EVEN games: add 6½ points Komi to White?s Subtotal
- For games where the players are between 1- and 2-stone's strength of each other, the weaker player should play Black and may receive 6½ points of 'Reverse' Komi in addition to having the first move advantage.
- For all other HANDICAPPED games: add ½ point Komi to White's Subtotal
- Compare the Total Scores; the side with the greater score is the winner. Subtract the lower score from the higher score to get the Margin of Victory.
The standard rating nomenclature for GO, world-wide, is Japanese in origin. It begins with "30-kyu" [30 K'yew], for complete beginners, and proceeds upwards to "1-kyu", the most senior Intermediate Amateur rating. Advanced Amateur ratings begin at "1-Dan" [1 DAWN], and proceed further upward to "9-Dan". The principal purpose of ratings is to facilitate setting proper Handicaps between players of different skill-levels. Ostensibly, the difference between two players' ratings is the number of stones the weaker player should place on the board, as Black, before the stronger player may place the first White stone, i.e., White's appropriate Handicap. This is to ensure that both parties may enjoy an equivalent challenge from the contest, and thereby a comensurate potential for growth.
In the Amateur ranks, each level represents a degree of playing ability sufficient to overcome Black's first-move-advantage (worth about 13½ points), while playing as White without Komi compensation, in more than two-thirds of such matches against an opponent one rating level lower. For example, a person rated at 9-kyu should be able to play White against a person rated 10-kyu, and win more than twice as often as the Black player despite the lack of Komi. That difference in skill level between local ratings is generally quite accurate; however, in the global GO community, not all 5-kyus or 6-Dans are the same strength—any given 7-Dan living in Japan may only be as strong as a typical 5-Dan living in China, simply because of the scale of the local population with which that player regularly contends. However, with the advent of online GO the standard deviation of ratings world-wide is diminishing. Online, ratings are generally abbreviated as 30k through 1k, and 1d through 9d. A person's online rating will naturally fluctuate downward as a new phase of learning is being assimilated and gradually rise to a new high point where it will plateau for a while until another learning phase begins.
Curiously, Professional Players are ranked (not 'rated') in a parallel system from 1-Dan to 9-Dan, but the strength differences between rankings in the Professional spectrum are only one-third of a stone; but, a 1-Dan Professional is approximately equivalant in strength to a 7-Dan Amateur. Online, it is common to abbreviate professionals' Dan-ratings as 1p through 9p—the 'p' meaning '(Professional)-Dan'. Demotions within the Professional Ranks practically never happen.
When an un-rated player meets a new opponent, it is usual for the game to be played without handicaps, and then either to estimate a handicap for subsequent games, or use a result-method to adjust the handicap incrementally according to the player's performance. If one of the players has a rating, the other player's rating may be (provisionally) set relative to it. All ratings are initially set in a similar manner; however, the accuracy of such ratings are proportional to the number of other people against whom the rated player has demonstrated a similar relative ability. So, it stands to reason, that the more often one plays, and the larger one's circle of similarly rated opponents is, the more likely it is that one's rating will be accurate.
When players with established ratings meet each other for a game, they will typically use the difference between their ratings to set the handicap. Handicaps of between 2 and 9 are generally implemented as the number of Black stones placed on the board before White places his first stone. This constitutes an increasingly significant, although roughly linear, handicap for White to overcome; therefore, the stronger player is meant to take White in handicapped games. Nonetheless, handicaps of greater than 9-stones are highly-irregular in competitive circles, since each additional stone beyond the 9th is exponentially more valuable—even if they are placed equidistantly from each other—simply due to their relative proximity on a Regulation-sized 19×19 goban. Presumably, if larger gobans were used, larger linear handicaps might be possible.
Japanese convention restricts the location of handicap stones to specific configurations, while other rulesets permit Black to place his handicap stones freely (just as if White had merely 'passed' his intervening moves). The Japanese system guarantees a fixed advantage for each handicap-stone while free-placement affords more skillful or knowledgeable players the latitude to optimize their advantage (to an even greater degree than is provided by the Japanese conventions); similarly, weaker players are as likely as not, given their comparative ignorance of the implications, to inadvertantly handicap themselves using free-placement. When a 1-stone handicap is called for, Black's first move is always freely placed, while the disparity in the players' skill levels is balanced using Komi alone.
The most common heuristic for estimating handicaps when one or both players is un-rated is to have them play an Even game and use one-tenth of the Margin of Victory as the handicap for their next game. Thereafter, their specific handicap is adjusted incrementally according to the win-loss record; typically, if either player wins three (3) consecutive games in a 'sweep', the handicap is adjusted up or down by one stone dependent upon whether it is the stronger or weaker player who has scored the sweep, respectively.
Komi is a fixed number of points, typically 6½, added to White's score to compensate for Black's first-move advantage in games between evenly skilled players. For handicapped games, this is usually reduced to just ½ point, so that any tied results will be awarded to White. Nonetheless, it is appropriate to apply negative (-6½ points), so-called "Reverse", Komi to White when a handicap of just 1-full-stone is called for. Additional amounts of Reverse Komi may be used instead of pre-placed stones to handicap games: -13 points per additional 'stone' in rating difference. For example, if a 6-kyu played White against an 8-kyu, Black might fairly ask for -19½ Reverse Komi rather than taking two Handicap Stones.
© 2016 Tyler Reynolds