Mirror go
Encyclopedia
Mirror go is a type of elementary Go opening strategy. It refers to all go openings in which one player plays moves that are diagonally opposite those of this opponent, making positions that have a rotational symmetry
through 180° about the central 10-10 point (tengen
in Japanese). The Japanese term for mirror go is manego.
There are actually two types of strategy of this kind, and several ways the symmetry can or should be broken for tactical or strategic reasons.
In itself, mirror go is a deeply flawed strategy. It may be refuted in a number of ways: using ladder tactics, using ko fight
s, or most convincingly for a novice by using contact play
s to demonstrate that possession of the central point can just as well lead to shortage of liberties. This has not prevented the circulation of folklore stories about mirror go as some kind of sure-win strategy, eagerly taken up by novice players. Hikaru No Go
episode 8 featured a naive attempt to trick Akira Toya using mirror go, which Toya easily rebuffed using the contact play strategy.
Mirror go can be refuted in boards of odd size rather more easily than those of even size. This is a probable explanation of why odd sizes are always used. (On even-sized boards ladders and kos still can be used.)
After sporadic use down the years, mirror go was brought back into some fashion by the shinfuseki
period, in which the tengen opening
was explored. Subsequently Fujisawa Kuranosuke used it often as White, aiming for large-scale battles.
Rotational symmetry
Generally speaking, an object with rotational symmetry is an object that looks the same after a certain amount of rotation. An object may have more than one rotational symmetry; for instance, if reflections or turning it over are not counted, the triskelion appearing on the Isle of Man's flag has...
through 180° about the central 10-10 point (tengen
Tengen (Go)
Tengen is the name of a Go competition in Japan.The name Tengen refers to the center point on a Go board.The event is held annually, and has run continuously since its inauguration in 1975....
in Japanese). The Japanese term for mirror go is manego.
There are actually two types of strategy of this kind, and several ways the symmetry can or should be broken for tactical or strategic reasons.
- In games without komidashiKomidashiin the game of Go are points added to the score of the player with the white stones as compensation for playing second. Black's first move advantage is generally considered to equal somewhere between 5 and 7 points by the end of the game. Standard komi is 6.5 points under the Japanese and Korean...
compensation points given, Black starts at 10-10 and imitates White subsequently. Black hopes that the possession of the central point will give an edge in an otherwise symmetrical position. - In games with komidashi, White imitates Black from the start. Black can eventually occupy the central point, but White will then hope to show that the game can be made close enough on the board so that the compensation points give a win.
In itself, mirror go is a deeply flawed strategy. It may be refuted in a number of ways: using ladder tactics, using ko fight
Ko fight
A fight is a tactical and strategic phase that can arise in the game of go.-Ko threats and ko fights:The existence of ko fights is implied by the rule of ko, a special rule of the game that prevents immediate repetition of position, by a short 'loop' in which a single stone is captured, and...
s, or most convincingly for a novice by using contact play
Contact play
The contact play is a base running play in the sport of baseball. It can take place with a runner on third base and/or a runner at second base. Similar to the safety-squeeze play, the runner at third breaks for home as soon as he sees that the batted ball is on a downward plane for a ground ball...
s to demonstrate that possession of the central point can just as well lead to shortage of liberties. This has not prevented the circulation of folklore stories about mirror go as some kind of sure-win strategy, eagerly taken up by novice players. Hikaru No Go
Hikaru no Go
is a manga series, a coming of age story based on the board game Go written by Yumi Hotta and illustrated by Takeshi Obata with an anime adaptation. The production of the series' Go games was supervised by Go professional Yukari Umezawa...
episode 8 featured a naive attempt to trick Akira Toya using mirror go, which Toya easily rebuffed using the contact play strategy.
Mirror go can be refuted in boards of odd size rather more easily than those of even size. This is a probable explanation of why odd sizes are always used. (On even-sized boards ladders and kos still can be used.)
After sporadic use down the years, mirror go was brought back into some fashion by the shinfuseki
Shinfuseki
or new opening strategy was the change of attitude to go opening theory that set in strongly in Japan in 1933. It corresponds, a little later, to hypermodern play in chess, with the inversion that shinfuseki thought the center of the board had been unjustly underemphasised.In the 1930s, a group of...
period, in which the tengen opening
Tengen (Go)
Tengen is the name of a Go competition in Japan.The name Tengen refers to the center point on a Go board.The event is held annually, and has run continuously since its inauguration in 1975....
was explored. Subsequently Fujisawa Kuranosuke used it often as White, aiming for large-scale battles.