Empty triangle

In the game of Go, the empty triangle is the most fundamental example of the concept of bad shape.

Empty triangle shape

8 liberties in a 3-stone string X takes up two liberties, leaving 7 Connecting at "a" or "b" is inefficient.

Three stones of one color form an empty triangle when they are placed in a triangle arrangement that fits in a 2×2 square, and when one intersection is left empty.[1] If the triangle is filled by a stone of the opponent's at the fourth point of the 2×2, the shape is neutral – not necessarily good or bad.

The deficiencies of the empty triangle are twofold. Three stones in a straight line have eight liberties, while in an empty triangle they have only seven. This can mean the difference between success and failure in a life-and-death struggle. Also the formation lacks efficiency.[2] In the case cited, the diagonally adjacent stones are tactically connected without the third stone, since the opponent can't prevent them from connecting unless he is ignored for a turn.

However even though the empty triangle is a prime example of bad shape, creating one could make sense, or even qualify as brilliant, in certain situations.[3] An example of this is the third "ghost move" in the famous blood-vomiting game. The move was played by Hon'inbō Jōwa as white against Akaboshi Intetsu. The move allowed Jowa to launch a splitting attack that would ultimately lead to his victory.

The Empty Triangle is also the name of a popular series of comic panels about the game of Go that features personalities from the KGS Go Server.[4]