Double ko

Double ko is a Go position in which two ko fights are active simultaneously. Each ko normally requires a player to make a threat elsewhere before recapturing. When two kos are available, one ko can sometimes serve as the source of a threat for the other, so the result depends heavily on the threats available and on the order of play.

Recognizing a double ko is essential when evaluating ko threats, move order, and the potential value of continuing either fight. Unlike a single ko, it contains two simultaneous ko fights. It is distinct from a multi-stage or triple ko, which refers to other repeating-ko structures. The practical result still depends on the exact shape, external ko threats, and the repetition rule in use; two nearby kos do not necessarily have the same strategic value.