Tagai-sen

互い先 (tagai-sen) is a Japanese go term describing conditions of play in which neither player takes a handicap. In a series of tagai-sen games the players would alternate in playing the black stones. Usually, after one player achieved a lead of 4 wins over the other, or some other threshold, the handicap shifted to sen-ai-sen. A game which if lost would result in a shift in the handicap is called a kadoban. For more information on professional handicaps in the days before komi go, see Match Handicap System.