Abstract
Nurse Scheduling Problem (NSP) is a kind of the optimal combination problem. The creation by hand is difficult and the needs for automation are high. Cooperative GA (CGA) is proposed as a solution method effective until now. However, various children are hard to be generated in order that CGA may cross by one parent pair. In this paper, we propose improvement in search efficiency method of CGA. The proposal method generates various children, by crossing by two or more parent pairs, and aims at improvement in search efficiency.