Partitions of a set n pirates k boats P=[A1,A2,...,Ak}is a partition of S: A,卡0 A∩A)=0 A1UA2U·UAk=SPartitions of a set n pirates k boats P = {A1, A2,...,Ak} is a partition of S: Ai ￾= ￾ Ai ￾ Aj = ￾ A1 ￾ A2 ￾ ··· ￾ Ak = S