令A(yù)={a,b},B={1,2,3},C={p,q}。求出:
(1)A×B×C
(2)B×A
令A(yù)={1,2,3,4 },下列關(guān)系是否是自反的、反自反的、對(duì)稱(chēng)的、反對(duì)稱(chēng)的、傳遞的?
(1)R={(1,1),(1,2),(2,1),(2,2),(3,3),(3,4),(4,3),(4,4)}
(2)Φ
(3)R={(1,2),(1,3),(3,1),(1,1),(3,3),(3,2),(1,4),(4,2),(3,4)}
(1)自反、對(duì)稱(chēng)、傳遞
(2)反自反、對(duì)稱(chēng)、不對(duì)稱(chēng)、反對(duì)稱(chēng)、傳遞
(3)傳遞